Abstract:A lateral annular slit charge was proposed in order to improve cutting effect in hard rock tuunels. Firstly， the blasting effects of the charge were analyzed theoretically. Then， the distributions of blasting strain and blasting crack after the charge blasting were studied through the model experiments. Finally， field tests were implemented to explore the applied efficacy of the charge. Results showed that the lateral annular slit charge could induce an energy accumulation effect at the slit position， which results in the rock mass at the slit position being subjected to stronger blasting loads and thus having stronger crack propagation ability. The lateral annular slit tube could reduce the blasting strain in the non-slit direction and increase the blasting strain in the slit direction. The strain distribution characteristic proves the energy accumulation phenomenon in the slit direction of the lateral annular slit charge. According to the macroscopic crack propagation， the crack propagation ability of lateral annular slit charge in the slit direction has been significantly improved. Compared with conventional column charge cutting blasting technique， the lateral annular slit charge cutting blasting technique could improve drivage efficiency and reduce cost in hard rock tunnels， which verifys that the lateral annular slit charge is preferred in hard rock tunnel cutting blasting.

Abstract:In order to improve the dispersibility and energy output of nano-boron powder， n-B/NC/F₂₆₀₂ core-shell nanofibers were prepared by coaxial electrospinning method. The morphology of the samples prepared with different core solution mass fraction， shell solution mass fraction， working voltage， distance from needle to collector and injection rate were analyzed by scanning electron microscope（SEM）， and the optimum preparation conditions were explored. Scanning electron microscope （SEM）， X-ray photoelectron spectrometer（XPS） and infrared spectrometer （IR） were used to analyze the morphology of the samples prepared under the best preparation conditions. The combustion performance test， thermodynamic simulation and DSC-TG were used to analyze the combustion performance. The results show that the optimum preparation conditions is 15% of the core layer solution， shell solution mass fraction 15%， working voltage 16 kV， distance between needle and collector 12 cm， core flow rate 3.6 mL·h^-1， shell flow rate 6 mL·h^-1. The average diameter of the spinning product was 1.32 μm. The combustion performance test shows that the highest peak of combustion pressure is 0.51 MPa， and the average pressure boost rate is 0.61 MPa·s^-1， showing excellent combustion performance. Thermodynamic simulation showed that the average molecular weight of the product was 29 g·mol^-1， and the combustion was sufficient. DSC-TG showed that the weight gain of boron in n-B/NC/F₂₆₀₂ was 43.43% more than that of the original boron powder， and the peak exothermic temperature of boron in n-B/NC/F₂₆₀₂ was 41 ℃ lower than that of the original boron powder. The coaxial electrospinning method could better optimize the nanostructure of the fibers.

Abstract:Quantitative characterization of its physical structure is crucial for regulating and enhancing the performance of PBX. Utilizing micro-CT， image processing， and statistical analysis， we researched the quantitative acquisition of characteristic parameters for molding granules. We conducted research on image processing and statistical analysis to quantitatively obtain the characteristic parameters of molding granules based on micro-CT. The characteristic parameters of TATB-based molding granules were characterized by this method， and an evaluation of the characterization method was conducted. The results suggest that this method can implement the quantitative characterization of the size， morphology， porosity， density， and packing characteristics of the molding granules. The granule size and sphericity of the TATB-based molding granules approximately follow the exponential Gaussian and Weibull distributions， respectively. The intrinsic density is 1.35 g·cm^-3， with a visible porosity of 2.3%（@spatial resolution 14.3 μm）， and a volume fraction of 0.69. Evaluation experiments demonstrate that the method exhibits good accuracy， stability， and repeatability. The characterization results of granule size are consistent with those of the sieving process， and the relative deviation of the characterization results of main characteristic parameters in different periods is less than 1%. The results of morphology and properties are relatively significantly influenced by the packing state of granules and the spatial resolution of micro-CT.

Abstract:To investigate the influence of SiC mass fraction， SiC particle size， Al particle size， and their interactions on the mechanical properties of PTFE/Al/SiC （PAS） reactive materials， a 2³ factorial design criterion was employed to design and prepare eight different compositions of PTFE/Al/SiC reactive materials， and quasi-static compression tests and split Hopkinson pressure bar （SHPB） experiments were conducted. Significant factors were selected using the t-value ranking method， and their contribution rates and disturbance trends were analyzed. Additionally， response surface methodology was employed to analyze significant interaction effects. The results indicate that a higher SiC mass fraction positively impacts the mechanical properties of PAS materials. With a sudden change of strain rate， SiC particle size exhibits opposite disturbance trends on the material mechanical response. The effect of Al particles on the mechanical response of the PAS material system is limited. Strong interaction effects between factors should not be overlooked. With low strain rate loading， the interaction between SiC mass fraction and SiC particle size is significant. When the SiC mass fraction is high and the particle size is small， the particle dispersion state and interfacial bonding strength can be optimized， thereby improving material mechanical response. With high strain rate loading， PAS materials with a higher SiC mass fraction exhibit higher dynamic mechanical response， and the interaction between SiC particle size and Al particle size is significant. When the particle sizes of SiC and Al are close， the dynamic response of the material can be effectively improved.

Abstract:Energetic materials are of great strategic value in both national defense and civil application. The thermal decomposition characteristics are one of the most important characteristics directly related to the effective application of energetic materials. It is of great significance to clarify the thermal decomposition behavior and mechanism of energetic materials for further improving the thermal decomposition efficiency and inhibiting their unstable decomposition. Three typical energetic materials， cyclotetramethylene tetranitramine （HMX）， hexanitrohexaazaisowurtzitane （CL-20） and 3，4-dinitrofurazanofuroxan （DNTF）， were studied. The basic physical and chemical properties related to the thermal decomposition characteristics were present， and the thermal decomposition behavior and mechanism were summarized， with emphasis on the structural characteristics of materials and the types of additives that influence the thermal decomposition. It is found that the removal of nitro group is the key step in the thermal decomposition， and the metallic materials rich in active sites and organic complexes with abundant active groups tend to interact with nitro groups to accelerate the thermal decomposition process. Inorganic non-metallic materials can also contribute to the decomposition behavior due to the large specific surface area and excellent gas diffusion ability. Three methods， including eutectic， coating and adding desensitizing agent， are widely used to improve the thermal stability of these three energetic materials. Based on the research of the thermal decomposition mechanism， the design and development of thermal decomposition accelerators and inhibitors can be carried out， which will effectively promote the innovative development of thermal application of energetic materials and become the focus of future research on the thermal decomposition characteristics of energetic materials.

Abstract:Photoacoustic signals were induced on slices of black powder and its components， which was radiated by 1064 nm laser pulses with 10 ns duration. The laser pulse energies were adjusted by regulating the number of fused silica plates on the laser path as attenuators. An optical fiber-based Michelson interferometer was utilized to detect the generated acoustic signals. Acoustic wave energy was estimated. A primary model was proposed to estimate the reaction rate of black powder. Detected phase changes were similar to each other， but the dimensions varied with laser pulse energy. Thermal reaction of blackpowder was not significant under laser radiation， but other reaction mechanism existed and enhanced the photoacoustic signal. Relationship between laser pulse energy and integration of absolute value of phase change is approximately linear. Reaction rate of black powder is positively related to laser energy， except for high-energy pulse. The maximum of reaction rate was about 20 mmol·s^-1， which was achieved when laser energy is around 10 mJ.

Abstract:The safety issues of weapons and ammunition are essential that they matter the survivability and effectiveness of weaponry. The complex and harsh enviroments faced by ammunition lead to the high requirment of ammunition safety that the development of safe ammunition is the only way. Ammunition safety mainly depends on inherent safety and safety enhancement technology. Using insensitive explosives is the key way to improve the inherent safety of ammunition， while the enhancement and protection of charge and structure are important means to improve ammunition safety . In order to meet the requirements of high damage power and safety of ammunition， it is necessary to balance and coordinate the prominent contradiction between high energy and insensitivity of explosives from the multi-scale structures， such as molecules， crystals and mixed systems of explosives. Safety enhancement technologies such as charge structures， weak link structurse of projectiles and protection enhancements can effectively control the accidental ignition， reaction violence and evolution ammunition charges， and furthermore improve the safety of ammunition under abnormal environment and accident conditions. Therefore， the design ideas and technicalapproches for safety ammunition systems were proposed， including strengthening the foundation of multi-scale material design and performance control of insensitive explosives， complementing the shortcomings of charge structures， protection enhancement， and accidental ignition and reaction control， and exploring and developing the integrated design of material，- structure- and function .

Abstract:To study the influence of liner offset on the jet forming and armor breaking process of shaped charge， the numerical model verified by pulse radiography and penetration depth tests was used to investigate the evolution of the pressure distribution on the liner surface， molding parameters and penetration depth under different offsets ranging from 0~0.05D_k. The allowable range of liner offset that meets the requirements of good jet performance was obtained. In addition， the variation law of jet shape and lateral velocity under the coupling of liner deflection and deflection was discussed. The results show that the liner offset affects the symmetric distribution of liner surface pressure at 10μs and 12 μs after initiation （middle and late collapse process）， and a negligible effect observed at 10 μs and 12 μs after initiation（early and finally collapse process）. When the liner offset is 0.0125D_k， the jet maintains good collimation and continuity， and the penetration depth decreases by 6.6% compared with the axisymmetric case； When the offset exceeds 0.0125D_k， the jet bends in a bow shape and breaks at severe bending， with the decrease of penetration depth exceeding 10%. When the deflection angle of the liner is -0.015α， and the deflection changes from 0 to -0.0125D_k， the bending direction of jet changes， and the bending degree decreases first and then increases.

Abstract:The matrix explosives in cast explosives are molten when being ignited under thermal stimulation， thus the hot gas released by reaction expands and reacts in liquid explosives in the physical form of bubble clouds. Considering the scale distribution and activated developing mechanism of burning-bubble clouds， a regulation model for the evolution of burning-bubble clouds after ignition of cast explosives is established. This model well reflected the dependence of reaction evolution and final reaction violence on intrinsic burning rate， shell confinement strength， charging structure size， reserved air-gap volume and pressure relief venting area. Furthermore， the flexibility of this model was verified by comparing the calculated results with the experimental data. Results show that with the increase of shell confinement strength and charge size， the self-sustaining enhanced combustion and reaction violence level increase. Moreover， with the combined design of pressure relief structure venting threshold and pressure relief venting area， the reaction violence of the charge is controlled. Under the charging condition in this paper， when the ratio of pressure relief venting area to shell surface area is up to 8.6‰， the charge reaction violence level is controlled as burning. This work provides a theoretical basis for the thermal safety design and reaction violence evaluation of explosives.

Abstract:Ultrafine 2，6-diamino-3，5-dinitropyrazine-1-oxide （LLM-105） possesses high safety performance and low impact initiation threshold， showing promising applications in the initiation sequence. Solid-phase ripening is the main aging behavior of ultrafine LLM-105 during the storage process， which leads to the growth of particle size and performance degradation. Temperature and humidity are important environmental factors that affect solid-phase ripening， but the microscopic mechanism is still unclear. In situ small angle X-ray scattering （SAXS）， Scanning electron microscope （SEM） and in situ Atomic force microscopy （AFM） were used to capture the structural evolution of ultrafine LLM-105 particles under different temperature and humidity environments， and the solid-phase ripening mechanism was analyzed. Ultrafine LLM-105 had obvious solid-phase ripening after 30 days at 120 ℃， and its specific surface area （SSA） decreased by 41.6%. The ripening mechanism was dominated by Ostwald Ripening （OR）， accompanied with Smoluchowski Ripening （SR）. Humidity significantly accelerates the solid-phase ripening of ultrafine LLM-105 by promoting OR. After 30 days at 60 ℃ and 90% relative humidity， SSA decreased by 35.8%.

Abstract:In order to understand the effect of initial free cavity on the violence of confined octogen （HMX）-based PBX-3 in slow cook-off， the weak restricted test setup was designed with initial free cavity volume ratios of 1.0% and 7.4%， respectively， referring to Sandia instrumented thermal ignition（SITI）. The confined HMX-based PBX-3 explosives were heated at the same rate in slow cook-off tests. The temperatures of different locations at the center plane of explosive and shell surface were acquired using small-sized K type thermocouples， the shell velocity after thermal explosion was measured using the heat-resistant probe of photonic-Doppler-velocimeter（PDV）， and the wreckage of test setup was recycled in the slow cook-off chamber. The results show that the confined PBX-3 explosives are ignited in the center region for the same restricted strength and heating process， no matter with the initial free cavity volume. When the initial free cavity volume ratio is 1.0%， the shell surface temperature and the overall temperature of the explosive are higher when thermal explosion occurs， the shell accelerates faster and the maximum velocity is higher after thermal explosion， the wreckage fragments of test setup are smaller， and the reaction violence is higher. It is analyzed when the initial free cavity volume ratio is 1.0%， the stress of explosive is larger before thermal explosion， resulting in more serious damage. When thermal ignition occurs at the center of the explosive， the larger thermal stress causes a higher pressure induced by the gas accumulation， and the burning rate of explosive is higher. The high-temperature gas generated by the combustion is easier to enter the microcracks， resulting in stronger convective burning， faster pressure growth rate and more violent reaction.

Abstract:In order to explore the effect of 3，4-dinitrofurazan （DNTF） on the explosive energy release process of layered composite thermobaric charges， various double-layer composite charges were prepared， with the content of aluminum powder in the outer charge adjusted from 60% to 94%， and the content of DNTF adjusted from 40% to 0. Then， explosion tests were carried out in a closed tank under nitrogen and air environment. Based on the correlation between quasi-static pressure and effective mechanical energy， the released energy of charges at different reaction stages was obtained. Moreover， the afterburning process of aluminum powder from different charges was analyzed according to the evolution of fireball. The results reveal that the dispersed DNTF particles are easy to be ignited and grow rapidly after being shock-dispersed when the mass fractions of DNTF in the outer charge is 40%， which can improve the anaerobic combustion rate of aluminum powder and the aerobic combustion rate of aluminum powder at the edge of the cloud， thus the combined mechanical energy released during detonation and anaerobic combustion is raised 12% than that of the homogeneous charge with same composition. Whereas， when the DNTF in the outer charge is replaced by polytetrafluoroethylene （PTFE） in the same proportion， the combustion rate after dispersal is significantly reduced as well as shock wave overpressure and temperature， and the total mechanical energy released decreased by about 22% than composite charge containing DNTF in its outer layer. Moreover， when the outer charge is all replaced by aluminum powder， intensely aerobic combustion with longer duration will occur in the high-concentration aluminum powder cloud， the total mechanical energy released drops by only 5%， while the combined mechanical energy released by detonation and anaerobic combustion drops by 32%， and the peak shock wave overpressure has a considerable reduction. The above indicates that DNTF in the outer layer of the composite charge plays an important role in enhancing the combustion rate of the aluminum powder cloud and energy release rate in the early explosion stage.

Abstract:In order to obtain the thermal decomposition properties and melting crystallization kinetic parameters of the lowest eutectic mixture of 3-amino-2，4，6-trinitroanisole （ANTA）/N-methyl-2，4，6-trinitroanisole （TNA）， the thermal decomposition properties of the lowest eutectic mixture of ANTA/TNA were studied by differential scanning calorimetry （DSC）， and the thermal decomposition kinetic parameters were calculated. The effects of additives （HMX and RDX） on the melting process and crystallization process of the lowest eutectic mixture of ANTA/TNA were studied by microcalorimetry. The non-isothermal melting and crystallization behaviors of the eutectic mixture were analyzed by Šatava-Šesták method and Avrami method， respectively. Results show that the lowest eutectic mixture has good thermal stability， and the thermal decomposition kinetic parameters are close to that of ANTA and TNA. The melting process of eutectics conforms to the first-order reaction kinetics， and the heating rate has a great influence on the melting kinetic parameters. Additives can reduce the dependence of melting kinetic parameters on the heating rate to a certain extent. The crystallization process of the lowest eutectic mixture gradually shifts to the low temperature region with the increase of cooling rate， and the crystallization rate decreases with the increase of crystallinity. In HMX medium， the crystallization rate is less affected by crystallinity， and the crystallization rate in RDX increases with the increase of crystallinity.

Abstract:In order to study the morphology evolution of 1， 1-diamino-2， 2-dinitroethylene （FOX-7） particles under thermal stimulus and its influence on mechanical properties and mechanical sensitivities， four kinds of FOX-7 particles with typical size and morphology differences were selected. By controlling heating time and temperature， the morphology， mechanical properties and mechanical sensitivities evolutions of FOX-7 particles after heating were studied by scanning electron microscope， compressive stiffness experiment and mechanical sensitivities tests. The results show that the surface cracks of FOX-7 particles appear after heating and returning to room temperature. With the increase of heating temperature or heating time， the surface cracks of large-size particles （>100 μm） grow and break through ， thus the particles crack in layers and exfoliate. While， the surface cracks of small-sized particles （<100 μm） do not grow with the increase of heating temperature or heating time. Kawakita equation was used to fit the compaction curves of FOX-7 particles before and after heating. It is found that the modulus of FOX-7 particles increase after heating， and the increase is even greater for small particle size. Under the condition of larger particle size， FOX-7 has relatively low mechanical sensitivities， and still maintains low mechanical sensitivities after being heated and returning to room temperature. When the particle size is small， the mechanical sensitivities of FOX-7 are relatively high， and after heating and returning to room temperature， the mechanical sensitivities increase significantly， which may be related to the greater increase of modulus.

Abstract:In order to increase the density and detonation energy of the explosive， hydroxyl-terminated fluorine-containing binder （HTFB， 1.40 g·cm^-3） was applied to the formulation of casting PBX explosive （polymer bonded explosive）. The effects of toluene diisocyanate （TDI）， isophorone diisocyanate （IPDI）， hexamethylene diisocyanate （HDI） and hexamethylene diisocyanate trimer （3HDI） on the viscosity and curing process of the binder system were studied， and the effects of curing agents on curing and mechanical properties were also investigated. Results show that the curing agent can significantly reduce the viscosity of the binder system. In the temperature range of 25-70 ℃， the higher the temperature， the lower the viscosity of the binder system was. Above 60 ℃， the viscosity of HTFB binder system changed gently and the difference of each system was small. As curing agent， the viscosity， opening time and gel time of trifunctional isocyanate are more suitable for the preparation process of casting PBX explosive. Based on the formulation of aluminum-containing casting explosive with 88% solid content and the preparation process of pinch-vacuum injection-curing， the influence of HTFB binder on the preparation process and properties of explosive was studied in comparison with HTPB. The HTFB based PBX explosive show decent casting rheological properties and curing quality， and the density and detonation heat are 1.96 g·cm^-3 and 7790 J·g^-1， which are 6.52% and 6.55% higher than that of HTPB based PBX explosive， respectively.

Abstract:Aluminum hydride （AlH₃） is a new energetic material with higher energy density than aluminum. A large amount of hydrogen produced in the combustion of AlH₃， which significantly reduced the average molecular weight of gas products. AlH₃ can be used as an energetic component of explosives. However， the crystal transformation process of AlH₃ is extremely dangerous and the unstable impurity phase is difficult to separate， thus it is challenge to obtain the pure stable phase α-AlH₃. The preparation of AlH₃ complexes can avoid the danger of crystal transformation of AlH₃， AlH₃ complexes retain the structural unit of AlH₃， avoid the dangerous crystal transformation process， and can be purified by recrystallization， which has a broad application prospect. This paper reviews the synthesis methods， coordination modes， types and applications of AlH₃ complexes， and focuses on the effects of different ligands， such as tertiary amine， tertiary phosphine， ether and carbene， and different coordination structures on the thermochemical properties of AlH₃ complexes. The future research direction of AlH₃ complexes is clarified.

Abstract:In order to study the effects of hydrogen storage tantalum powder （HTa） on the material density and energy density of Al/PTFE reaction materials， four different Al/HTa/PTFE cylindrical specimens were prepared with varying HTa contents （5%， 10%， 20%， 30%）， and Al/PTFE cylindrical specimens without HTa were also prepared. A comparative study was conducted through Hopkinson pressure bar experiments and ballistic gun penetrating target experiments to analyze materials" dynamic mechanical properties， ignition thresholds， impact damage， and energy release characteristics. The results indicate that both Al/PTFE and Al/HTa/PTFE are elastoplastic materials with consistent stress-strain behavior. The ignition thresholds of the four Al/HTa/PTFE materials were measured as 4470 s^-1， 5620 s^-1， 5135 s^-1 and 3948 s^-1 respectively， with the ignition delay time decreasing and then increasing with increasing HTa filler content. In comparison with the Al/PTFE reactive materials， the reaction zone of Al/HTa/PTFE projectiles significantly expands between spaced targets， resulting in severe black scorch marks on the target plate and the generation of carbon deposition effect. The penetrating ability and secondary fragment damage were improved， further enhancing the material"s target penetration damage level.

Abstract:Aiming at solving the problems of the structural design and the applicability of the penetration performance of dual-mode warhead， a dual-mode warhead with arc-cone combined shaped liner of variable wall thickness is designed. Using ANSYS / LS-DYNA simulation software， the influence of shaped charge structure parameters on the characteristic parameters of dual-mode damage elements is studied. Based on the optimized structure， the damage of different damage elements to concrete targets is studied. Through the range analysis， the optimal combination of the structural parameter of dual-mode warhead is obtained： the cone angle of the liner is 80°， the arc radius is 8 mm， the upper wall thickness of the liner is 2.22 mm， the lower wall thickness is 5.44 mm， the length-diameter ratio of the charge is 0.88， and the shell thickness is 5 mm. The X-ray imaging test is carried out to verify the optimization results. The results show that the simulation results are in good agreement with the X-ray test results. Compared with the shaped charge jet （JET）， the rod-shaped charge jet （JPC） has obvious advantages in surface collapse and opening performance when penetrating concrete targets， while the penetration depth of JET to concrete targets is significantly improved compared with JPC. The research results can provide reference for the design and application of warhead structure.

Abstract:In order to obtain a new type of alloy fuel with excellent thermal oxidation and energy release performance， the spherical aluminum-tungsten alloy fuel powder （Al-25W） was prepared by the combination of aluminothermic reduction and ultra-high temperature gas atomization. The phase structure， oxidation behavior， and energy properties of the alloy powder were studied. The results show that the metastable Al/W alloy phase in the spherical Al-25W alloy powder particles is uniformly distributed in the pure Al matrix， and transform into the Al₁₂W phase after the stabilization treatment， and the energy is released to the outside. The spherical Al-25W alloy powder has higher oxidation heat release and oxidation weight gain than pure Al powder. It can be completely oxidized in air at 1400 ℃， with all W atoms oxidized to WO₃ and volatilized in the gaseous form. The residual oxidation product is only Al₂O₃. The measured volumetric combustion enthalpy of the spherical Al-25W alloy powder is higher than that of pure Al powder （83000 J·cm^-3） calculated theoretically， up to （83132.1±608.5） J·cm^-3， and the gaseous combustion product WO₃ is generated during the violent combustion.

Abstract:Fluoropolymer-matrix reactive materials are a new type of material with energy release characteristics of impact reaction. It has a wide application prospect in the military field. In order to master the energy release and damage characteristics of fluoropolymer-matrix reactive materials and promote its application in high-efficiency damage warhead， the research status of impact-induced chemical reaction behavior of fluoropolymer-matrix reactive materials and the coupling damage effect of ignition， detonation， invasion and explosion are reviewed. The research progress in energy release characteristics of split Hopkinson pressure bar （SHPB） experiment， quasi-closed ballistic experiment and explosive loading experiment is emphatically introduced. In terms of damage characteristics， the research progress of reactive projectile， fragment and reactive jet is summarized， the application design of fluoropolymer-matrix reactive materials in shaped charge and the research results of reactive jet forming are emphasized. Besides， the related reaction model and numerical simulation are introduced. On this basis， the future research direction is discussed： establishing a systematic response model and simulation method； regulating its performance by formula， process and other parameters； innovating and exploring the observation and characterization technology of energy release reaction and giving engineering application designs.

Abstract:In order to study the burning damage characteristics of polyurea anti-blast layer under the action of explosion transient temperature field， experimental tests were carried out for the polyurea coated capsule liquid-filled container with different thickness （1 mm， 4 mm and 6 mm） under the condition of close-in explosion. The macro-micro damage characteristics of the polyurea layer after explosion transient high temperature burning were obtained by explosion experiment， and the burning mechanism of the explosion temperature field on polyurea was analyzed using the colorimetric temperature technology and the numerical simulation method. The results showed a maximum explosion temperature of passivated hexogen （RDX） of about 3792 K under the described experimental conditions， which was higher than the initial decomposition temperature of the polyurea material （231.2 ℃）. The burning phenomenon occurred on the surface layer of the polyurea. When the thin layer between the surface layer and the internal hole was broken by penetration， the detonation product entered the internal hole of the material， thus resulting in a significant increase in the burning depth of the polyurea and the formation of a spotted burning outer layer. The ignition degree of polyurea was positively correlated with the density of detonation products and the propagation velocity of detonation products along the thickness of the polyurea layer. Besides， ignition occurred when the mass per unit area of detonation products acting on the polyurea layer reached 0.0195 g·cm^-2. Heat conduction was the main reason for the thermal decomposition of polyurea. Overall， the research method and results could provide reference for the engineering protection evaluation of polyurea and the modification of anti-blast polyurea.

Abstract:Limited by the size of model test chamber， the reflection wave generated by explosion load on the boundary of test chamber would inevitably affect the expected results in the centrifugal tests of underwater explosion. Therefore，reducing the boundary effect will substantially restore the actual test situation and improve the test accuracy. Numerical simulation on centrifuge model test of underwater explosion was conducted based on the Coupled-Eulerian-Lagrangian（CEL） method，. Through comparing experimental results with theoretical results and analyzing mesh sizes of 1， 2， 4， 6， 8 and 10 mm， the reliability of the numerical model was verified. Based on that， the shock wave propagation characteristics in centrifuge tests of underwater explosion with boundary energy absorbing materials of rubber and foam （thicknesses of 5， 10， 15 and 20 mm） were compared， and the mechanism of wave absorption and energy dissipation was analyzed. The results show that the Euler mesh size of 2 mm could balance the calculation efficiency and accuracy of calculation results. Laying rubber or foam materials on the inner wall of the model chamber could effectively reduce the reflection effect of underwater explosion shock waves. The rubber material is more effective in shock wave absorption than the foam material for the condition of 5 mm thickness. However， with the increase of material thickness， the foam material has a better absorption effect than rubber. Both rubber and foam materials have a certain inhibitory effect on low-frequency signals of shock waves， but the inhibitory effect on high-frequency signals is weak.

Abstract:To study the jet formation and failure characteristics of penetrating concrete and rock targets of shaped charge with large barrier， the jet formation by using X-ray cinematography and static armor-piercing into concrete and rock targets were carried out. Meanwhile， the evolution process of detonation wave， the rod jet formation of shaped charge with large barrier and penetration process of concrete and rock targets are simulated by ANSYS/AUTODYN software. Combined with the experimental results， the penetration damage characteristics of the shaped charge rod jet to concrete and rock targets were analyzed. Results show that the Lee-Tarver equation of state can accurately describe the propagation process of the internal detonation wave， and the maximum error of forming jet parameters （projectile length， jet length， jet head velocity and jet diameter） is 12.8% compared with the test. The continuous rod-like jet with large aspect ratio can be formed after detonation of the shaped charge with large barrier. There are obvious craters in the penetrated concrete and rock targets， and the jet has no obvious reaming effect during the penetrating concrete process. The penetration depth and hole diameter of the penetrated concrete target are 46.7% and 48.1% larger than those of rock target in the test. However， the surface of the rock target is seriously damaged and the crater area is larger. Compared with the concrete target， cracks in rock target are continuously generated and developed significantly in the process of jet penetrating and the length and width of cracks formed are larger than those of concrete targets. The damage range around the rock target penetration channel is larger， and the internal damage of the target is serious.

Abstract:To select and optimize the formulation components of high-energy Fuel air explosive， petroleum ether， propylene oxide， and ethyl ether （liquid fuel）， isopropyl nitrate and nitromethane （liquid sensitizer）， and metallic aluminum powder （solid component） were used as the research objects. The explosion pressure and explosion temperature of FAE with different composition ratios was investigated by EXPLO5 calculations. The cloudburst experiments of liquid and liquid-solid FAE formulations were also conducted under unconstrained conditions， and the parameters such as explosion field and temperature field were analyzed for the damage effect. The results show that the mixed liquid FAE， composed of petroleum ether （mass accounted for 55%-70%）， propylene oxide， and isopropyl nitrate， shows a better detonation performance.. The liquid-solid mixture of FAE with a liquid-solid ratio of 1∶1 has a better detonation performance and shows the best cloud dispersion state in the unconstrained cloud dispersion experiment. Two systems of FAE formulations in the 1 kg of secondary detonation charge under the cloud burst can be a stable response to achieve the detonation state. They all have superior results in terms of destructive capacity. Also， the effects of heat damage and overpressure damage were quantified and evaluated for each system.

Abstract:By using penetration experiment and numerical simulation methods， the damage characteristics of the multilayer thin steel target penetrated by reactive materials （RMs） under hypervelocity impact condition was investigated. The two-stage light gas-gun was used to study the damage mode of PTFE/Al based RM and Al-based all-metal RM to multilayer thin steel target， the influence of material type and penetration velocity on damage effect is presented. The results show that， compared with inert metal， both of RMs have lateral damage enhancement effect on multilayer thin steel target， which the broken hole size of the second layer can reach more than 4 times of the bullet dimeter （BD）. The AUTODYN numerical simulation software was used to prove the efficiency of the RM parameters and then the damage effect numerical simulation of RMs were carried out. The results show that the damage characteristics of PTFE/Al-based RM and Al-based all-metal RM to multilayer thin steel target can be described by J-C model combined with Lee-Tarver model and J-C model combined with Shock equation respectively. Additionally， the phenomenon that the increase in penetration speed can hardly improve the lateral damage enhancement effect of the PTFE/Al-based RM but can significantly improve that of the Al-based RM to the multilayer steel target， which is mainly due to the difference in energy releasing mechanisms between two kinds of RMs.

Abstract:In order to investigate the shock initiation of warhead charge by multiple explosively formed projectiles （MEFP） impacts， the shock initiation experiments of covered Composition B by single EFP and dual EFP were conducted to test the shock initiation capacity of single EFP and dual EFP on covered Composition B. Moreover， the numerical simulations on shock initiation of covered Composition B by EFP were carried out by AUTODYN finite-element software， the formation processes of single EFP and dual EFP and their shock initiation processes of covered Composition B， were analyzed respectively， and the critical cover plate thickness （H_c） for the detonation of Composition B was obtained. Further， an engineering calculation model of the critical initiation condition of covered charge with dual EFP was established. The experimental results show that the length of EFP is 18 mm and the diameter is 19 mm. The critical cover plate thickness range is 10 mm≤H_c<15 mm for shock initiation of covered Composition B by single EFP impact， while the critical initiation cover plate thickness range is 15 mm≤H_c<20 mm for dual EFP impacts. Besides， the numerical simulation results show that the critical cover plate thickness is 13 mm for shock initiation of covered composition B by single EFP. While for the action of double EFP， the critical initiation cover plate thickness is 19 mm， which is 46.2% higher than that for single EFP. The numerical simulation results are consistent with experimental results. Finally， the calculation model can provide a good prediction of the critical initiation condition of the covered charge with dual EFP.

Abstract:The cylinder test is one of the most commonly used tests to calibrate the parameters of the equation of state for explosive detonation products. A probe cylinder test platform was designed and established in order to determine the parameters of the JWL equation of state for explosive detonation products. A 20 ns high-resolution pulse chronograph and a set of probes with radial displacement differences were used to record multiple discrete points during the expansion process of the cylinder. When the cylinder expands to the head of the probe to form a circuit loop， the pulse chronometer records the time. Based on this， the displacement-time history curve of the cylinder wall can be obtained. Two probe cylinder tests of TNT explosives were carried out， and discrete points of cylinder expansion displacement were obtained. The experimental results show that the difference between the two sets of test curves is small， indicating that the probe cylinder test has good repeatability. The JWL equation of state parameters of TNT explosive detonation products were determined using the BP-GA algorithm. The determined JWL parameters were then substituted into the finite element software for numerical verification， and the results showed that the determination coefficient R² of the simulation displacement curve was 0.9997， indicating the high accuracy of JWL parameters.

Abstract:In order to evaluate the effect of damp-heat aging on the properties of pentaerythritol acrolein resin （123 resin）-RDX polymer， experimental study on accelerated aging by dampness and heat was carried out. The moisture absorption properties of pouring PBX explosive specimens， mechanical properties before and after moist heat aging， section morphology and aging mechanism were analyzed by means of water adsorption instrument， material testing machine， scanning electron microscope and infrared spectrum. The results showed that the moisture absorption rate of RDX， 123 resins and pouring PBX increases with the increase of relative humidity. Among them 123 resins has the highest moisture absorption rate. Relative to the main explosive RDX has stronger hygroscopic property. The results show that the moisture absorption of pouring PBX is dominated by 123 resins in the system. The results of infrared spectrum showed that 123 resins had hygroscopic hydrolysis after heat and hunmidity aging， Meanwhile， moisture and heat aging significantly affected the mechanical properties of 123 resins-based casting PBX. The mechanical properties of 123 resin based cast PBX decreased significantly with the increase of ambient humidity， and the mechanical properties decreased obviously with the extension of aging time.. After aging at 65 ℃/90% RH for 5 days， the compressive strength decreased by 17.60 MPa（24.09%）， the tensile strength decreased by 2.32 MPa（28.78%）， when aging for 30 days， the compressive strength decreased by 77.80% and the tensile strength decreased by 58.56%； The results showed that 123 resins based casting PBX was sensitive to humidity， and the hydroscopic hydrolysis of 123 resins was the main reason for the significant decrease of the mechanical properties of casting PBX.

Abstract:Microbial remediation technology refers to the remediation technology that uses artificially domesticated microorganisms with specific functions to degrade harmful pollutants in the contaminated site into harmless substances through their own metabolism in the appropriate environment. In the process of microbial remediation of energetic compounds contaminated sites， improving microbial degradation efficiency and exploring metabolic pathways and intermediate metabolites are key issues. This paper briefly described the pollution status of energetic compounds， introduces common methods for remediation of energetic compounds contaminated sites. The advantages of microbial remediation of energetic compound contaminated sites were focused on， and the common strains， external nutrition sources and practical applications of microbial remediation of energetic compound contaminated sites were summarized. Besides， the intermediate metabolites produced by various energetic compounds in the process of microbial degradation were sorted out， and the metabolic pathways in the degradation process of various energetic compounds were also summarized. The development trend of microorganism application in remediation of energetic compound contaminated sites was prospected. The prerequisite for improving the efficiency of existing microorganisms in degrading energetic compounds is the research of microbial agents with better biological stimulation effect. The analysis of metagenomics， macronenenebb transcriptome， macronenenebc proteomics and metabolomics of microbial strains that degrade energetic compounds should be emphasized as a way to strengthen the research on DNA， RNA， proteins and metabolites， and also to improve the degradation effect through transgene to better stimulate the potential of microbial remediation of energetic compound contaminated sites.

Abstract:The typical energetic compounds represented by 2，4，6-trinitrotoluene （TNT） have multiple toxic effects， which seriously threaten the life and health of of production personnel. In order to comprehensively understand the toxic effects of various typical energetic compounds， TNT， cyclotrimethylene trinitramine （RDX）， cyclotetramethylene tetranitramine （HMX）， hexanitrohexaazaisowoodane （CL-20）， 1，1-diamino-2，2-dinitroethylene （FOX-7）， 2，4-dinitroanisole （DNAN）， 3-nitro-1，2，4-triazol-5-one （NTO）， 1，1''-dihydroxy-5，5''-bitetrazole dihydroxylamine salt （HATO） and ammonium dinitamide （ADN） 9 common typical energy compounds in mammals， and their main toxic effects were reviewed. It was pointed out that TNT has genotoxicity， carcinogenicity， reproductive toxicity and other toxic effects， which can lead to anemia， lens abnormalities， cataracts and other toxic diseases. CL-20 with genetic toxicity， can induce deoxyribonucleic acid （DNA） oxidative damage and mutation. RDX and HMX are neurotoxic substances and can induce neurotoxic symptoms such as epilepsy. NTO， ADN and FOX-7 have strong reproductive toxicity and can damage the male reproductive system. DNAN and HATO have immune system toxicity， can interfere withlymphocyte levels and damage the spleen. At the same time， it is suggested that the toxic mechanism of energetic compounds should be further studied in the future. Strengthen the research of toxic protection technology of energetic compounds， explore the toxic effect of new energetic compounds and the combined toxic effect of multi-energetic compounds.

Abstract:In order to overcome the problems of easy agglomeration， easy oxidation and poor combustion performance of nano-boron powder， fiuorine rubber（F₂₆₀₂） was used as binder.Nano-boron/F₂₆₀₂ composite microspheres with different process parameterswere prepared by electrostatic spray method.The perparationtechnology of composite microspheres were optimized by orthogonal experiment， and the best preparation conditions for uniform particle size and rounded morphology of microspheres were been found. The morphology， structure and thermal properties of the composite microspheres were characterized by scanning electron microscopy， X-ray diffraction， infrared spectroscopy， and thermogravimetry. The results show that the optimum preparation conditions were as follows： solution concentration 7%， the content of F₂₆₀₂ to boron power 3.5%， the injection rate 1 mL·h^-1 and the injection voltage 18 kV. The prepared nano-boron /F₂₆₀₂ composite microspheres have good dispersion， and the serious agglomeration of nano-boron powder is improved. The boric acid peak on the surface of boron nanoparticles did not appear on the composite microspheres， indicating that the composite microspheres prepared by electrostatic spraying can effectively prevent the surface oxidation of boron nanoparticles. Compared with the raw boron powder， the weight gain of the composite microspheres increased by 22.98%， and the reaction degree with oxygen was deeper， and the boron energy release was more complete.

Abstract:In order to enhance the compatibility of α-AlH₃ with HMX and CL-20， silane coupling agents with different organic functional groups were used to coat α-AlH₃. The structure and morphology of α-AlH₃ were characterized by X-ray diffractometry （XRD）， infrared spectroscopy （FT-IR）， X-ray photoelectron spectroscopy （XPS） and scanning electron microscopy （SEM）， and the compatibility of α-AlH₃ and modified materials with HMX and CL-20 were investigated， respectively. The results showed that the silane coupling agent could form a uniform cladding layer on the surface of α-AlH₃ without changing its native structure. γ-thiopropyl triethoxysilane （KH580） coating improves the thermal stability of α-AlH₃， increases the maximum thermal decomposition temperature by 1.7 ℃ and increases the activation energy E_a value by 2.21 kJ·mol^-1. After the modification of KH550 and KH570 ， the compatibility of α-AlH₃ and HMX hybrid system increased from level 3 to level 1. After the modification of KH550， the compatibility of α-AlH₃ and CL-20 mixed system is increased from level 4 to level 1.

Abstract:Quickly and accurately detect and analyze the intermediates and impurities produced in the synthesis of Hexanitrohexaazaisowurtzitane （CL-20）， is important for controlling the purity or quality of CL-20， and ensuring its sensitivity and detonation performance. In this study， nuclear magnetic resonance （NMR） and ultra-high performance liquid chromatography-Quadrupole time-of-flight mass spectrometry （UHPLC-QTOF-MS） were used to rapidly and efficiently analyze the impurities in the typical synthesis process of CL-20. The results showed that the impurity in HBIW was 1，3-dibenzyl imidazole， the impurity in tetraacetyl dibenzyl hexazepane （TADB） was low acylated triacetyl tribenzyl hexazepane （TATB）， and the impurity in tetraacetyl hexazepane （TAIW） was incomplete TADB. The impurities in CL-20 were not fully nitrated monoacetyl pentanitrohexazazine （MPIW） and diacetyl tetranitrohexazazine （DATN）.

Abstract:To explore the explosion characteristics of propylene oxide mist， a 20 L spherical liquid fuel explosion test system was used to study the effects of ignition delay time and mass concentration on the explosion characteristics of propylene oxide/air mixture. At the same time， high-speed cameras were used to photograph the flame propagation process， the dynamic distribution images of flame temperature field was reconstructed by colorimetric pyrometer technology and the effect of mass concentration of propylene oxide on the flame temperature was discussed. The experimental results showed that with the increase of ignition delay time， the maximum explosion overpressure and the rise rate of maximum overpressure increased first and then decreased， while the combustion duration was on the contrary. The optimal ignition delay time was 100 ms with the maximum explosion overpressure reached 0.89 MPa. With the increase of the mass concentration of propylene oxide，the maximum explosion overpressure， maximum overpressure rise rate and maximum average flame temperature were all initially increased and then decreased. When the mass concentration was 498 g·m^-3， the maximum explosion overpressure and maximum overpressure rise rate were both the highest， which were 1.02 MPa and 60.91 MPa·s^-1， respectively. But the mass concentration corresponding to maximum average flame temperature was significantly lower than that of maximum explosion overpressure. When the mass concentration was 415 g·m^-3， the flame average temperature reached the maximum value of 1937 K. The research results can provide reference for optimization of detonation performance and evaluation of damage efficiency of the fuel air explosive.

Abstract:In order to treat the acidic washing water in the industrial production， heterogeneous photo-fenton degradation-blowing off is proposed. Firstly， the magnetic catalyst Fe²⁺-Fe₃O₄@AC was prepared by coprecipitation-impregnation. Then，the degradation of NTO in the washing water （about 4 g·L^-1） with system （UV/Fe²⁺-Fe₃O₄@AC/H₂O₂） was studied. pH， addition of H₂O₂ and catalyst concentration were screened to obtain the best conditions. Five repeated experiments were carried out to study the catalyst stability. The importance of conditions， free radical quenching experiment and the EPR spectrum results were studied to speculate on a possible degradation mechanism. In the process of degradation under optimal conditions and blowing off， the change of COD and NH₃-N were recorded.The results show that this system can degrade NTO efficiently. When pH is 2， n_H2O2∶n_NTO is 5 and catalyst concentration is 1 g·L^-1， 99% of NTO can be removed in 150 min. The catalyst has good stability and the NTO removal rate can still reach 82% after 5 cycles. The removal rate of COD and NH₃-N are both 99% after degradation and blowing-off.·OH and ·O₂^- make a contribution to degradation and ·OH plays a major role.

Abstract:To investigate the temperature effects on fracture behavior of HMX-based polymer bonded explosives （PBX） under quasi-static loading， the digital image correlation method （DICM） and crack propagation gauge （CPG） testing system were used in quasi-static fracture tests of the semi-circular bending （SCB）. The fracture characteristics， fracture resistance， damage tolerance and crack unstable propagation rate of HMX-based PBX at different temperatures （25 to 65 ℃） were studied. The results show that with the increase of temperature， the fracture characteristics of HMX-based PBX gradually transform from brittle fracture to ductile fracture， the fracture toughness which indicates the crack initiation resistance significantly decreases， and the damage tolerance is slightly improved. Under the brittle fracture condition of SCB， the crack unstable propagation rate shows a slow-fast-slow law on the propagation path， with a maximum rate of about 370 m·s^-1. The increase in temperature leads to some reduction in the crack unstable propagation rate.

Abstract:In order to study the relationship between impact sensitivity （IS） and molecular structure of nitrogen-rich energetic ionic salts，the configuration optimization and quantum chemical parameter calculation of 21 kinds of energetic ionic salts were carried out at the M06-2X/6-311++G（3df，3pd） level， in which the energy of the highest occupied molecular orbital （E_HOMO）， the energy of the lowest unoccupied molecular orbital （E_LUMO）， the total dipole moment （μ）， the polarizability （α）， the oxygen balance （OB）， the Nuclear Independent Chemical Shift （NICS）， the available free space （ΔV）， the variance of electrostatic potential value on the van der Waals molecular surface （σ²）， the ionization potential （I） and the electron affinity （A） were used as descriptors. The quantitative structure-property relationship study （QSPR） between these descriptors and IS， with the correlation coefficient and root-mean-square error were 0.98 and 0.11， respectively， was built by principal component analysis （PCA） combined with support vector machine （SVM）. The QSPR was used to predict the IS of six newly designed nitrogen-rich energetic ion salts. It is found that the impact sensitivity of the three energetic ion salts （17-35 J） designed based on bis-heterocycle-substituted 1，2，3-triazole （HTANFT） is higher than that of the traditional explosive TNT （15 J）， which indicates that the three energetic ion salts designed based on HTANFT are potential ideal insensitive energetic materials.

Abstract:To figure out the coating mechanism of polymer bonded explosives （PBXs） prepared by spray drying and the effects of binders types and contents on the performance of PBXs， refined 1，1-diamino-2，2-dinitroethylene （FOX-7） and FOX-7 based PBXs with different binder types and contents were prepared by spray drying at the presence of poly ester urethane elastomer （Estane 5703）， fluororesin （F₂₃₁₄）， fluorine rubber （F₂₆₀₂） and acrylic rubber （ACM） as binders， respectively. The surface morphology， crystalline states ， thermal decomposition properties and impact sensitivity of the samples were characterized by field emission scanning electron microscopy （FE-SEM）， X-ray diffractometer （XRD）， differential scanning calorimeter （DSC） and impact sensitivity instrument， respectively. The results indicated that the crystalline state of the resulting samples was α-type. The FOX-7 based PBXs composited by Estane 5703 had the best sphericity， surface smoothness and mechanical safety， while the apparent activation energy decreased by 10.61%. The PBXs composited by F₂₆₀₂ exhibits satisfactory thermal stability. Both binders can effectively reduce the impact sensitivity of FOX-7. When the compounded binders containing Estane 5703 and F₂₆₀₂ at the mass ratio of 4∶1 content was 3%-5%， the surface of FOX-7-based PBXs particles is smooth and the adhesive effect is attractive. When the compounded binder content was 5%， the resulting FOX-7-based PBXs possess excellent safety performance. The compositing structure and desensitization mechanism of binders in PBXs obtained by spray drying were analyzed from the microscopic morphology of FOX-7 in molten state. And the comparative analysis of impact sensitivity， atomic ratio of surface elements and chemical state changes between refined FOX-7 and resulting PBXs was carried out to verify them.

Abstract:In order to explore the effect of biodiesel on the thermal decomposition characteristics and vibration resistance of on-site mixed emulsion explosives， the microscopic structure， thermal decomposition characteristics and vibration resistance of the matrix samples of on-site mixed emulsion explosives with biodiesel as the oil phase material were studied by laser particle size analyzer， optical microscope， synchronous thermal analysis technology， vibration experiment and water dissolution method， in which the mass contents of biodiesel were 0%， 1%， 2% and 3%， respectively. The results show that the average particle size of the on-site mixed emulsion explosive matrix samples with biodiesel is smaller， the uniformity of the internal phase particles is better， and the average particle size and dispersion index are reduced by 12.9% and 38.0% respectively， compared with the sample without biodiesel. When the mass content of biodiesel in the sample is 3%， the initial temperature， peak temperature and activation energy of the decomposition reaction are reduced by 5.8%， 3.7% and 12.3%， respectively， compared with the in-situ mixed emulsion explosive matrix sample without biodiesel， indicating that the thermal stability is reduced. The anti-vibration performance of the on-site mixed emulsion explosive matrix sample with 3% biodiesel is the worst. The dissolution loss rate increases from 0.117% to 0.313% after 6 vibration periods， and the crystallization phenomenon appears after 4 vibration periods. The on-site mixed emulsion explosive matrix sample with 1% biodiesel has the best anti-vibration performance. After 6 vibration periods， the dissolution rate increases from 0.070% to 0.197%， and no crystallization occurs. When the content of biodiese is 1%， the average particle size of the internal phase is small， the distribution uniformity is good， the thermal safety is high and the vibration resistance is the best.

Abstract:To study the fuel dispersion and detonation process at a falling speed of 1000 m·s^-1， a computational simulation model of fuel dispersion detonation was established， and the static fuel dispersion and cloud detonation experimental results were used as numerical methods to verify the results. Results show that under the condition of a falling speed of 1000 m·s^-1， the distribution of cloud shape and concentration field with time and space is obtained by numerical simulation. The cloud shape is roughly fan-shaped， and the concentration gradually decreases with distance， and finally reaches a stable distribution. The radial radius of the cloud can reach 2.24 m. The law of the cloud detonation process and the influence of the detonation pressure field and temperature field are obtained. After initiation， the arc-shaped wave front is formed and diffuses outward， and the temperature and pressure continue to decay. The numerical simulation results are consistent with the experiments， which provide a new way for the safety design of the high-falling velocity cloud explosion weapon system.

Abstract:A new shock initiation measuring system is developed with the reverse-impact method， in which the explosive sample was driven by a gas gun and impacted the LiF window at a certain speed. The photonic Doppler velocimetry （PDV） was used to measure the interfacial particle velocity profile between the explosive sample and the LiF window. This measuring system has higher accuracy （3%）， higher time resolution （5 ns） and lower requirement of explosive samples than previous shock initiation measuring methods. Moreover， to explore the effect of aluminum powder， the shock initiation characteristics of three RDX-based aluminized explosives （RDX/Al） with different contents of aluminum powder （0， 15% and 30%） were investigated by this measuring system. The experimental data indicates that with the same impacting speed， the shock initiation reaction growth becomes slower with a higher content of aluminum powder. The interfacial particle velocity of the RDX-based aluminized explosive with 30% aluminum powder requires more time to arrive at a peak value， which is 47% longer than that of the RDX explosive. The aluminum powder makes the shock sensitivity significantly decrease and it plays a dilute role in explosive energy during the shock initiation process of aluminized explosives.

Abstract:To investigate the effect of doping La₂O₃ on the reactive characteristics of Al/CuO thermite， Al/CuO thermites with equivalent ratio（φ） of 1.0， 1.4 and 1.8 doped with different content of La₂O₃ were prepared by mechanical mixing method. The samples were characterized by scanning electron microscope（SEM）， X-energy dispersive spectrometer（EDS）， X-ray diffractometer（XRD） and differential scanning calorimetry（DSC）， respectively. Combustion and gas production performances were evaluated by using flame propagation experiment， T-jump ignition and pressure cell test. The results show that the initiation reaction temperature and the peak temperature for the Al/CuO thermite doped with La₂O₃ were significantly lower than those of Al/CuO thermite without doping La₂O₃ at φ=1.4. The heat release of Al/CuO thermite was 1772 J·g^-1 when 2% La₂O₃ was doped， which increased by 15.1% compared with that of the undoped Al/CuO thermite （~1540 J·g^-1）. The combustion rate of Al/CuO thermite with 2% La₂O₃ was 90.8 m·s^-1 at φ=1.0， which was 46.7% higher than that of the undoped Al/CuO thermite （61.9 m·s^-1）. The ignition temperature of Al/CuO thermite was also raised when La₂O₃ was added. It is suggested that La₂O₃ improved the gas production performance of Al/CuO thermite to varying degrees. The peak pressure of Al/CuO thermite formulated at φ=1.0 and φ=1.8 increased by 34.5% and 13.7%， respectively. The effect of equivalent ratio at φ=1.4 on peak pressure of Al/CuO thermite was unclear. The combustion results indicated that doping La₂O₃ will alter the flame propagation mode of Al/CuO thermite. The combustion state was observed to be changed from deflagration to slow combustion with the increase of La₂O₃. The inclusion of La₂O₃ in Al/CuO thermite is suggested to be used as a means to control the propagation velocity and energy release.

Abstract:Hyphenated techniques of thermal analysis， including common thermogravimetric-differential scanning calorimetry （TG-DSC）， thermogravimetric-infrared/mass spectrometry （TG-FTIR/MS）， Fourier transform infrared spectroscopy/solid-state in situ reaction techniques （Thermolysis/RSFTIR） and thermogravimetric-infrared-mass spectrometry （TG-FTIR-MS）， are effective ways to study the thermal decomposition properties and mechanisms of energetic materials. Compared to the single thermal analysis techniques， the hyphenated techniques of thermal analysis are more adequate， efficient and comprehensive ways to evaluate the thermal behaviors and thermal stability and to reveal the thermal decomposition mechanism of energetic materials. A comprehensive and in-depth study of the physicochemical properties of energetic materials by hyphenated techniques of thermal analysis is of great practical significance and value in improving and enhancing the performance of energetic materials in applications. Herein， this paper presents a comprehensive review of the advance in the application of TG-DSC， TG-MS， TG-FTIR-MS， TG-FTIR-GC-MS and Thermolysis/RSFTIR hyphenated techniques in the study of energetic materials. The research contents， important results， features and advantages of these techniques are analyzed， and related perspectives are presented， such as developing high-performance computational analysis software， solving the problems such as the deconvolution of overlapping mass spectral peaks in mass spectral analysis， and introducing a new extension system in the thermal analyzer to expand the scope of their application， thus providing technical support for the thermal analysis of new energetic materials.

Abstract:Sequential solidification process has a great application prospect in casting explosives. In order to study the correlation between process parameters and charge quality， a simulation study of sequential solidification process was carried out， based on the moving boundary modeling method， where TNT/RDX （33.8/65） was taken as an illustration example. The effects of process parameters， such as water injection speed（0.15， 0.20， 0.25 mm·s^-1）， water temperature（30， 40， 50 ℃）and preheating temperature（60， 70， 80 ℃）， on temperature field and shrinkage defects in the solidification process were studied， based on three-factor orthogonal tests， and a optimized process parameter program was obtained. It can be seen that water injection speed has the greatest impact on charge solidification quality， followed by the water temperature and preheating temperature of mold. Compared with experimental program（water injection speed is 0.15 mm·s^-1， water temperature is 50 ℃）， preheating temperature is 70 ℃）， the optimized program of orthogonal tests（water injection speed is 0.15 mm·s^-1， water temperature is 50 ℃， preheating temperature is 60 ℃） reduces the shrinkage volume by 74%. This implies that the matching of process parameters is an effective method in improving charge solidification quality in the future. The simulation results and experimental design methods in this paper can provide references for process parameter matching optimization of charge solidification.

Abstract:The Laser-induced Air Shock from Energetic Materials （LASEM）， a laser-induced air shock performance test method based on milligram-scale energetic materials on microsecond time scales， was combined with a pulsed laser system and high-speed ripple shadowing. The effects of different particle sizes and different stacking densities on the characteristic velocities of shock waves from five energetic materials （CL-20， HMX， RDX， FOX-7， LLM105） were investigated. The results show that when the particle size is less than 75 μm， the measurement results deviation is large. When the particle size is in the range of 75-500 μm， the measurement results are less volatile and consistent with the order of the burst pressure value， which can be used as reference data to assess the actual burst performance. When the bulk density is less than 0.7 g·cm^-3， the measurement results fluctuate in a wide range. When the bulk density is in the range of 0.7-1.35 g·cm^-3， the measurement results are more stable and consistent with the order of the burst pressure value， and thus the measurement value is more valuable.

Abstract:Molecular dynamics simulations were used to investigate the effects of a series of vacancy defect concentrations （0%， 1.56%， 6.25% and 12.5%） on the sensitivities， mechanical properties and bursting properties of dihydroxylammonium 5，5"-bistetrazole-1，1"-diolate （TKX-50）. Firstly， perfect crystal model and vacancy defect models were first constructed， and the correctness and validity of the Dreiding force field used in the study were verified. Then the models were geometrically optimized and molecular dynamics simulated， and the trajectory files to reach thermodynamic equilibrium were statistically and analytically analyzed. It was found that vacancy defects lead to decreases in the cohesion energy density and in the number of total hydrogen bonds of TKX-50， indicating that TKX-50 containing vacancy defects has increased susceptibility and decreased safety. And with the increase of vacancy defects， the number of hydrogen bonds between hydroxylamine cations remains almost constant， and the number of hydrogen bonds whose hydrogen bond acceptor is oxygen atom on bitetrazolium anion is significantly reduced compared with other hydrogen bonds. Besides， the vacancy defects reduce the bulk modulus （K）， elastic modulus （E）， and shear modulus （G） of TKX-50 by 1.530-4.122 GPa， 3.066-10.652 GPa， 1.216-4.202 GPa， respectively. It indicates that the stiffness of TKX-50 crystal decreases with the increase of vacancy defect concentration. The positive Cauchy pressure （C₁₂-C₄₄） of all models indicates that all models exhibit ductility， and the values of K/G and Poisson"s ratio （γ） increase with the increase of vacancy defect concentration， indicating that the toughness and plasticity of TKX-50 are enhanced by the increase of vacancy defects. In addition， the vacancy defects also reduce the detonation velocity and detonation pressure of TKX-50 by 93-317 m·s^-1 and 1.0~3.5 GPa， respectively， indicating that the damage power of defect crystals is reduced.

Abstract:In order to study the safety protection issues and explosion characteristics of colloidal charge structure under high temperature environment， the charge structure consisting of a thermally insulating outer layer， an endothermic colloid and an emulsion explosive was designed. The effects of three colloid proportions and two sensitizing modes （emulsion explosives were sensitized by sodium nitrite and expanded perlite respectively） of explosive in the charge structure on thermal insulation and explosion performance were studied by physical property measurement， thermometric analysis， explosion testing technology （underwater explosion， detonation velocity experiment， near-field detonation pressure measurement） and field experiment （sympathetic detonation， blasthole blasting）. The results show that the colloidal material containing 0.5% high molecular water-absorbent resin is suitable for the charge structure， attributing to the fire resistance， high specific heat and low thermal conductivity， which extends the thermally insulating protection time to 55 min. In underwater explosion and detonation velocity experiments， as the heating time of 100 ℃ water bath increases， all detonation parameters （peak shock wave pressure， specific impulse， detonation velocity， and total explosive energy） of the charge of two sensitizing modes decrease. Affected by the demulsification of emulsion explosive and the reduction of sensitization hot spots， the detonation performance of emulsion explosive sensitized by sodium nitrite （EE-SN） is attenuated greater than that of emulsion explosive sensitized by expanded perlite （EE-EP）. After heating for 2 hours， the total explosive energy loss of EE-EP and EE-SN is 4.76% and 17.62%， respectively. In the near-field explosion pressure measurement of colloidal medium， the colloidal layer in charge structure will weaken the strength of explosion shock wave. However， the blasting effect is good in the field experiment， and the charge structure has realized the 30 mm sympathetic detonation and the stable detonation propagation in the blast hole， indicating that the colloidal charge structure has a good application prospect for high-temperature blasting.

Abstract:The polymer bonded explosive （PBX） model containing different coating structures is established based on the peridynamics theory and Voronoi method. The dynamic damage behaviors of PBX under different impact speeds are simulated. The simulation results indicate that double-layer coating structure can better protect HMX crystal compared to single-layer coating structure. For single-layer coating structure， the damage mode is mainly transgranular fracture. By contrast， the damage is dominated by intergranular fracture in the case of double-layer coating structure. Moreover， for double-layer coating structure， the quantitative results on damage ratio of HMX is obtained and the performance of different coating structures is ordered. By analyzing the stress state of HMX， it is found that the coating structure can greatly impact the stress distribution. This study can help better design the coating structures in PBX.

Abstract:The polymorphic transformation （PT） and control technology of hexanitrohexaazaisowurtzitane （CL‍-20） has been a hot area of research in energetic materials， which is also the key issue must be addressed to promote its application. In order to further understand the PT characteristics and mechanism of ε‍-CL‍-20 with different crystallization characteristics， the PT laws and isothermal PT kinetics of ε‍-CL‍-20 were studied based on in‍-situ X‍-ray powder diffraction （XRD） technology. The effect of surface and internal defects on the ε→γ PT behavior of CL‍-20 was discussed. The isothermal PT kinetics of ε‍-CL‍-20 with different crystallization characteristics was analyzed and the related parameters were calculated. The results show that temperature is the dominant factor affecting the solid‍-solid PT of ε‍-CL‍-20. For the conventional particle ε‍-CL‍-20， with the increase of internal and surface defects in the crystal， the initial temperature of PT decreases and the PT rate increases. Compared with 100 μm CL‍-20， ultrafine （0.5-1 μm） ε‍-CL‍-20 has higher starting temperature of PT， but its PT rate is also faster. The abnormal PT behavior of ultrafine ε‍-CL‍-20 is explained from the two‍-sidedness of crystal defects. When CL‍-20 undergoes ε→γ PT under thermal stimulation， both the surface and internal defects of the crystal have an induction effect on the PT process， and the γ crystal preferentially nucleates at the defects such as vacancies， impurities or dislocations with low nucleation barrier on the ε‍-CL‍-20 crystal， and then gradually grows up at these positions.

Abstract:In order to study the influence of degree of cone angle， cone diameter and thickness of conical liner on shaped charge jet effect and optimize the structure of liner， orthogonal test with three factors and four levels was designed. ABAQUS software was used to simulate the shaped charge jet to penetrate the target， and weighted gray correlation method was used to analyze the orthogonal test results of jet target penetrating. The correlation degree between the angle， diameter and thickness of the cartridge and the effect of jet target penetrating was obtained. The results show that the cone angle has the greatest effect on shaped charge jet， and the cone diameter and thickness have the secondary effect. The parameter combination of liner for the best shaped charge jet target penetrating is： cone angle 61.2°， cone radius 18 mm， thickness 1.05 mm. Using the best combination of parameters， the maximum velocity of the shaped charge jet is 5855 m·s^-1， the depth of the penetrating target is 59.43 mm， and the opening diameter of the penetrating target is 8.24 mm. The research results can provide theoretical guidance for the application of shaped charge jet penetration.

Abstract:Modular artillery charge system （MACS） is one of the main charge structures for large-caliber howitzers. To accurately study the interior ballistic characteristics of single modular artillery charge system and analyze the variation law of gas flow and pressure wave in the chamber， a combustion experiment platform for MACS was designed to carry out the combustion experiment of single modular artillery charge system. According to the characteristics of modular artillery charge system， the axisymmetric two-dimensional two-phase flow interior ballistic model of modular charge was constructed in different regions. Based on the high-order accurate Monotonic Upstream-centered Scheme for Conservation Laws （MUSCL）， the numerical simulation of the ignition process of single-module charge was carried out. The results show that the calculated results are in good agreement with the experimental results. The calculated maixmum errors of the pressures at different test points are less than 4%， indicating that the mathematical model established and calculation method used can describe the combustion process of single modular artillery charge system well. The results also show that before t=5.0 ms， the combustion of the module cartridge has little effect on the internal flow field of the module. The gas of main propellant can"t diffuse into the charge chamber in time due to the obstruction of the end cover of the cartridge.Only the gas of the ignition tube has a certain effect on the flow field in the chamber. The maximum pressure in the chamber during this period is about 4.3% higher than that before the right end of the fire tube is not broken. After the rupture of the cartridge， there is a pressure difference of 3.05 MPa at the boundary between the cartridge and the chamber， so that the propellant gas and solid particles flow rapidly along the axial direction to the free space of the chamber. A strong reflection of the pressure wave is formed at the bottom of the projectile. After that， the pressure wave oscillates repeatedly and gradually weakens.

Abstract:In order to explore the effects of explosive environments on the oxidation and combustion of aluminum nanoparticles （ANP）， the mechanisms of high temperature combustion of ANP in nitroglycerin （NG）， 1，3，5-trinitro-1，3，5-triazine （RDX） and 1，3，5-triamino-2，4，6-trinitrobenzene （TATB） environments under different heating methods were studied by molecular dynamics simulation. The results show that the oxidation capacity of NG， RDX and TATB to ANP reduces in order， and the different explosive environments have different effects on the microscopic mechanism of combustion. As the oxidizability of explosive environment becomes weaker， the degree of ANP crack weakens at rapid heating， and with the oxidation becomes slower， the main coordination number of Al atom in final formed Al cluster decreases from 7 in NG environment to 6 in TATB environment. Besides， the dissociated Al atoms from ANP form some large Al clusters with about 100 atoms in the TATB environment， which also inhibits the oxidation of ANP. There is little difference on the number of Al clusters between different explosive environments at programmed heating. However， the number of Al clusters formed after ANP cracks is less as the oxidizability of the explosive environments decreases at constant heating and adiabatic heating. The number of Al clusters continues to increase in a short time thereafter due to the reason that the small Al clusters are less likely to agglomerate in a weakly oxidizing environment. ANP in NG environment mainly reacts with the oxygen-containing products decomposed from explosives， and the formed Al clusters are oxidized more completely. Nevertheless， ANP could react with N₂， CN and other oxygen-free products in RDX and TATB environments， which leads to the formation of Al clusters containing C， H and N atoms， and thus the oxidation of Al clusters is not complete.

Abstract:To determine the compatibility of 3，4-Dinitrofurazanfuroxan （DNTF） with different polymeric passivators， models of fusion-cast explosives were constructed. These fusion-cast explosives were mixtures of DNTF with polymethyl methacrylate（PMMA）， fluororubber （F₂₆₀₃）， cis-butadiene rubber （BR）， or polyvinylidene fluoride （PVDF）. The molecular dynamics （MD） simulation method was used to study the compatibility between DNTF and the above-mentioned four polymer passivators from the radial distribution function， solubility parameter and Flory-Huggins interaction parameter under the COMPASS force field. The nature of the intermolecular interaction force in the blends was revealed. The compatibility of the four blend systems was further experimentally verified by using the vacuum stability tests （VST）. The results show that the intermolecular radial distribution function values for individual components are lower than that between two different components in the blends. The solubility parameters of these systems are less than 3 J^1/2·cm^-3/2. The interaction parameter values of the systems are less than the critical interaction parameter value. The outgassing volume of these systems are all less than 0.6ml， indicating that DNTF is compatible with PMMA， F₂₆₀₃， BR and PVDF. The numerical simulation results are well consistent with the experimental results.

Abstract:In order to study the effect of polymers such as polyolefin， polyester， polyurethane and polyether on the mechanical properties of DNAN and its mixed explosives， the physical miscibility of different polymers with DNAN was studied by X-ray testing， in which polymers were microcrystalline wax（WAX）， polyisobutylene（PIB）， polybutylene succinate（PBS）， polyadipic acid hexanediamine（PA） and poly（3，3-di（nitrate ester methyl） oxybutyl）（PBNMO）. The solidification process of the polymer-containing samples was observed by microscopic. The dynamic crystallization characteristics of the samples during solidification were analyzed， and the linear velocity of crystal growth was calculated. Based on the optimized polymer， the influence of polymer content on the mechanical strength of DNAN and its mixed explosives was studied by material testing machine. The mechanical strengthening mechanism of polymer to DNAN and DNAN based explosives was analyzed. The results show that PBS， PA and PBNMO have good mutual solubility with DNAN under the action of hydrogen bonds or π bonds. The addition of fusible polymer makes the solid-liquid interface of DNAN crystals smooth and the solidification linear velocity decreases by more than 54%. Among them， the PBNMO has the most obvious improvement on the crystal morphology and solidification linear velocity of DNAN. PBNMO could significantly improve the mechanical properties of DNAN and its based explosives， and the mechanical strength increases with the increase of polymer content. When the polymer PBNMO content was 2%， the tensile strength and shear strength of DNAN based explosives increase more than 100%. The mechanism study shows that the fusible polymer can improve the mechanical properties of DNAN-based explosives by improving the microstructure of the sample and forming the “reinforced concrete” structure to reduce the internal defects and improve the crack growth resistance.

Abstract:In order to accurately understand the mechanical characteristic of 1，3，5-triamino-2，4，6-trinitrobenzene （TATB）-based polymer bonded explosive （PBX） under compressive loading， an in-situ measurement technique based on micro X-ray computed tomography （μ-CT） imaging and digital volume correlation （DVC） was proposed. The in-situ scanning for TATB based PBX sample under uniaxial compression was carried out by using μ-CT and the three-dimensional digital volume images of the samples under different loading were obtained. Then， two sets of digital volume images obtained before and after loading respectively were analyzed by using local DVC method based on the Inverse Compositional Gauss-Newton （IC-GN） algorithm and the three-dimensional internal displacement and strain fields with sub-voxel accuracy were obtained. The internal stress fields were finally rebuilt according to the elastic Hook’s rule. The results show that the generation and development process of the strain localization zone inside the sample could be directly revealed based on the internal measurement technique combining DVC and μ-CT. In addition， the Zero-mean Normalized Cross-Correlation （ZNCC） coefficients are commonly lower at the microcracks. In practical applications， the location of sub-voxel microcracks could be identified by the distribution of ZNCC coefficients.

Abstract:To study the fundamental physical properties and intermolecular interaction of energetic materials under the loading temperature， the first-principle calculation was performed combined with zero-point energy and temperature effect corrections. The accuracy of lattice parameters at experiment temperature （173 K） can be significantly improved， and the deviations between the calculated lattice parameters and available experimental data are within 1%. The unit cell volume change with temperature is relatively reasonable compared with the experimental value at 0-500 K， and their deviation is mainly from the lack of interactions between phonons. Furthermore， the basic thermodynamic properties such as heat capacity， entropy and bulk modulus were predicted， and the results indicate that the lattice parameters and thermal expansion coefficient of FOX-7 have strong anisotropy in 0-500 K. Especially， the thermal expansion coefficient of interlayer direction is higher than that of inner layer direction， which is closely related to the molecular configuration and stacking. Importantly， when the temperature reaches 200 K， the shrinkage of thermal expansion coefficient of FOX-7 is related to the rotation of NO₂ group. The NO₂ group would regulate the intermolecular interaction by changing the dihedral angle with the molecular plane， thereby triggering potential phase transformation of FOX-7. In addition， the bulk modulus under the adiabatic conditions is consistent with the experimental values reasonably， and the evolution of adiabatic bulk modulus with temperature reflects the softening behavior of FOX-7 at the finite temperature. With the increase of temperature， the calculated heat capacity and entropy increase gradually， showing obvious numerical differences under the constant volume and pressure due to the anharmonic effect.

Abstract:To study the relationship between shear band and brittle-ductile transition behavior of typical polymer bonded explosives（PBX） under the influence of temperature， the mechanical response of PBX at 323-363 K was tested by using DIC digital image technology， in-depth analysis of shear band evolution law and failure mode. At the same time， the brittle-ductile transition mechanism of PBX under temperature effect was analyzed based on the theoretical model of crack slip. And the critical conditions of wing crack development and plastic slip area were obtained by considering the effect of temperature. The results showed that at 323-363 K， the variation of the shear band width of the PBX depended on the competition mechanism of dilation and shrinkage. There are four main mechanisms： Ⅰ. Dilatation and shrinkage reach equilibrium； Ⅱ. Shrinkage is dominant； Ⅲ. Dilatation is the main controlling factor； Ⅳ. Dilatation dominates intermittently. Combined with the principle of Griffith energy release， it is found that the shear strength， cohesion and fracture toughness of the specimen are the key controlling factors of the brittle-ductile transition. Under the condition， the judging basis of PBX brittle-ductile transition was obtained. When the condition of wing crack instability was met， the macroscopic failure mode tends to split failure； and when the critical condition of the plastic slip area was achieved， the multiple slip zones are connected to each other to form a plastic slip surface， and the macroscopic failure mode was dominated by the ductile fracture of shear crack slip.

Abstract:In order to study the law of crack initiation， growth and evolution of explosives under weak load. The numerical simulation of crack initiation and evolution of explosives was carried out by using the material model considering the phenomena of tensile and compressive anisotropy with strain rate effect. The numerical results are in good agreement with the test data， and the applicability of the numerical model is verified. The typical characteristic images of crack generation and evolution of explosives were obtained through a series of numerical simulations， and the effects of initial crack size， loading rate and loading position on the crack propagation process of explosives were also analyzed， which can provide reference for the analysis of damage and fracture process as well as the dynamic response of explosives.

Abstract:To explore the effect of magnetic field on the explosion characteristics of premixed gas and its mechanism， taking ethylene as an example， the influence law of magnetic field on the explosion characteristics of premixed ethylene/air was experimentally studied. The chain reaction process of ethylene explosion was numerically simulated. The influence of magnetic field force on key free radicals was theoretically analyzed. The transient pressure of ethylene explosion was measured by pressure sensors and the flame propagation velocities were measured by explosion velocity apparatus. Results show that under the maximum magnetic field intensity of 3300 Gs， the maximum explosion pressure of 6.5% ethylene decreased by 18.18% and the explosion pressure rise rate reduced by 17.33%. Along the flame propagation direction， the magnetic field firstly promoted and then suppressed the flame propagation speed of ethylene explosion， in which the suppression effect was greater than the promotion effect. The ethylene explosion was simulated by Chemkin-pro software， and the key free radicals in ethylene explosion were obtained. Different types of free radicals have different intensities of magnetization. Force of free radical under magnetic field is proportional to magnetization of free radical. The magnetic field force has a greater impact on free radicals with high magnetization， and no impact on anti-magnetic substances. Different types of free radicals appear stratification phenomenon under magnetic field. The collisions between different types of free radicals were reduced， and the elementary reaction rate was decreased， which suppressed the ethylene explosion.

Abstract:In order to treat the harmful acid wastewater from the refining process of 3-nitro-1，2，4-triazol-5-one （NTO）， the basic ion exchange resin was used to treat the wastewater and recover NTO. The resin with better adsorption effect was screened among four commercial resins（D301，D201，D311，IRA402）， and the effects of adsorption time and initial concentration on the adsorption of NTO by the resins were studied. In the dynamic adsorption experiment， the pH， initial concentration and flow rate of the simulated wastewater were screened to obtain the best adsorption conditions， and the desorption agent with better effect was screened. Five repeated experiments of adsorption and desorption were carried out under optimal conditions， and the desorption solution was acidified and extracted to recover NTO. The results show that D301 wet resin has good adsorption capacity for NTO， and the adsorption curve conforms to Langmuir equation. The theoretical saturated adsorption capacity can be inferred from the equation to be 232 mg·mL^-1. When the initial concentration of the simulated wastewater is 8 mg·mL^-1， the flow rate is 3 BV·h^-1， and the pH is 3， the adsorption effect of D301 is the best， and the saturated adsorption capacity is 205 mg·mL^-1. The resin is desorbed by 10% NaOH solution， and the best desorption rate can reach 98%. In repeated experiments， the recovery rate of NTO is 82%-88%， indicating that the resin has stable performance and can be recycled. In conclusion， the method of using basic ion exchange resin to adsorb NTO in wastewater is feasible and has practical application prospect.

Abstract:The production and processing of pyrotechnics produce aniline wastewater， which causes a great pollution to the environment. To provide an efficient strain resource for aniline degradation， a strain Q6 with aniline as the only carbon source and energy growth was isolated from the activated sludge in the aerobic aeration tank of the chemical wastewater treatment plant. Through morphological observation， physiological and biochemical characteristics and 16S rDNA gene sequence phylogeny analysis， the strain was identified as Acidovorax sp. The effects of inoculum amount， temperature， pH value and additional carbon and nitrogen sources on aniline degradation by strain Q6 were studied. Meanwhile， the degradation kinetics of aniline at different initial concentrations and the growth kinetics of strain Q6 were fitted. The results showed that under the conditions of temperature 23-37 ℃ and pH 5-8， strain Q6 could degrade aniline efficiently， and ammonium chloride was the best co-metabolizing nitrogen source to promote the degradation of aniline.The optimum conditions of 33 ℃， pH 7 and inoculation amount of 10%， the degradation rate of aniline at different initial concentrations （200-3000 mg·L^-1） was above 95.0%， and the degradation process of aniline showed first-order and zero-order kinetics. The growth process of Q6 conformed to the Haldane equation with a maximum specific growth rate μ_max of 0.130 h^-1， a half-satiation constant K_s of 190 mg·L^-1 and the inhibition constant K_i of 8497 mg·L^-1. The results show that strain Q6 has unique potential in the treating industrial wastewater containing high concentration of aniline.

Abstract:The special polycylic cage structure of the typical third-generation energy-containing material hexanitrohexaazoisowoodsane （CL-20） makes its production process accompanied by high concentration of organic solvents， which has large biological toxicity. In order to solve the serious pollution emission caused by CL-20 production. A combined internal electrolysis-alkaline hydrolysis-biodegradation process was proposed. Firstly， nitro compounds were reduced by zero-valent. Ethyl acetate and chloroform could be decomposed to small molecular organic acids by alkaline hydrolysis. Then， organic pollutants in wastewater were removed by anaerobic-aerobic biological combination process. The results indicated that CL-20 in the wastewater was thoroughly removed at the optimal reaction pH of 2. For alkaline hydrolysis process， the optimal pH value and treatment time was found to be 11.0 and 4 h， respectively. The removal efficiencies of ethyl acetate and chloroform reached （99.4±0.1）% and （95.4±0.9）%， respectively. Biodegradability could be improved by internal electrolysis-alkaline hydrolysis pretreatment. The chemical oxygen demand （COD） in effluent could be as low as 300 mg·L^-1 during the integrated biological process of upflow anaerobic sludge reactor （UASB） and biological aerated filter （BAF）. The combined internal electrolysis-alkaline hydrolysis-biodegradation process offers bright prospects for the treatment of wastewater from the manufacture of CL-20.

Abstract:A method of determination of hydrazine， monomethylhydrazine （MMH）， and unsymmetrical dimethylhydrazine （UDMH） in water by hydrophilic interaction chromatography （HILIC） coupled with mass spectrometry （MS） was developed. Sample preparation， composition of mobile phase and parameters of MS detection were investigated for optimization for HILIC-MS analysis of hydrazine compounds. 80% isopropanol-0.1% formic acid was used as sample solvent， and injection volume was 10 μL. Composition of mobile phase was 70% acetonitrile-10 mmol·L^-1 ammonium formate， pH=3.5. Hydrophilic interaction chromatographic column was utilized for separation. Protonated non-covalent adduct of hydrazine and acetonitrile， protonated MMH and protonated UDMH were selected as detection ions， and post-source collision energy were 50， 100， 100 eV， respectively. Good linearity between MS response intensity and analyte concentration for quantitative analysis was obtained in certain range of analyte concentration. The limits of detection for hydrazine， MMH and UDMH were 0.04， 0.005， 0.025 mg·L^-1， respectively. Recovery of spiked water sample was determined as 92%-115%.

Abstract:The wastewater generated in the production process of dinitrotoluene（DNT） is characterized by complex composition and difficult biodegradation. In this study， the idea of O₃/Fe（Ⅱ） oxidation enhanced by high gravity to degrade actual DNT wastewater was proposed. The effect of operating parameters on DNT wastewater removal was studied， and the catalytic mechanism of O₃/Fe（Ⅱ） oxidation degradation of DNT enhanced by high gravity was revealed. The intermediate products in DNT degradation process were analyzed， and the degradation pathway was speculated.The results showed that the increase of the high gravity factor facilitated the deep degradation of nitro compounds， and the pH of the system affected the direct and indirect oxidation reactions of ozone and the concentration of catalyst Fe（Ⅱ）. Under the conditions of high gravity factor （β）of 40， the Fe（Ⅱ） concentration of 0.8 mmol·L^-1 ， the O₃ concentration of 60 mg·L^-1 ， liquid flow（Q_L）of 80 L·h^-1 and pH of 1.1， 60% of nitro compounds were removed after the reaction for 60 min. Under similar operating conditions， the removal rate of nitro compounds was 18.30% higher than that of the bubbled reactor （BR） O₃/Fe（Ⅱ） system. The electron paramagnetic resonance spectrum showed the relative peak intensity of 1∶2∶2∶1， indicating the existence of hydroxyl radical （·OH） ， confirming that the degradation process followed the catalytic mechanism of ·OH. The intermediates of DNT degradation in rotating packed bed（RPB）O₃/Fe（Ⅱ） system mainly include dinitrobenzaldehyde， dinitrobenzoic acid， dinitrobenzene， resorcinol， malonic acid. The degradation pathway of Fe（Ⅱ）-catalyzed ozonation of dinitrotoluene was speculated.

Abstract:Due to the actual application requirement for Unsymmetrical Dimethylhydrazine（UDMH） degradation， low temperature plasma（LTP） was employed as an efficient proposal. An application device based on dielectric barrier discharge（DBD） was designed and developed with microsecond pulse power supply and six coaxial reaction tubes as the key components to generate LTP for UDMH degradation. The effects on the discharge power and power factor of power parameters were explored under different frequencies and pulse widths. Under optimal conditions， the removal efficiency of UDMH and the energy consumption were analyzed. The power factor of the experimental device increases with the increase of frequency， and has a maximum value between 2 μs and 10 μs， which is near 6 μs. The optimal parameters for power supply is the input voltage of 200 V， frequency of 1000 Hz and pulse width of 6 ms. The removal efficiency of 43.5 and 264.5 mg·L^-1 UDMH reached 99.9% and 93.8%， and the energy consumption was 0.51 and 0.18 kWh·g^-1. Therefore， the coaxial reaction tube with quartz glass and water film as barrier medium and air as the working gas can generate large-area LTP through DBD， which can degrade UDMH efficiently with low energy consumption， indicating that LTP technology has good practical value for UDMH wastewater treatment.

Abstract:In order to verify the applicability of time-temperature-stress principle in tensile creep of TATB-based PBX and realize the evaluation calculation of long-term uniaxial tensile creep deformation， the conventional tensile creep experiment under constant stress but different temperatures and multistep tensile creep experiment under constant temperature of a TATB-based PBX were carried out. The tensile creep curves under constant temperature but different stresses were obtained by decomposing the multistep creep curve following Chen"s method. The coupled creep compliance master curves under reference temperature and stress （30 ℃ and 3.0 MPa） and parameters of Willianms-Landel-Ferry equation considering temperature and stress were obtained by translating and assembling the creep compliance curves using dichotomy calculation program based on the time-temperature-stress equivalence of nonlinear viscoelastic materials. The results show that the tensile creep behavior of TATB-based PBX is well described by the time-temperature-stress equivalent principle in the analyzed temperature range from 30 ℃ to 50 ℃ and stress range from 1.0 MPa to 5.5 MPa， which could be used to predict the long-term tensile creep deformation under low temperature and low stress through the short-term tensile creep tests at high temperature and stress.

Abstract:Aluminized explosives have been widely applied due to their high energy density and pressure output. To further enhance the secondary combustion reaction and pressure output of aluminized explosives， graded structure is designed inspired by the microstructure of bamboo. In this work， the radially-graded structured HMX/Al （RGS-HMX/Al） cylinders with three layers containing different sizes and content of Al were prepared through 3D direct writing technology. The effects of Al distribution on combustion and pressure output properties of graded HMX/Al were fully studied. For the RGS-HMX/Al cylinder with Al content of 10%， 20%， and 30% distributed from inner to outer layer， the combustion reaction and flame propagation of inner layer were faster than that of outer layer. And the pressure （2337.61 kPa） was higher than that of RGS-HMX/Al cylinder with Al content in the reverse distribution. For the RGS-HMX/Al cylinder containing Al of 10 μm， 5 μm， and 160 nm distributed from inner to outer layer， a slow combustion process with sparse bright Al droplets was observed. Moreover， the highest peak pressure （1512.65 kPa） was obtained for the RGS-HMX/Al cylinders with nAl in the middle layer， which exhibited much higher pressure output than that homogeneous HMX/Al cylinder. More importantly， bimodal pressure was observed for the RGS-HMX/Al cylinders with Al of 10 μm in the middle layer.

Abstract:In order to explore the effects of structure on combustion performance of aluminum/polytetrafluoroethylene （Al/PTFE）-based reactive materials and improve combustion performance of fluorine-based thermite， additive manufacturing technology （3D printing） was utilized to prepare Al/PTFE-based reactive materials with solid， hollow， core-shell， and confined hollow structures， as well as Al/CuO-based and Al/Fe₂O₃-based reactive materials with confined hollow structures. The microstructure， thermal performance， combustion rate， and gas production performance were assessed by scanning electron microscope （SEM）， differential scanning calorimetry （DSC）， high speed camera， and constant volume combustion chamber. The results show that each sample exhibits intact structure and uniform components. Under the circumstance of same mass， the samples with core-shell and confined hollow structures display lower heat release than that of samples with solid and hollow structures. The burning rate of samples with hollow， core-shell， and confined hollow structures is 1.44， 1.32， and 2.62 times higher than that of samples with solid structure， respectively. Obvious improvement in gas production performance and pressurization rate appears for samples with hollow and confined hollow structures， especially for samples with confined hollow structure. The burning rate of Al/PTFE， Al/CuO， and Al/Fe₂O₃ materials with confined hollow structure is significantly higher than that of corresponding samples with solid structure， particularly for Al/Fe₂O₃ materials. The approach to regulate combustion performance of lines by preparing materials with hollow structure is expected to provide a novel idea for designing new high-performance weapons.

Abstract:The structural integrity evaluation of the metal-explosive bonding interface is of great importance and engineering value. To realize high sensitivity detection of interfacial debonding defects in the metal-explosive structure， the ultrasonic detection and imaging methods based on multiple pulse-echoes was proposed. The acoustic impedance and reflection characteristics at bonding interface of aluminum， shellac， and RDX were calculated and analyzed. For specimens with different adhesive layer thickness and artificial prefabricated debonding defects， debonding information were extracted from the captured multiple echoes. The influence of adhesive layer with different thickness on the amplitude of multiple echoes was discussed and analyzed. Results show that dramatical amplitude difference exists in the reflected waves between the aluminum-adhesive and the aluminum-water interface. Both the first echo and multiple echoes could effectively distinguish the area with and without adhesive layer. The acoustic attenuation caused by the aluminum-adhesive interface keeps accumulating in high order echoes. As the thickness of the adhesive layer increases， the cumulative effect of the acoustic attenuation difference in the multiple ultrasonic echoes between aluminum-adhesive and aluminum-water interfaces gradually weakens. Experimental results show that the minimum debonding defects with Φ1.5 mm circular and 1 mm wide rectangular shape could be detected using multiple ultrasonic echoes method.

Abstract:In order to study thermal shock damage characteristics of small-size polymer bonded explosive （PBX） hemispheres， 0-100 ℃ water-bathed thermal shock test was carried out for Φ10 mm TATB based and HNS based PBX hemispheres. 3D morphology and distribution characteristics of the damages in the PBX hemisphere were studied by X-ray micro-computed tomography，and the thermal conduction and thermal stress of the sample during the thermal shock process were simulated and analyzed by using the 2D axisymmetric thermal elastoplastic model. The CT results show that the two kinds of samples both started to crack from hemisphere corner， in which the cracks in TATB based PBX hemisphere propagate in a circumferential direction along the edge， with tortuous shape and characteristics of tearing and brittle fracture； The cracks in HNS based PBX hemispheres basically penetrate along the axial direction， with the morphology of straight and characteristics of brittle fracture. The simulation results show that strong tensile stress is generated in the in the hemisphere of TATB based PBX during temperature. And the tensile stress from hemisphere corner to hemisphere center region successively exceeds tensile strength， resulting in the initiation of the main cracks from the edge of hemisphere and propagated inward. The damage characteristics of the sample is consistent with the stress distribution characteristics and the temperature characteristics of the binder under temperature shock. This study lays a foundation for the analysis of temperature shock damage mechanism of TATB-based and HNS-based PBX.

Abstract:In order to study the effect of Mg（BH₄）₂ on thermal stability of nitramine explosives， the thermal decomposition properties of Mg（BH₄）₂/RDX， Mg（BH₄）₂/HMX and Mg（BH₄）₂/CL-20 were investigated by differential scanning calorimetry （DSC）. Thermal decomposition products of three mixtures were analyzed by Thermogravimetric analysis-Fourier transform infrared spectroscopy coupling technique （TG-FTIR）. Results show that Mg（BH₄）₂ has different effects on the thermal decomposition and apparent activation energy of three kinds of nitramine explosives， in which the heat release of RDX and CL-20 increases by 14.7% and 32.1% respectively， and but that of HMX decreases by 45.8%. The apparent activation energies of RDX decreases by 15.8 kJ·mol^-1， while that of HMX and CL-20 increases by 19.7 kJ·mol^-1 and 11.5 kJ·mol^-1， respectively. The thermal decomposition products of three kinds of nitramine explosives are the same （mainly NO₂ and N₂O） whether there is Mg（BH₄）₂ or not. Mg（BH₄）₂ has little effects on the thermal decomposition products and the contents of HMX and RDX， but caused the apparent water peak of CL-20. The concentration ratio of NO₂ to N₂O decreased by 89.2%， indicating that Mg（BH₄）₂ promotes the thermal decomposition of RDX and CL-20， and inhibits the thermal decomposition of HMX.

Abstract:The effect of crosslinking catalyst Copper 2，4-glutarate-cyclooctadiene complex dosage on the properties of polytriazole-crosslinked solid elastomer was studied. Propargyl-terminated ethylene oxide-tetrahydrofuran copolymer （PTPET）was used as an adhesive and polyazide compound as an curing agent， a series of polytriazole-crosslinked solid elastomers S1-S4 were prepared by adding crosslinked catalysts of 0.01%， 0.02%， 0.05% and 0.10%. The chemical structure， thermal stability， mechanical properties and network structure of polytriazole-crosslinked solid elastomers were characterized by FTIR， TG， equilibrium swelling method and DMA. It was found that PTPET elastomer is more stable than PET elastomer， the dosage of the catalyst did not influence the thermal stability of the elastomer， and the decomposition temperature for all samples is at 405 ℃. The elastomer S2 with 0.02% crosslinking catalyst has the most perfect network structure and the best mechanical properties， and the glass transition temperature is -67.4 ℃.

Abstract:In order to improve the stability of α-AlH₃， acidic and organic solutions were used as modifiers to treat α-AlH₃. Through structural characterization， stability test， and mechanical sensitivity test， the properties of samples before and after the treatment were compared and analyzed. The performance on hydrogen release and the corresponding modification mechanisms were compared， and the modifier with a better stabilizing effect was obtained. The experimental results show that the proposed modification methods are effective and have a negligible effect on the hydrogen release properties of the studied samples. The weight loss associated with hydrogen release observed for the modified α-AlH₃ does not exceed by 1%， and the changes in initial temperature and peak temperature of hydrogen release are less than ±3 ℃， the maximum hydrogen release rate is not affected by more than 20%. Treatment by hydrobromic acid solution exhibited the best effect on enhancing the storage stability of α-AlH₃， and the amount of hydrogen release for the studied samples during the storage was found to decrease from 0.87% to 0.02%. It suggests that the acidic and organic solution treatment can reduce the impurities and defects on the surface of α-AlH₃ sample， and the amorphous alumina or aluminum hydroxide are likely to be formed on the surface of α-AlH₃ after the acidic solution treatment which enhances the stability of α-AlH₃. Compared with organic solutions， the acidic solution treatment shows a better ability to maintain the hydrogen release properties of α-AlH₃， enhance its storage stability， and reduce mechanical sensitivity， which can be used as a promising modifier in practical applications.

Abstract:In order to study the uniaxial tensile mechanical properties of hydroxyl tetrade propellant under wide temperature and confining pressure， the mechanical properties of propellants under different temperatures（-50 ℃， 20 ℃ and 70 ℃）， confining pressures（0.1， 2 MPa and 8 MPa） and tensile rates（100， 1000 mm·min^-1 and 4200 mm·min^-1） experiments were conducted by using a wide-temperature-confining pressure gas test system. The internal microscopic reasons for the development of macroscopic mechanical properties were analyzed by means of scanning electron microscopy （SEM） and micron CT， with the main of revealing the influence mechanism of external load on mechanical properties of high solid content propellants. The results show that the damage of propellant is mainly attribute to“de-wetting” at room temperature and high temperature. At low temperature and atmospheric pressure， the particles suffer the "de-wetting" and ductile fracture. When the confining pressure increasing， it would change to brittle fracture of particles. Nevertheless， the elongation still increases with the increase of confining pressure. Under high confining pressure and different tensile rates， the mechanical properties of the propellant at room temperature and high temperature are similar. Because at this conditions， high temperature weakens the interaction between binder matrix and solid filler， and the “de-wetting” of the propellant are more seriously， but high confining pressure inhibits the “de-wetting” and weakens the influence of temperature. When the time-pressure equivalent superposition principle （TPSP） is used to carry out the fitting analysis of the principal curve of the maximum tensile strength， at low of -50 ℃， the relationship between the time-pressure displacement factor and the corresponding confining pressure does not conform to the standard form， and the superposition principle of TPSP has certain limitations for the use of high solid content propellants.

Abstract:To explore the detailed thermal decomposition properties of the mixture system consists of ammonium perchlorate-based molecular perovskite energetic material （H₂dabco）（NH₄）（ClO₄）₃ （DAP-4， where H₂dabco²⁺ refers to 1，4-diazabicyclo［2.2.2］octane-1，4-dianiumion） and dihydroxylammonium 5，5"-bistetrazole-1，1"-diolate （TKX-50）， the thermal decomposition characteristics and gas products of DAP-4 and DAP-4/TKX-50 mixtures were comparatively analyzed by using differential scanning calorimetry-thermogravimetry/mass spectrometry/fourier infrared spectroscopy； meanwhile， the changes of characteristic groups in the condensed phase of DAP-4 and DAP-4/TKX-50 mixtures with temperature were investigated by in-situ FTIR. Based on the explorations the thermal decomposition mechanism of DAP-4/TKX-50 mixture was proposed. The results showed that after mixing DAP-4 with TKX-50， DAP-4 had little effect on the thermal decomposition of TKX-50， while the heat generated by the thermal decomposition of TKX-50 made the reversible phase transition endothermic peak of DAP-4 disappeared， but hardly affected DAP-4′s thermal decomposition at high temperature. The thermal mass loss of DAP-4/TKX-50 mixture was divided into two stages. The mass loss of the first stage was 43.4% and the mass loss of the second stage was 52.4%， leaving 4.2% of the decomposition residue. The main gas products produced by thermal decomposition of DAP-4 and DAP-4/TKX-50 mixture were NH₃/H₂O/HNCO/HCN/CO/HCl/CO₂ and H₂O/NO/N₂O/HCl/NH₃/N₂/HNCO/HCN/CO/CO₂， respectively. The thermal decomposition mechanism of the DAP-4/TKX-50 mixture was proposed as follows： the reversible transfer of hydrogen ions occurs first in the molecule of TKX-50 to generate hydroxylamine and 1，1"-dihydroxy-5，5"-bitetrazole （BTO）， then hydroxylamine decomposed into small molecular gases at high temperature while the fragments generated by BTO decomposition partially polymerized into coupling products. Finally， the ionic bond of DAP-4 was broken， leading to instantaneous collapse of the cage-like skeleton. The strongly reducing and strongly oxidizing gas components underwent violent redox reactions at high temperatures and release a large amount of heat.

Abstract:3，3′-Diamino-4，4′-azofurazan （DAAzF） is one of the main impurities that produced during the synthesis of 3，3′-diamino-4，4′-azoxyfurazan （DAAF）. However， the effect of DAAzF on the thermal performance of DAAF remains unclear in the past. To this end， a doping strategy based on the dissolution-precipitation method was developed to prepare DAAF@DAAzF explosives by uniformly doping 0.5%-10% DAAzF into DAAF， and the effect of DAAzF on the thermal performance of DAAF@DAAzF explosives was investigated by using simultaneous thermogravimetry and differential scanning calorimetry. The doping of DAAzF decreases the melting point of DAAF-based explosives， with the greatest decrease from 246.4 ℃ to 239.3 ℃ occurring at 10% DAAzF content. For the first time， it is found that the eutectic mixture can be formed when the mass ratio of DAAzF/DAAF is 5/95. Further， the presence of DAAzF decreases the activation energies and pre-exponential factors of DAAF-based explosives during the initial decomposition. Therefore， DAAzF as an impurity accelerates the thermal decomposition of DAAF@DAAzF explosives and reduces their thermal stability.

Abstract:Polymer Bonded Explosive （PBX） is a multiphase composite material composed of pure explosive particles occupying a high volume fraction and a little polymer binder. The interface debonding between particles and binder and the mesostructure play a critical role in the mechanical properties of the material. In this paper， according to the stochastic simulation method combined with the Voronoi method， the representative volume element model of PBXs is established at the mesoscale. When the particles generated by Voronoi method are multi-graded， the particles around the large ones show a strip-scattering shape. The method of mesostructure modeling of PBXs was improved based on Voronoi method. Considering the mesoscopic interface characteristics of PBX-9501， the interface damage evolution between particle and binder under static tension was numerically simulated by using the constitutive relationship of three-stage bonding interface. The results show that the macroscopic mechanical properties of PBX-9501 agree well with the experimental data. The relationship between convergence and the size of representative volume element is discussed. It is concluded that the larger the size of the representative volume element is， the worse the convergence of the interface debonding simulation is.

Abstract:To explore the curing reaction behavior of 3，3-bis（azidomethyl）oxetane-tetrahydrofuran copolyether （PBT） and toluene diisocyanate （TDI） binder system， the effects of curing temperature， curing ratio and plasticizer on the curing reaction of PBT-TDI system were investigated by microcalorimetry， and the curing reaction kinetics and thermodynamics of PBT-TDI system were studied and analyzed. The experimental results show that： （1） the higher the curing temperature and the higher the TDI content， the faster the curing reaction； （2） increasing the amount of plasticizer bis（2，2-dinitropropyl）acetal/bis（2，2-dinitropropyl）formal （A3） and dioctyl sebacate （DOS） would reduce the curing reaction speed of the PBT-TDI system； （3） the curing reaction of the PBT-TDI system fits well with the n-th order reaction kinetic model with an activation energy of 12.81 kJ·mol^-1 and a pre-exponential factor of 1.48×10^-2 s^-1.

Abstract:Meriting in green and pollution-free combustion products， large specific surface area， insensitive-safety ， large contact area with reactants and easy modification， nanocarbon has been widely focused on tuning the performances of energetic materials （EMs） such as high explosives， propellants and thermites. This work reviews the effects of nanocarbon on the decomposition characteristics， sensitivity， mechanical performances and combustion properties of EMs. In addition， it discloses the progresses in the detection， adsorption and degradation of EMs conducted by nanocarbon. The interaction mechanisms of typical nanocarbon materials （nano-diamond， fullerene， nanocarbon fiber， carbon nanotube and graphene） in EMs have been analyzed. Within this review， issues， challenges and promising research directions existing in the application of nanocarbon in EMs are highlighted and presented. （1） Optimizing the high-cost preparation processes of nano carbon. Easy agglomeration and large batch differences of nanocarbon. （2） Expanding the application scope of nanocarbon. Exploring the effects of new-type nanocarbon such as onion carbon and modified nanocarbon on the properties of energetic materials. （3） According to the specific environment and nanocarbon regulation mechanism， the application conditions of nanocarbon in improving the properties of energetic materials are optimized. It is expected that nanocarbon materials will provide a forum for future advancement in the modifications of multifunctional EMs.

Abstract:To investigate the effect of deuteration on the vibrational properties of chemical bonds of triacetone triperoxide （TATP） and its thermal decomposition behavior， TATP and deuterated triacetone triperoxide （TATP-d₁₈） were prepared by using acetone and acetone-d₆ as raw materials， respectively， with hydrogen peroxide acting as the oxidant source and sulfuric acid as the catalyst. TATP and TATP-d₁₈ were characterized by nuclear magnetic resonance spectroscopy （NMR）， Fourier transform infrared spectroscopy （FTIR） and differential scanning calorimetry （DSC）. The non-isothermal reaction kinetic parameters of TATP and TATP-d₁₈ were calculated with Kissinger， Ozawa， and Friedman methods. The results show that the deuteration of TATP results in an evident red-shift phenomenon， and the ratio of the stretching frequencies of C—H（D） bonds （ν_C—H/ν_C—D） is about 1.36. The apparent activation energy of TATP-d₁₈ （E_K=80.54 kJ·mol^-1， E_O=83.56 kJ·mol^-1， E_F=72.27 kJ mol^-1） is higher than that of TATP （E_K=67.91 kJ·mol^-1， E_O=71.01 kJ·mol^-1， E_F=63.79 kJ·mol^-1）， indicating that TATP-d₁₈ has higher thermal stability. The calculated thermal explosion critical temperatures for TATP （T_b=402.37 K） and TATP-d₁₈ （T_b=423.46 K） also confirm that deuteration improves the thermal stability of TATP-d₁₈. Finally， the calculated thermodynamic parameters for the non-isothermal decomposition processes of TATP and TATP-d₁₈ indicate that TATP and TATP-d₁₈ would not spontaneously undergo thermal explosions.

Abstract:To prevent the agglomeration of cobalt ferrite （CoFe₂O₄） nanoparticles and improve their catalytic decomposition performance for Octogen （HMX） and HATO （TKX-50）， graphitic carbon nitride （g-C₃N₄） was applied as CoFe₂O₄ nanoparticles dispersant carrier. The in suit preparation of CoFe₂O₄/g-C₃N₄ binary nanocomposites were achieved through solvothermal method. Corresponding composition， structure morphology and catalytic decomposition performance of CoFe₂O₄/g-C₃N₄ were investigated through X-ray powder diffractometer， scanning electron microscopy， fourier transform infrared spectrometer and differential scanning calorimeter. The results showed that the morphology of CoFe₂O₄/g-C₃N₄ composites is uniform and dense， which reduces the thermal decomposition peak temperature of HMX and TKX-50 by 7.0 ℃ and 41.3 ℃， respectively， and the apparent activation energy by 341.1 kJ·mol^-1 and 21.0 kJ·mol^-1， respectively. Moreover， the introduction of g-C₃N₄ increases the heat release amount. The results of residue analysis showed that the catalytic decomposition of HMX was very complete， while TKX-50 presents incomplete catalytic decomposition， and its residua formed micron bulk mixtures with CoFe₂O₄/g-C₃N₄.

Abstract:In order to establish a precise combustion heat measurement system and method suitable for energetic materials， a method and device for measuring the heat of combustion of energetic materials with tiny doses has been developed. This device is based on the thermal principle of differential heat flux and uses a three-dimensional thermopile consisting of 960 pairs of thermocouples as the core measuring element. The device was calibrated by using standard material benzoic acid. The heat of combustion of six typical energetic materials， including cyclotetramethylene tetranitramine， hexanitrohexaazaisowurtzitane， cyclotrimethylene trinitramine， 3，4-bis（3-nitrofurazan-4-yl）furoxan， 1，1-diamino-2，2-dinitroethylene and nitroguanidine， was measured by this device. The results show that the calorimetric coefficient of the instrument is （64.804±0.071） μV·mW^-1 and the corresponding relative uncertainty is 0.109%. The solid-phase standard molar heats of combustion （Δ_cU） of these six energetic materials at 298.15 K are -（2749.1±4.5）， -（3593.6±6.0）， -（2115.2±3.4）， -（3040.8±4.8）， -（1211.4±2.3） and -（898.4±2.0） kJ·mol^-1， respectively. The measurement results are in good agreement with the values reported in the literature， indicating that the developed small-mass combustion measurement device can be widely used in the determination of the energy of combustion of substances containing C， H， O， and N， especially precious samples and explosive substances.

Abstract:（C₆H₁₄N₂）［Na（ClO₄）₃］ is a representative of energetic perovskite compounds. It is necessary to clarify the corresponding thermal decomposition behavior， thermal decomposition mechanism and sensitivity characteristics in order to promote the application in formulations. Thermal decomposition parameters， including heat release amount and decomposition temperatures， were obtained by simultaneous differential scanning calorimetric and thermogravimetric analyses methods. The relevant decomposition mechanism was analyzed by kinetic simulation calculations. The decomposition products and decomposition processes of （C₆H₁₄N₂）［Na（ClO₄）₃］ were explored by DSC/TG-FTIR-MS coupled technique combined with in-situ infrared technology. The parameters of thermal sensitivity， friction sensitivity and impact sensitivity were obtained by national military standard methods. The results show that the heat of decomposition of （C₆H₁₄N₂）［Na（ClO₄）₃］ is 4227 J·g^-1 at the heating rate of 10 ℃·min^-1 and the decomposition temperature reaches 345 ℃， which is higher than that of most active energetic materials， including Hexogen （RDX）， ogen （HMX） and hexanitrohexaazoisowuzane （CL-20）， indicating an outstanding thermal stability. The decomposition products analysis shows that the cubic cage-like skeleton effectively stabilizes the internal organic molecule， resulting in the high thermal stability of （C₆H₁₄N₂）［Na（ClO₄）₃］. In addition， the outgassing amount of （C₆H₁₄N₂）［Na（ClO₄）₃］ heated at 100 ℃ for 48 h is about 0.04 mL·g^-1， and the impact sensitivity and mechanical sensitivity are 32% and 80%， respectively， which are better than RDX and HMX.

Abstract:To solve the problems of igniting difficulty and combustion agglomeration， modification of Al powder by alloying and oxidant coating was studied. AP@Al/Ni composite fuels were prepared by acoustic resonance mixing technique. The heats of reaction of the composite fuels with different ammonium perchlorate （AP） contents were measured using a bomb calorimeter. The morphology characteristics of the optimized AP@Al/Ni composite fuel were analyzed by SEM. The thermal reactivity of AP， Al/AP mixture， Ni/AP mixture， and AP@Al/Ni composite fuel were comparatively studied by DSC/TG. The effects of additives including Al， Ni， and Al/Ni composite on the thermal decomposition kinetic parameters of AP were evaluated by the non-isothermal kinetic method. The results show that the heat of reaction of the composite fuel reaches its maximum when the mass content of AP is 38.90%， which is considered as the optimal content of AP in the formula. Compared with Al and Ni， the Al/Ni composite has the most significant influence on the thermal decomposition of AP， which reduces the peak temperature of AP in high temperature decomposition by 76.9 ℃ and increases the heat release by 84.8%. The apparent activation energy of AP decomposition in AP@Al/Ni composite fuel that obtained by Friedman method is 103.9 kJ·mol^-1， and this process obeys the three-dimensional random nucleation and nucleus growth （A3） model.

Abstract:To evaluate the aging performance of acrolein-pentaerythritol resins （123 resins）-RDX based casting polymer bonded explosive （PBX）， accelerated aging tests were performed according to MIL-STD-1751. The microstructure and aging mechanism of casting PBX during aging were investigated by in-situ Infrared Spectroscopy （IR）， 3D-Super Depth of Field Digital Microscope and Scanning Electron Microscope （SEM）. After aging 260 days at 65 ℃， the mass and size change rates of the casting PBX columns are both within 0.25%， which is better than the standards （<1%） of U.S. military standard MIL-STD-1751. The results indicate that PBX columns are stabilization at an acceptable level after aging tests. In addition， no obvious variations on both surface and corss-sectional morphology are observed， except for color changes. The interface between RDX particles and the binder is still well bonded， and the cross section is mainly transgranular fracture. The mechanical properties including both compressive strength and tensile strength of 123 resins-based casting PBX increases obviously with the increase of aging time. After aging 60 and 150 days at 65 ℃， the compressive strengths increase by 6.42 MPa and 13.69 MPa with the increasement of 8.46% and 18.05%， respectively. After aging 90 and 180 days at 65 ℃， the tensile strengths increase by 0.78 MPa and 1.13 MPa with the increasement of 6.34% and 9.19%， respectively. The mechanism of the mechanical properties’ increase was studied by in-situ IR method and the post-casting behavior during aging process was considered as the main reason.

Abstract:The safety performance and initiation process of explosives are closely related to their high-temperature and high-pressure behavior. Therefore， it is of great significance to study explosives under high-temperature and high-pressure thus understanding their safety and initiation performance in depth. The structural evolution of twelve explosives under high-temperature and high-pressure is reviewed， including common nitroamine-based explosives represented by RDX and HMX， common nitroester-based explosives represented by PETN，nitro-based explosives represented by TNT， and new high-energy and low-sensitivity explosives represented by LLM-105 and TKX-50. The phase transformation processes of these explosives under high-temperature and high-pressure are summarized in detail， and the similarities and differences of the research results from different research teams on the same material are compared. This review provides a strong basis for the studies of structural evolution of explosives under high-temperature and high-pressure.

Abstract:In order to increase the energy of the secondary reaction of composite explosives， the novel composite oxidant ammonium perchlorate （AP）-lithium perchlorate （LiP） was prepared by solvent evaporation method. Scanning electron microscope （SEM） and X-ray diffractometer （XRD） were used to test and characterize the morphology， and crystal structure of the sample. The thermal decomposition properties of the samples were analyzed by differential scanning calorimetry （DSC）. The underwater explosion power parameters of three polymer bonded explosives （PBXs） containing composite AP-LiP， mechanical mixture AP-LiP and AP were evaluated by electrometric method. The results show that， for composite AP-LiP， the crystal morphology is fairly regular， the crystal surface is smooth， the particle size distribution is fairly uniform， and no agglomeration is observed. Composite AP-LiP has a high degree of crystallization and a fairly complete crystal structure. The thermal decomposition performance of composite AP-LiP is better than that of mechanical mixture AP-LiP. The underwater explosion results show that， compared with the AP-containing PBX， the shock wave energy， bubble energy， and total energy of underwater explosion of PBX containing composite AP-LiP increase by 0.098-0.154， 0.254 MJ·kg^-1 and 0.352-0.408 MJ·kg^-1 respectively， and the energy decays slower as the distance increases.

Abstract:In order to study the thermal decomposition properties of the characteristic groups of 3，4-Dinitrofurazanylfuroxan （DNTF）， differential scanning calorimetry （DSC） and fast scanning Fourier transform infrared spectroscopy （FTIR）were adopted to study the thermal decomposition properties of DNTF in condensed phase. The changes of characteristic groups of DNTF were studied by using FTIR technology at three different heating rates of 2.5， 5.0， 10 ℃·min^-1. The thermal decomposition kinetic parameters of C─NO₂， furazan ring， and furoxan ring of DNTF were calculated by the Coats-Redfern method. The thermal decomposition mechanism of DNTF was inferred based on the thermal decomposition properties of the characteristic group of DNTF. The results show that the thermal decomposition of DNTF is controlled by the three-dimensional diffusion mechanism. The reactivity of groups in DNTF molecule is nitro>furoxan ring>furazan ring. With the increase of heating rate， the reactivity of each group shows an increasing trend. It is speculated that the thermal decomposition process is that C─NO₂ breaks first， and then the C─C bond connecting furuzan and furoxan ring breaks， and finally the N─O bond in furazan ring and furoxan ring breaks. The furoxan ring decomposes faster than furazan ring.

Abstract:ReaxFF molecular dynamics （ReaxFF MD） simulations were adopted to identify the main intermediate products， final products and chemical reactions during 3，4-dinitro-1H-pyrazole （DNP） thermal decomposition. Accelerating rate calorimeter （ARC）-mass spectrometer （MS） technique was adopted to study DNP thermal decomposition properties and identify the gaseous products. The simulated results illustrate that C₃HO₄N₄， C₃HO₃N₄， C₃HO₂N₃， C₃HNO₂， NO₂ are the main intermediate products， and H₂O， CO₂， N₂ are the main final products. MS detected main gaseous products are H₂O， CO₂， N₂ as well. According to the simulation results， the produced time and abundance of the products are obtained as well. Among which C₃HO₃N₄ is the first generated intermediate product， and H₂O is the first generated final product. C₃HO₃N₄ and N₂ are the intermediate and final products with the largest amount， respectively. Additionally， the main chemical reactions in DNP thermal decomposition process are also acquired by molecular dynamics simulations. According to the generation time and abundance of products， the decomposition path of DNP was obtained.

Abstract:In order to explore the thermal decomposition behavior of 3，5-dimethyl-4-hydroxyphenylpentazole， UV-visible light absorption spectrum combined with quantum chemical calculation was adopted. The thermal decomposition of 3，5-dimethyl-4-hydroxyphenylpentazole （HMPP） with increasing temperature was tracked. The thermal stability of HMPP was tested by differential scanning calorimeter. The results show that the initial decomposition temperature of HMPP is -14 ℃， and the characteristic absorption peak produced by the pentazole ring is at 284 nm in the UV-visible region. The characteristic absorption peak of 3，5-dimethyl-4-hydroxyphenyl azide （HMPA） is 258 nm. With the increase of temperature， the absorption peak of the whole system decreases gradually at 284 nm. In order to explore the specific reasons for the change of HMPP ultraviolet-visible light absorption spectrum， the decomposition products of HMPP were separated by column chromatography. The main decomposition products of HMPP were 2，6-dimethyl-p-benzoquinone and 4-（4-hydroxy-3，5-dimethylphenyl） amino）-2，6-dimethylcyclohexa-2，5-diene-1-one. After the thermal decomposition of HMPP， the uV-visible absorption of the whole system was determined to be caused by the superposition of uV-visible absorption of compounds 4 and 5.

Abstract:Laminated composite charge is composed of two or more different charges by way of superposition， in which the safety and power performance can be regulated through the design of charge structure. To study the sympathetic detonation safety of laminated composite charge， typical composite charges which contain both the high energy charge and insensitive charge were selected as research objects. The effect of different charges structure on critical sympathetic detonation distance was explored through numerical simulation and sympathetic detonation tests. Results showed that， compared to simple high energy charge， the sympathetic detonation of composite charge decreases 53.3%（from 7.5 mm decreases to 3.5 mm）， while energy decreases 22.9%. The thickness of insensitive charge must reach a certain threshold（3 mm） in order to reduce the critical sympathetic detonation distance obviously. As the content of insensitive charge increases， the critical sympathetic detonation distance is closer to insensitive charge.

Abstract:To investigate the influence of temperature-induced phase transition of polytetrafluoroethylene （PTFE） on the fracture toughness of Al-PTFE reactive material， the quasi-static tensile test and fracture toughness test were performed， and the normalization data reduction technique with single specimen in ASTM E1820 was applied for analyzing the elastic-plastic fracture toughness of Al-PTFE by J-integral method. Combined with the microstructures analysis of the fracture surface， the effect of temperature on the fracture toughness of Al-PTFE was revealed. The results show that the strength of Al-PTFE reactive material decreases with the increase of temperature， while the fracture toughness increases. Moreover， the yield strength and fracture toughness of this material change obviously after crossing the phase transition temperature. The crack propagation pattern changes from brittle fracture to ductile fracture. Furthermore， when PTFE is in phase Ⅱ， less PTFE fibrils can be formed by stretching. However， increasing temperature can lead to the transform of the crystal phase for PTFE to phase Ⅳ and Ⅰ. Besides， the stable formed PTFE fibrils can effectively dissipate the external energy in the form of local plastic deformation. The crack tip is passivated by winding bridging， so as to prevent the crack propagation and improve the fracture toughness of this material.

Abstract:Nano-thermites， as one kind of energetic composites， have wide applications. A systematic study on the relationship between the interface structures and properties has great significance for the preparation of the new nano-thermites with excellent performance. The structures and energies of Fe₂O₃（104） and Fe₂O₃（110） surfaces and the structures， bonding properties， and adhesion work of Al（111）/Fe₂O₃（104） and Al（111）/Fe₂O₃（110） interfaces （AFS1， AFS2， AFS3， AFS4 and AFS5） were studied with the periodic density functional theory in this work. Results show that O-terminated Fe₂O₃（104） and Fe₂O₃（110） surfaces and the interfaces formed by these surfaces with Al（111） are more stable than those of the （104） and （110） surfaces of Fe₂O₃ respectively. Among 5 of the Al/Fe₂O₃ interfaces， the interfaces composed by the O-terminated Fe₂O₃（104） and Fe₂O₃（110） surfaces with Al（111）， i.e.， AFS1 and AFS5， have the maximum adhesion work （3.92 J·m^-2 and 3.02 J·m^-2， respectively）， and AFS1 is more stable than AFS5. In these two most stable interfaces， the Al atoms stack on the top position of the O atoms of the Fe₂O₃ surfaces and the binding of Al and Fe₂O₃ surfaces is mainly through the Al-O ionic bonds.

Abstract:To investigate the thermal hazards of the synthetic reaction process of FOX-7， the heat flow curve of the hydrolysisinvolved therein has been measured by using Reaction Calorimeter （RC1）. The n^th-order kinetic models were applied to different temperature systems and the apparent kinetic parameters of these processes were obtained. The results indicated that the exothermic heat of the synthesis reaction was -46.563 kJ∙mol^-1， and the adiabatic temperature rise was 9.1 K. Under the thermal runaway chemical reaction condition， the maximum temperature of the synthesis reaction （MTSR） is 29.1 ℃. The reaction order is 1.21 for synthesis of 2-（dinitromethylene）-5，5-dinitrodihydropyrimidine-4，6-dione. The activation energy （E_a） of the reaction is 73.2 kJ∙mol^-1， with the pre-exponential factor of 5.03×10⁹ s^-1.

Abstract:In order to study the damage of polymer bonded explosive（PBX） under dynamic shock loads， the constitutive curve of the mechanical damage of PBX under different strain rates was obtained by using the Split-Hopkinson pressure bar（SHPB） test device. And the constitutive parameters in the Z-W-T constitutive model with damage variables were fitted in sections. Then， based on the fitting results， the finite element theory， elastoplastic mechanics and ABAQUS/VUMAT， the subroutine of PBX containing damage is completed， and is verified by the finite element simulation. The model is used for finite element engineering examples. Results show that the verification results of finite element samples are in good agreement with the experimental results， and the correlation degree of the results is higher than 0.95.The stress cloud diagram and damage variable cloud diagram for fragment penetration example reflect the change and possible damage location of PBX under shock loads.The evolution process of damage cloud diagram reflects the correlation between damage evolution and strain rate effect of PBX.

Abstract:Caged energetic compounds are the hotspots in the research field of energetic materials due to their high energy and density levels， and the clarification of their thermal decomposition mechanisms is significant to the in-depth study of their detonation mechanisms and the improvement of their thermal stabilities. Herein， the thermal decompositions of energetic adamantanes， cubanes and isowurtzitanes are reviewed according to the clue of their caged skeletons， and the thermal decomposition mechanisms of these three caged compounds are also summarized. The thermal decomposition of energetic adamantanes initiated from the substituents and possessed Bridgehead Carbon Effect. In contrast， the thermal decomposition of energetic cubanes and polynitroisowutzitanes usually started from the C—C bond in the cage skeleton and the removal of nitro groups， respectively. Future research should further enrich the types of caged energetic compounds and carry out systematic study on thermal decompositions of caged compounds， especially the thermal decomposition mechanisms of the caged skeletons.

Abstract:The thermites with different morphologies performed differently. To explore the influence of different MoO₃ morphologies on the thermal properties and combustion behavior of Al/MoO₃ thermite， Al/rod-MoO₃ and Al/ribbon-MoO₃ thermite were prepared. Field emission scanning electron microscope （FE-SEM）， X-ray diffractometer （XRD） and differential scanning calorimetry （DSC） were used to characterize their morphology and thermal properties. The DSC results showed that the Al/ribbon-MoO₃ thermite had a heat release about 1702 J·g^-1， while the Al/rod-MoO₃ thermite released 432 J·g^-1. The initial reaction temperature of Al/ribbon-MoO₃ thermite was 401.95 ℃， which was 102.92 ℃ earlier than the 504.87 ℃ of Al/rod-MoO₃ thermite. Non-isothermal thermodynamic analysis showed that the activation energy （E_a） of the two thermites was not significantly different， but the Al/rod-MoO₃ thermite presented a higher thermal explosion critical temperature （T_b）， indicating that the Al/rod-MoO₃ thermite exhibited higher safety. In the open combustion experiment， there was little difference in the combustion behavior of the two thermites. When the thermite burnt out， the Al/ribbon-MoO₃ thermite splashed sparks. The closed-tube combustion experiment showed that the combustion wave velocity of Al/rod-MoO₃ thermite increased primely then decreased， and the maximum wave velocity reached 1037 m·s^-1. The combustion wave velocity of Al/ribbon-MoO₃ thermite was on the rise， and the maximum velocity was 2710 m·s^-1. Al/ribbon-MoO₃ thermite is superior to Al/rod-MoO₃ thermite in heat release and combustion performance， but the Al/rod-MoO₃ thermite is much safer.

Abstract:In order to study the influence of structural parameters on characteristics of fragments from warheads with a composite charge， AUTODYN-3D finite element calculation software was used. Next the propagation of detonation waves and shell breaking process of warheads were compared and analyzed， under the central single-point initiation and the internal and external simultaneous initiation. Then the influence of shell thicknesses and central charge diameters on the average mass and velocity of fragments from warheads was obtained. The calculation results show that， with the increase of shell thicknesses or the decrease of central charge diameters， the average mass of fragments under single-point initiation increases more times than that under internal and external simultaneous initiation， and the difference in power output of warheads between those two initiation modes becomes more significant. The static explosion test results show that the average velocity of fragments， shock wave overpressure， and the number of witness target holes under internal and external simultaneous initiation increase 27.1%， 31.4%， and 39.3%， respectively， compared with those under single initiation. The test results are in good agreement with the calculation results.

Abstract:To obtain the reaction characteristics of tetraethylammonium decahydrodecaborate （（C₂ H₅）₄N］₂B₁₀H₁₀，BHN-10） under explosion and shock， the reaction pathways and decomposition products of BHN-10 under shock were studied by electrically exploded plasma shock and explosive blast shock. Results show that the gaseous decomposition products of BHN-10 under electrically exploded plasma shock are organic combustible gases， such as carbon alkanes， alkenes， alkynes， and etc. BHN-10 has good stability under explosive blast shock. The shock wave of 25 GPa magnitude generated by explosive blast cannot promote the decomposition of BHN-10， while the explosion heat is a main factor leading to the reaction of BHN-10. The combustion of BHN-10 occurs under explosive blast shock after 8 ms， and the combustion appears from the central position， lasting for more than 200 ms. The mixture of HMX and BHN-10 has an accelerated diffusion speed of fireball under explosive blast shock， and its combustion time is equivalent to that of BHN-10.

Abstract:In order to determine the parameters of the JWL equation of state for unreacted explosives， a method to determine the JWL parameters by using the BP neural network-Genetic Algorithm （BP-GA Algorithm） and the shock Hugoniot was proposed. Firstly， BP neural network is trained to fit the nonlinear system composed of different JWL parameters， and then Genetic Algorithm is used to search the set of JWL parameters with the largest fitness value. The results show that the JWL parameters can be determined by the BP-GA Algorithm when the initial density， detonation velocity， Hugoniot parameters C₀ and S are known. The p-v curves of eight kinds of unreacted explosives determined by BP-GA Algorithm are consistent with those determined by test data， and the R² of eight p-v curves are not less than 0.9995， which proves the high accuracy of BP-GA algorithm.

Abstract:The hydrodynamic software FLUENT was used to study the drag coefficient of fragments with different initial velocities （≤2500 m·s^-1） and altitudes （≤20 km）， and the velocity attenuation model of fragments with different altitudes was corrected Then the accuracy of the corrected model was verified by the corresponding velocity attenuation characteristic tests with low atmospheric pressures. The results show that the calculated results of spherical fragments with an initial velocity of 700 m·s^-1 and cuboid fragments with an initial velocity of 1000 m·s^-1 using the corrected velocity attenuation model are in good agreement with the experimental results that the errors are less than 5%， and the calculation accuracy of the modified velocity attenuation model is about 10% higher than that of the original model. The corrected velocity attenuation model of fragments can be used to calculate the influence of the drag coefficient， which is varied with the altitude， on the velocity attenuation coefficient of fragments， to improve the calculation accuracy of the fragment velocity， and to further improve the accuracy of the power evaluation of the fragment warhead.

Abstract:In order to ensure the safety of the incineration process， the incinerator must be able to withstand the impact of accidental explosion when the waste energetic materials are incinerated. The dynamic coefficient method and the method proposed by Atomic Weapons Establishment （AWE Method） were used to design the shell of vertical incinerator for waste energetic materials. Then， three-dimensional numerical simulation of the shell stress of the designed incinerator under detonation of energetic materials was carried out using AUTODYN software. The influence of exhaust gas outlet， outlet position and detonation position of energetic materials on the anti-explosion performance of the incinerator was analyzed. Numerical simulation results show that the existence of the outlet destroys the continuity of the shell， therefore， the stress concentration occurs near the outlet， and the maximal stress appears at the upper edge of the outlet. Besides， as the diameter of the outlet increases， as the center of the outlet is closer to the shell cover， and as the detonation position of energetic materials is closer to the outlet， the stress concentration at the upper edge of the outlet becomes more serious. When the energetic material is close to the incinerator shell， the explosion will cause plastic deformation of the shell. Hence， when the diameter of outlet is determined， some measures can be taken to ensure the safety of the incineration process， such as keeping the outlet away from the seal plate， setting a stiffening ring at the outlet and keeping a certain distance between energetic materials and the shell.

Abstract:In order to study the laser radiation effect on Octogen （HMX） crystal， various technical methods were used to characterize the microstructure evolution of HMX crystal under 360 nm ultraviolet laser. By optical microscope， the process from accumulation of defects to cracking under laser irradiation was observed in HMX crystals. In-situ Raman spectroscopy demonstrated that the absorption of UV photons would stimulate HMX molecules， causing the ring vibration. In-situ wide-angle X-ray scattering （WAXS）， single crystal X-ray diffraction （SCXRD） and in-situ small-angle X-ray scattering （SAXS） were also adopted to study the crystal changes and defects evolution of HMX under UV laser irradiation. It is found that phase transformation does not happen but some new defects generate in HMX. The in-situ SAXS results show that the pores in HMX increase continuously after 1170 minutes of laser irradiation and a bimodal distribution exists in the region ranging from 10 to 20 nm and 30 to 40 nm， respectively. During the laser irradiation process， small pores in HMX keep accumulating and gradually merge into larger pores. Due to the accumulation of defects， the microcosmic pores extend into micro-cracks， and then expand into macro-cracks.

Abstract:In order to acquire the mechanical properties and constitutive relations of Zr-based amorphous reactive material under dynamic loading， the specimens were made by pressure infiltration casting， and the dynamic compression experiments under loading with different stain rates were conducted with the split Hopkinson bar （SHPB） test system. The stress-strain curves were acquired under different strain rates of 300-1600 s^-1， and a high-speed camera was used to record the fracture and energy output process of the specimens under different strain rates. Results show that the Zr-based amorphous reactive material belongs to brittle materials that no yielding stage exists in stress-strain curves. With the increase of strain rates from 947 s^-1 to 1587 s^-1， the compressive strength of materials increases from 2.71 GPa to 2.78 GPa with a small increase of 2.6%， while the fracture strain decreases from 0.032 to 0.028 with a decrease of 12.5%. The degree of fracture and reaction of the specimen is more evident with higher strain rate and the strain softening phenomenon occurred during the fracture of materials. According to experimental data， a one-dimensional elasto-brittle constitutive model with damage was fitted for the Zr-based amorphous reactive material before the fracture failure of specimens.

Abstract:Numerical simulation was carried out to study the reaction evolution of explosive charge under weak stimulation and the effect of confinement conditions on its explosion reaction. Based on the multi-media arbitrary Lagrangian-Eulerian method and fluid-structure coupling technique， the numerical simulation of the reaction evolution growth of constrained charge and its interaction with the shell after local ignition were realized. In order to simulate the process from slow burning to violent explosion， a phenomenological model of explosion evolution growth was established. Based on the central ignition experiment of the strongly constrained spherical charge， a series of simulations were conducted and the influence of confinement conditions on the reaction pressure growth process of PBX-2 explosive was analyzed. The results show that the peak value of reaction pressure increases with the increase of shell strength or thickness. When the thickness of the steel shell increases from 5 mm to 20 mm， the peak value of the pressure increases from 163 MPa to 1357 MPa， and the process of pressure increase varies greatly. However， with the fracture and disintegration of the shell， the transformation from explosion to detonation of the explosive charge is restrained.

Abstract:Aiming at the problem of the irreversible deformation mechanism caused by thermal cycling in PBX-9502 （a type of TATB based polymer bonded explosive）， a three-phase microstructure model and an extended finite element method （XFEM） are used to establish a calculation model. The model takes into account the anisotropy of the TATB grains， the local differences in the thermodynamic properties of the bonding agent and its interface. Using the established model， the phenomenon and mechanism of irreversible deformation caused by thermal cycling of PBX-9502 are numerically analyzed. The results show that due to the severe anisotropy of TATB grains in PBX-9502 and the differences in the thermodynamic properties of TATB grains and binders， PBX-9502 specimens have internal deformation and stress concentration during thermal cycling. Resulting in the destruction of the bonding agent and the debonding of the interface and other internal damage to the material， which in turn led to the irreversible deformation of the PBX-9502 specimen under thermal cycling. At the end of the calculation， the axial strain of the PBX-9502 specimen reached 0.2%.

Abstract:In order to investigate the influence of the pitch angular velocity on the penetration trajectory of projectile penetrating into multi-layered target， a large amount of experimental and simulation from literature was analyzed. In the paper， LS-DYNA finite element software was used to simulate the projectile penetrating into multi-layered slabs with or without considering the pith angle velocity. Data obtained in the simulations， like the paper studied the pith angle， landing time， landing speed， landing offset， angle of attack，landing angle， fuse overloading and etc.， were compared with the experimental results. The results show that the numerical simulation was agreed well with the corresponding experimental data， when the pitch was taken into consideration. The influences of pitch with different values and directions on the trajectory of projectile penetration into multi-layered reinforced concrete slabs were analyzed. It shows that， under the same value， the positive pith angular velocity had a greater influence than the negative one. Secondly， in order to ensure that the projectile explode in the target building， the value and direction of the pith angular velocity of the projectile must be controlled between -627°·s^-1 and 427°·s^-1.

Abstract:In order to ensure the safety of field mixed emulsion explosive， dynamic extrusion was used to simulate the charging process of explosive. The stability of field mixed emulsion explosive prepared at different rotating speed was studied by laser particle sizer， microscope， water-soluble ammonium nitrate precipitation test and digital viscometer. The experimental results show that crystallization instability in the emulsion matrix will occur in some extent under dynamic extrusion when the particle size is larger than 5 μm.After 10 times of dynamic extrusion， the amount of ammonium nitrate released from the emulsion matrix is 5.14 times of that before extrusion， the viscosity increases by 43%， and the W/O structure has been completely destroyed.When the particle size is smaller than 5 μm， the dynamic extrusion resistance of emulsion matrix is improved，after 10 times of dynamic extrusion， the particle size of emulsion matrix increased by 2.16 times， the amount of ammonium nitrate released from the emulsion matrix is only 2.14 times of that before compression， the viscosity increased by 10%， and the microstructure remained stable.The dynamic extrusion process will accelerate the crystallization instability of matrix， change the physicochemical properties， reduce the performance of emulsion explosive， and is not conducive to the loading process. In production practice， it is necessary to reasonably control the particle size D≤5 μm.

Abstract:The thermal stabilities and mechanical properties of explosives are important factors affecting the safety of weapons. In order to improve the thermal stability of hexanitrohexaazaisowurtzitane（CL-20） and1，1-diamino-2，2-dinitroethylene（FOX-7） explosives and the mechanical properties of the CL-20 and FOX-7 based PBXs， modified CL-20 and FOX-7 crystals were prepared based on the oxidative self-polymerization reaction of dopamine （DA）. Scanning electron microscope （SEM）， thermal analysis （TG）， dynamic mechanical analysis （DMA）， static contact angle， laser particle size analyzer， high performance liquid chromatography （HPLC）， BMA impact sensitivity， infrared absorption spectrometer and universal material testing machine were used to test the morphology and structure of modified particles， and also the particle size， coating content， sensitivity， thermal decomposition and the mechanical performance of prepared PBX. Results show that DA forms a good polydopamine（PDA） coating layer on the surface of energetic crystals， and different surface coating morphologies can be obtained by adjusting the polymerization time. At the same time， PDA can also improve the interface properties of explosives crystals， which is beneficial to the uniformity of the binder’s distribution. PDA coating inhibits the crystal transformation and increases the activation energy of CL-20， resulting in improved thermal stabilities. The mechanical properties tests showed that the Brazilian strength and compression strength of CL-20 based PBX had been improved by 34.27% and 10.21%， respectively， and the Brazilian strength and compression strength of FOX-7 based PBX had also been improved by 40.44% and 11.92%， respectively. After coating with PDA， the strain of the samples had all increased. In addition， the creep strains of the two explosives were obviously suppressed， leading to enhance creep resistance.

Abstract:Improving the reaction performance of traditional binary thermites is one of the research hotspots in the field of energetic materials in recent years. The introduction of additives to form composite thermite is an effective method. According to the application fields and the different effects of additives， the composite thermites were divided into fuel-enhanced type， gas-producing type and modified additive type. The research status of composite thermite and its related engineering applications were reviewed， and then the new research directions and ideas for composite thermite were proposed， including the use and preparation of new alloy fuels and alloy hydrides， the combined use of non-azide gas generating agents and thermite， the influence of the types and amounts of inert additives， and the coating technology of the binder on the surface of the thermite， etc.

Abstract:To study the energy output law of the suspended AlH₃ dust in explosion and release process， a modified 20 L ball explosion test system was used to study the explosion pressure and flame propagation law in closed and venting conditions alternately. The results showed that the lower explosion limit concentration of suspended AlH₃ in a closed system decreased from 40 g·m^-3 to 30 g·m^-3 comparing with aluminum powder， indicating that the hydrogen released by the burning AlH₃ accelerated the entire chemical reaction process. In addition， both the maximum explosion pressure and explosion pressure rise rate of AlH₃ dust explosion in a closed system were higher than that of the aluminum powder. The maximum explosion pressure rose from 1.02 MPa to 1.15 MPa， indicating that a combustible gas-dust composite system was formed due to the release of hydrogen to exacerbate the violence of the explosion energy release process. Under venting conditions， when the concentration of AlH₃ dust was 500 g·m^-3， the explosion pressure （p） and pressure rise rate （dp/dt） decreased the most， reaching 43% and 30% respectively， indicating explosion venting can effectively reduce explosion damage. Moreover， it was concluded that the length and speed of the explosion vent flame reached the peak values when the concentration of AlH₃ was 750 g·m^-3， meanwhile the probability and frequency of multiple flames presented a positive correlation with the concentration.

Abstract:In order to study the energy output characteristics of three composite explosives containing Mg-based hydrogen storage materials， Ti-based hydrogen storage materials and ZrH₂ hydrogen storage materials respectively， a constant temperature detonation heat calorimeter and an underwater explosion system were used to study the detonation heat and underwater energy characteristics of the explosives. The results illustrated an order of the detonation heat in terms of a thermobaric formulation of RDX/hydrogen storage material/AP/others， which was Mg-based sample>Ti-based sample≫ZrH₂-based sample. Accordingly， the detonation heat for the three explosives were 7587.0606 kJ·kg^-1， 6416.4741 kJ·kg^-1 and 3950.6279 kJ·kg^-1. It was indicated that the detonation heat of the explosives containing hydrogen storage materials was positively correlated with the chemical potential of each hydrogen storage material. In underwater explosions， the explosion parameters including peak pressure， impulse， energy flow density and shock wave energy of the composite explosives presented a similar order， that the Mg-based sample was the best and the ZrH₂-based sample was the worst. Accordingly， the shock wave energy was 1.41 times， 1.26 times and 0.97 times of TNT equivalent for each formula. It was showed that hydrogen storage materials with much higher activity and potential energy could be beneficial for the shock wave in underwater explosion. The contribution to the energy released in underwater explosion of hydrogen storage materials was mainly in the form of bubble pulsation. The bubble energy of the composite explosives containing Mg-based， Ti-based and ZrH₂ hydrogen storage materials were 2.17 times， 1.78 times， and 0.86 times of TNT equivalent respectively， indicating that Mg-based hydrogen storage material had the best energy releasing performance in the secondary reaction， followed by Ti-based hydrogen storage material and ZrH₂was the worst The trends of the explosion parameters of the composite explosives in detonation heat test and underwater explosion test were consistent. The overall energy level of the explosives was in the order of Mg-based sample>Ti-based sample>ZrH₂-based sample. The explosive containing Mg-based hydrogen storage material had the largest energy in underwater explosion， reaching up to 2.02 times of TNT equivalent. The applicability of the ZrH₂ in thermobaric formulation was not strong for both of the energy tested in detonation heat and underwater explosion was lower than TNT.

Abstract:In order to study the influence of modification technology on the ignition and explosion characteristics of the composite hydrogen storage materials， the combustion heat of Al， MgH₂， Hydrogen storage material CM and hydrogen storage material CM-H coated with hydroxyl terminated polybutadiene （HTPB） was measured by an oxygen bomb calorimeter， and the mass change of the four samples within 48 h was test as well. Results show that CM-H has the highest combustion heat for 30.5633 MJ·kg^-1. Meanwhile its mass gained within 48 h in air is the least for 0.46%. Result show that the modification can effectively prevent the performance degradation of the materials so that they can maintain a high combustion heat. The minimum ignition energy， flame propagation characteristics and explosion pressure of the four samples were studied by an 1.2 L Hartmann tube， a high-speed camera and a 20 L ball explosion test device respectively. Results show that the minimum ignition energy of CM is 50-60 mJ， which was only a half of the critical ignition energy of aluminum powder （100-150 mJ）. It indicated that the addition of MgH₂ into metal materials can effectively reduce the ignition energy. The minimum ignition energy of CM-H dramatically increased to 700-750 mJ after coating. The test results of flame propagation speed， explosion pressure and explosion index presented the performance order of MgH₂ > CM > CM-H > Al. Results indicat that the modified composite hydrogen storage material has lower electric spark sensitivity， higher safety and better explosion performance.

Abstract:To investigate the influence of fluororubber coating on the combustion properties of micro-sized aluminum powder （μ-Al）， several methods such as laser ignition，constant volume burning and thermal analysis were employed to study the combustion and thermal performance of 5 μm and 50 μm aluminum powder coated by different content of fluororubber. Ignition delay time， burning speed， state of combustion， combustion heat and thermal reaction properties of these samples were presented. It showed that un-coated μ-Al cannot be ignited by laser in a 0.1 MPa oxygen atmosphere. For the coated 5 μm aluminum powder （5μ-Al@n%FP）， ignition delay time can be reduced from 91 ms to 31 ms， burning speed can also be increased from 3.08 mm·s^-1 to 364.96 mm·s^-1， and combustion heat can reach up to 27.61 kJ·g^-1 by varying the content of fluororubber in the composite particles. Similarly， for the coated 50 μm aluminum powder （50μ-Al@n%FP）， ignition delay time can be reduced from 130 ms to 40 ms， burning speed can also be increased from 1.80 mm·s^-1 to 43.78 mm·s^-1， and combustion heat can reach up to 26.08 kJ·g^-1. Based on thermal analysis （TG）， the reaction depth of fluororubber and the thickness of Al₂O₃ were calculated. It revealed that the reaction between fluororubber and μ-Al occurred merely on the surface of aluminum particles. Under the same reaction condition， the thickness of Al₂O₃ had no correspondence with the size of μ-Al.

Abstract:Aiming at the development and problems of high-strength energetic structural materials （ESMs）， the characteristics， static mechanical behaviors and dynamic mechanical behaviors of high-entropy alloys （HEAs） were summarized and analyzed. The assumptions， potential and challenges of HEAs as high-strength ESMs were proposed and verified from the perspective of both theoretical and experimental aspects. It was found that HEAs had the basic features of “free composition design”， “simple crystal structure with strong lattice distortion” and “high strength and hardness”. At the same time， both static and dynamic mechanical behaviors of HEAs could be adjusted in a wide range by means of process adjustment and composition design. All the above features indicated that HEAs had the potential advantages to be used as high-strength ESMs in terms of workability， high strength， and rapid oxidation to release energy. Existing experimental results also confirmed the application potential of HEAs ESMs. Finally， the challenges faced by the research of high-entropy alloy ESMs and the priorities of future research， such as high-throughput experiments and simulations， researches on dynamic mechanical behaviors and preparation for large-scale samples， were raised based on the intrinsic features of HEAs and previous experimental results.

Abstract:In order to explore the detonation law of α-AlH₃ in condensed phase explosive， the safety features of α-AlH₃ were characterized. The results indicated that α-AlH₃ had poor thermal stability due to its sensitivity to temperature and humidity. The operational condition for α-AlH₃ samples should not exceed 30 ℃ RT and 60% RH. HMX was selected as the main high explosive to develop a formulation containing α-AlH₃ with a self-designed technology namely direct method of step temperature control and cooling. The safety， detonation performance， work capacity and explosion reaction process of the explosive were studied. The molding powder had low mechanical sensitivity and good moldability. When the α-AlH₃ content exceeded 10%， the relative density of the grain decreased with increasing content of α-AlH₃. The characteristic detonation velocity of α-AlH₃ was 6078 m·s^-1. Compared with an HMX based explosive formulation containing aluminum， the counterpart with α-AlH₃ had an equivalent work capacity. But its work capacity was poor at the high and medium pressure stage of the detonation products. The hydrogen element in α-AlH₃ mainly existed in the form of hydrogen in the detonation products.

Abstract:In order to study the influence of aluminum powder on the mechanical property， interface， combustion， safety， energy， density and other performance of propellants， the glycidyl azide polymer （GAP） propellants with 5%， 10%， 15% and 18% aluminum powder were evaluated by tensile testing machine， dynamic thermomechanical analysis （DMA）， calculation program and etc. Results show that， with the replacement of 320 μm AP with 30 μm aluminum powder and the increase of aluminum powder contents， the propellant has increasing maximal tensile strength and maximal elongation， and improving interface performance. The burning rates change scarcely but the pressure indexes drop down from 0.43 to 0.40 under the pressure of 3-9 MPa. The hazard grades of propellants with 5% and 18% aluminum powder are 1.3 both. The impact and friction sensitivities of propellant with 18% aluminum powder are 0% and 44%， respectively， which are lower than the formulation with 5% aluminum powder （4% and 48%， respectively）. At last， the calculation result shows that with the increase of aluminum powder， the energy and density of propellants grow up， but the standard specific impulse levels off to moderate pace of growth.

Abstract:A 20 L explosion device was used to study the explosion characteristics of fuel-air explosive containing micro/nano-aluminum powder. Results indicated that when adding 5% and 10% nano-aluminum to micro-aluminum， the maximum pressure of mixed powder increased by 24.2% and 58.5%， respectively. The maximum rate of pressure rise increased by 80.6% and 103.4%. The nano-aluminum would not have any contribution to the explosion effect while its content was more than 10%. For the fuel with a solid/liquid ratio of 30/70， while the ignition energy increased from 11.83 J to 28 J， the explosion pressure consequently increased from 0.28 MPa to 0.52 MPa， meanwhile the explosion temperature increased from 834 ℃ to 1118 ℃，indicating that the explosion parameters of FAE could be improved by increasing the ignition energy. Increasing the content of micro/nano aluminum powders could effectively increase the explosion pressure and temperature of FAE.

Abstract:How to improve the explosion energy and power ability of explosive by applying reactive metal particles effectively is the key problem for the design of metalized explosive. To explore the application of the micro-B/Al composite powder in enhance blast explosive （EBX） and thermobaric explosive （TBX）， three HMX-based explosives containing B/Al particles were designed and prepared. The energy output characteristics of the samples with a dimension Φ100 mm×105 mm was studied by air blast and underwater explosion tests， meanwhile the power abilities were evaluated by a Φ50 mm cylinder test. The effect of the content of micro-metal on energy output process and power ability of metalized explosives was discussed. Results show that in the air blast and underwater explosion tests， initiated by the detonation of HMX， the combustion of micro-Al can promote the afterburning effect of micro-Boron resulting in releasing a great amount of combustion heat to generate expansible products with high temperature and high pressure， finally increase the sustained duration of fireball and total energy in underwater explosion. In the cylinder test， there was not enough oxygen to react with micro-B before the cooper cylinder burst， accordingly the advantage of combustion energy of micro-boron in explosives containing B/Al could not present. However， after the cooper cylinder burst， the oxygen in the air can oxide B/Al composite powder to release a large amount of combustion heat， which can enhance the power ability of aftereffect.

Abstract:To study the correlation between the packed density of nonmetallic spherical spacers （NSS） and its suppression of propane explosion， a newly designed constant-volume combustion cylinder combined with high-speed schlieren photography was employed. The explosion experiments of propane-oxygen pre-mixtures with different equivalence ratios（1，1.5 and 2） were conducted in cylinders with different packed densities of NSS （21.9 kg·m^-3，38.7 kg·m^-3 and 45.1 kg·m^-3）. The effect of packed densities of NSS on maximum explosion pressures， total heat loss， flame tip velocities， flame propagation characteristics and turbulence in cylinders with different equivalence ratios of propane-oxygen were analyzed in detail. The results show that NSS has suppression effect on the maximum explosion pressure， and has promotion effect on the flame propagation process. When the packed density of NSS is 45.1 kg·m^-3， the maximum explosion descending rate and heat loss in cylinders reach maxima， while the peak flame tip velocity ， the maximum tip velocity difference between two points and the turbulence enhancement factor in cylinders are relatively small， which indicates the best explosion suppression performance of NSS.

Abstract:3， 4-dinitropyrazole（DNP）， a new type of smelt-cast matrix explosive， is a kind of high energy matrix with great application potential. The impact Hugoniot relationship of explosive is the basis to investigate its impact initiation characteristics. For this reason， the pressure comparison method was adopted in this study. Plane wave generators were selected to act the designed loading. The post-shock pressure of DNP explosive and LY12 aluminum samples under nine shock pressures were measured by manganese-copper piezoresistivity gauges. By calculating the experimental data， the velocity （D） of the shock wave and the velocity u of the particle under different pressures were obtained. The D-U relationship of the DNP explosive in the range of 3.7~14.4 GPa was obtained by fitting. The results showed that the Hugoniot relationship of the DNP explosive in the range of 3.7~14.4 GPa could be approximated as a straight line in the D-U plane. The post-wave state of DNP explosive under the action of shock wave was defined， which provided a reference for further study of impact ignition and initiation of DNP explosives. In addition， the influence of polytetrafluoroethylene packaging of manganese-copper piezoresistance gauges on the experimental test results was analyzed. The systematic error caused by packaging was effectively eliminated through theoretical analysis and reasonable interpretation of test signals.

Abstract:The thermal expansion characteristic of explosives under thermal stimulation affects the application of explosives. The thermal expansion characteristic of ［2，2′-bi（1，3，4-oxadiazole）］-5，5′-dinitramide （ICM-101） was studied by using in-situ X-ray powder diffraction， and the thermal expansion coefficient of ICM-101 was obtaind based on Rietveld structure refinement. Results show that there is reversible anisotropic under the high temperature expansion process of ICM-101. In the temperature range of 30-170 ℃， the thermal expansion coefficients of the unit cell parameters a， b， c axis and volume V are 9.19×10^-5 ℃^-1， -9.22×10^-6 ℃^-1， 5.21×10^-5 ℃^-1 and 13.8×10^-5 ℃^-1， respectively. The b-axis exhibits negative expansion characteristics. The unit cell stacking structure of ICM-101 at different temperatures and its correlation with thermal expansion characteristics were studied via the method of molecular spectroscopy technology combined with theoretical calculations. Results show that the compression deformation of the four-membered ring structures of ICM-101 molecules under thermal stimulation is an important reason for the linear negative expansion of the b-axis . Compared with other explosive crystals， the influence of unit cell packing on the thermal stability of explosive crystal structures were analyzed. The thermal expansion anisotropy of explosive crystals with strong hydrogen bonding layered stacked structure is more obvious. When the relative angle between molecules is greater than 100°， the intra-layer hydrogen bonding network affects the interlayer interaction. On the contrary， it will affect the a， b， and c axis directions and limit its thermal expansion.

Abstract:Burning damage technology is an important research area in energetic materials and damage. The research in burning damage technology was mainly reviewed and summarized from three aspects： the formulation design and application of incendiary agents， the damage theory and technology of burning thermal radiation， and the burning damage assessment technology. Problems such as insufficient burning damage effectiveness of incendiary agents， single process of parameter characterization in thermal radiation model and incomprehensive burning damage assessment method were pointed out. The future research emphases on burning damage technology include incendiary materials with high densities and high calorific values，the structure-effect relationship of incendiary agent charges，testing technology for key model parameters represented by the fireball temperature， correction and optimization of thermal radiation damage models， and the accurate assessment method of thermal radiation damage effect under the coupling effect of multiple damage elements in the damage field.

Abstract:The dynamic energy release characteristics of the PTFE-based energetic liner are related to the damage effect of the jet to the target. In this paper， the dynamic overpressure of energetic and aluminum jets in a quasi-closed chamber was measured by static explosion test. The jet energy release and energy release efficiency were obtained by theoretical calculation. The results showed that the energetic liner underwent a deflagration reaction during the forming process， and the overpressure peak of the energetic jet can be increased by 3 times to 4 times compared with that of aluminum jet. For PTFE/Ti energetic liner， in the content range of 0% to 70%， as the tungsten content increased， the jet energy release decreased. But the energy release efficiency was improved due to the increased explosive driving load and the intensified friction between tungsten particles and active metals. For PTFE/Ti energetic liner， in the mass range of 13-30 g， as the mass of the liner increased， the jet energy release was improved. But the energy release efficiency dropped due to the decreased forming pressure of the penetrator.

Abstract:To study the biaxial compressive mechanical properties of solid propellantn， it is necessary to determine the optimal propellant specimen configuration. This configuration should be compatible with the testing machine and test fixture and meetthe requirements of biaxial deformation characteristics. Based on the finite element numerical simulation calculation， the deformation stress contour of the three-component HTPB composite solid propellant specimens with eight different configurations under biaxial compression loading were obtained. Moreover， the optimal propellant specimen configuration was verified by conducting the dynamic biaxial compressive mechanical properties test on the corresponding specimen. Results show that the stress contour of all specimens under small deformation （strain within 10%） is uniform overall. However， the requirement of the plane stress does not meet during deformation of the specimens with an aspect ratio greater than 1. Furthermore， the average value of plane stress， dispersion of plane stress， the whole stress stability factor and the stress concentration factor were selected as the optimizing objective function of the propellant specimen configuration. The contrastive analysis shows that the optimal configuration is a 25 mm cube. Finally， the validity of the above determinated optimal configuration was verified by analyzing the characteristics of stress-strain curves of the propellant specimens obtained under dynamic biaxial compressive loading condition

Abstract:The tandem warhead with high-speed kinetic fragment and coated reactive material has both high-speed penetration and chemical energy damage effect. This paper is aimed to research its tandem damage effect on shielded charges. The impact dynamics model of impacting on shielded charges by the high-speed kinetic fragment and coated reactive material was established. By combining the excitation theory of reactive materials with the initiation criterion of shielded charges， the impact damage to the shielded charges by the high-speed kinetic fragment and coated reactive material was calculated and analyzed. Based on the 2D-Autodyn platform， the initiation process of shielded charges impacted by the high-speed kinetic fragment and coated reactive material was simulated. The comparison verifies the consistency between theoretical calculation and numerical simulation. By Combining theoretical analysis and numerical simulation results， the main influencing factors of the damage to shielded charges， the probable damage modes and the transition conditions between each damage mode were discussed. The results show that there are five damage modes for the shielded charges impacted by the high-speed kinetic fragment and coated reactive material ， including the forepart penetration initiation mode （Ⅰ）， the main part penetration initiation mode （Ⅱ）， the no reactive material reaction and no penetration initiation mode （III）， the reactive material reaction enhanced initiation mode （Ⅳ） and the reactive material reaction and no initiation mode （Ⅴ）. When the structure and material properties are determined， the main influencing factors of damage modes are the impact speed and shielding thickness. The theoretical model established in this paper can predict the above damage modes well.

Abstract:To study the influence of crystal defects on the initial reaction of hexanitrohexaazaisowurtzitane （CL-20）， molecular dynamic simulation and ReaxFF-lg reactive force field are used to study the initial reaction path， thermal decomposition products， and reaction kinetics of CL-20 with vacancy defects at high temperature （1500-3500 K）. The results show that the initial decomposition path of CL-20 with vacancy is the breaking of N─NO₂ bond， the same as that of perfect crystal. The vacancy defects prove to increase the frequency of ring-opening reactions and the production of NO₂. Compared with perfect CL-20， it can be seen that the vacancy defects would reduce the CL-20 activation energy barrier and accelerate its thermal decomposition process. The reaction rate constants of CL-20 with 16.7% vacancies are 1.7 and 1.4 times higher than that of perfect CL-20 at 2000 K and 3000 K， respectively. The CL-20 molecules around the vacancy are easier to decompose， leading to the increase of the sensitivity of CL-20.

Abstract:To study the thermal response of two new DNAN-based aluminized explosives RB-2X（DNAN/HMX/Al/binder） and RM-2X（DNAN/HMX/NTO/Al/binder）， small-scale cook-off experiments and simulations of RB-2X at a heating rate of 1.0 K·min^-1 and RB-2X at heating rates of 1.0 K·min^-1 and 0.5 K·min^-1 were conducted. The numerical simulation used multi-component grid cell calculation method and considered the air gap formed by cooling and contraction of fused cast explosive. The thermal response of explosives were analyzed. The comparisons of ignition time between simulation and experiment show that the ignition time deviation of RB-2X explosive is 1.13%， and the maximum deviation of RM-2X explosive is 5.63%. The influence of the air gap between the explosive and the inner wall of the bomb on ignition time was also analyzed. The results show that the delay time increases gradually with the increase of gap width， and when the air gap expands to 0.75 mm， the delay time is stable at 90 s， indicating that the air gap has a significant influence on the explosive ignition time. The thermal response of large-scale cook-off bomb with RM-2X explosive was predicted. The results show that the temperature at center point can be significantly reduced at ignition by increasing of ammunition size and heating rate. The state of DNAN changes from total melting to solid-liquid coexistence.

Abstract:In order to precisely validate the parameters of detonation reaction rate model of explosives， a HMX/TATB based explosive PBX-1 was the research subject， and the mushroom test was conducted to study the corner-turning performance of explosives with various detonation propagation diameters. Then the mushroom test was simulated by LS-DYNA program with the three-term ignition and growth model calibrated by Lagrangian gauges measurements. The accuracy in calibrated parameters of the reaction rate model was validated by observing the growth and propagation of detonation waves and by comparing the corner-turning parameters. The comparison between experiments and numerical simulations shows that， the mushroom test can reflect the discrepancy of detonation growths of detonation waves in different directions. Finally， it was proved that the parameter validation of the reaction rate model of explosives is feasible by Mushroom test..

Abstract:In order to improve the utilization rate of explosive energy and reduce the mass of welding explosive， it was proposed to use self-restrained explosive to carry out explosive welding research. T2/Q345 weldability window was obtained through theoretical calculations. T2 copper and Q345 steel were respectively used as the substrate and flyer layers， and honeycomb explosive of two layers was used as welding energy to carry out T2/Q345 explosion welding research. The results show that the T2/Q345 composite plate obtained by honeycomb explosive of two layers with self-restrained capability has good bonding performance. Compared with single-layer explosives with corresponding detonation velocities of 2505 m·s^-1 and 3512 m·s^-1， T2/Q345 explosive welding obtained by honeycomb explosive of two layers can save 54.4% and 31.4% explosive by weight， respectively. The honeycomb explosive improves the utilization rate of explosion energy converted into kinetic energy of flyer layer. In addition， with the increase of collision point distance， the interface of the T2/Q345 composite plate changes from flat to wavy.

Abstract:To explore the liquid components of high-potential Fuel air explosive（FAE） with better damage power， taking the traditional typical fuel （propylene oxide） as reference， polymethoxy dibutyl ethe（BTPOM_n）， polymethoxy dimethyl ether （DMM₂）， 1-butanol and 2-butyl alcohol were selected as research object. A pressure testing system， high-speed camera and infrared thermal image were used to record the experimental data. The cloud explosive characteristics of the 5 fuels with 18g RDX as central burster charge and 160g TNT as secondary explosive were studied. The results indicated that the critical initiation energy of the DMM₂was higher than that of the other fuels. The relationship of the damage radius of thermal radiation among 5 fuels was as follows： propylene oxide （18.9 m）＞2-butyl alcohol （16.6 m）＞1-butanol （16.0 m）＞DMM₂ （15.6 m）＞BTPOM_n （12 m）. The damage effects of 5 fuels on people and buildings were evaluated by the PROBIT equation， and the results showed that the damage effects of 1-butanol and 2-butyl alcohol were better than those of BTPOM_n and DMM₂， and the propylene oxide had the best damage effect.

Abstract:In order to study the energy release characteristics of Al/Mg/CuO reactive shells， the images of broken process of reactive shells were observed by an ultra-highspeed rotating-mirror camera， and the shock wave overpressures of varying-sized test bombs were measured by shock wave test system. The reaction time of reactive shell under explosion loads and the effects of particle sizes of reactive materials on shock wave overpressures were analyzed， then the variation of shock wave overpressures with scaled distances was obtained. The results show that reactive shells could take part in explosive reaction and release energy in a few microseconds after detonation reaction. The shock wave overpressures are enhanced and the fireball duration increases more than one time within a scaled distance of 2.52-3.15 m∙kg^-1/3.The overpressure of reactive shell with particle size of 7 μm is 13.3%-14.4% higher than that of reactive shell with particle size of 20 μm，which indicates that reactive materials with smaller particle size can take part in explosive reaction more easily. Compared to bare charges and aluminum shells， the overpressures and impulses of reactive shells rise significantly， increasing 6%-32% and 13%-38% respectively within scaled distances of 2.1-8.4 m∙kg^-1/3.

Abstract:To obtain the influence of submillimeter-sized gap or cushion on the behavior of flyer driven by the detonation of a triaminotrinitrobenzene（TATB）-based explosive， the precise detonation tests with submillimeter-sized gap or cushion were designed. The velocity histories of flyer driven by the triaminotrinitrobenzene（TATB）-based explosive and influenced by the submillimeter-sized gap or cushion were recorded by a laser interferometer （photon Doppler velocimeter）. The results show that the jump-up velocity of the flyer with the influence of submillimeter-sized cushion is lower than the case of flyer attached to explosive， but the final velocity is higher （around 20 m·s^-1 or 1% of the final velocity）. While the influence of submillimeter-sized gap is greater than that of submillimeter-sized cushion that， the final velocity is 50 m·s^-1 （2%） higher than the case of flyer attached to explosive. Simultaneously conducted numerical simulations show that both the point and line initiation conditions do affect the velocity history of the flyer， and the final velocity increases with the influence of submillimeter-sized gap and with either initiation condition. The theory analysis indicates that the introduction of submillimeter-sized gap between flyer and explosive results in weaker interaction between detonation products and flyer for the isentropic expansion of detonation products， and then leads to less entropy increasement of the system， higher energy for driving the flyer， and higher final velocity of the flyer. Additionally， different gap sizes result in different influences as the dominant mechanism varies.

Abstract:To investigate the coupling effect and propagation law of shock wave for underwater array explosion with multiple charges. The shock wave parameters of group charge， two charges and four charges were measured by underwater explosion test. The influence of charge quantity and array distance on peak pressure， impulse and loading time of shock waves were analyzed and revealed the relationship beween array explosion shock wave parameters and distances. The results showed that the shock wave （symmetrical center line） can be superimposed in the focusing direction for two-charge explosion. The shock wave pressure intensity increased by 22.8%-55.4% in the scale distance of 2-6 m·kg^-1/3， and the gain increased gradually with the increase of propagation distance. For four-charge array explosion， the peak pressure of the shock wave in the focusing direction was close to that of group charge. For the same explosion points and layout of the array explosion， the impulse and shock wave loading time can be improved by increasing the array distance. The loading time of shock wave pressure increased with the increase of charge quantity and array distance. For two-charge and four-charge explosion， the peak pressure and impulse of multiple shock waves were still consistent with explosion similarity law， but the loading time of shock wave pressure was not.

Abstract:Ammunitions might experience safety threats of high-temperature heating， high-speed fragment impact， and their combined effects in battlefield. In order to investigate the reaction phenomenon of insensitive explosive PBX-C04 under high-speed impact and the effects of high-temperature and booster charge on this reaction phenomenon， the insensitive explosive safety experiments under high-speed fragment impact were carried out， and the influences of high-temperature and insensitive booster charges（HNS） were considered. Based on the air overpressure， witness plate wreckage and chemical-physical analysis of remained explosives on the scene， the explosive reaction levels of PBX-C04 was assessed comprehensively， and the influences of high temperature and booster charge were studied. The results show that PBX-C04 at room temperature exhibits excellent safety characteristic under high-speed fragment impact， it merely reacted to burning when impacted by a fragment with velocity up to 1970 m·s^-1. When the booster charges of HNS was included， the reaction levels of PBX-C04 correspondingly deteriorated into deflagration. However， when heated to 200 ℃ before impact test， the high-speed impact safety of PBX-C04 equipped with booster charge deteriorated remarkably into detonation.

Abstract:To study the influence of RDX-based metallized explosive components on detonation process，the detonation reaction zone parameters of RDX-based metallized explosives were studied by the interface particle velocity history using photonic Doppler velocimetry （PDV）. Two kinds of RDX-based metallized explosives were granulated， one composition incorporates aluminum （RDX/AP/Al）， and the other incorporates hydrogen storage alloy （RDX/AP/Al/B/MgH₂）. The metallized explosives were initiated by detonation wave， and the detonation reaction zone parameters were analyzed and compared with those of phlegmatized RDX. The results show that the addition of AP/Al component reduced the CJ detonation pressure of phlegmatized RDX from 25.8 GPa to 20.1 GPa. In addition， the detonation reaction zone time （53.6 ns） and length （0.29 mm） of metallized explosives were both higher than those of phlegmatized RDX （24.3 ns， 0.15 mm）. The addition of B/MgH₂ further increased the detonation reaction time （58.0 ns） and length （0.30 mm） of the explosive. The addition of high-energy metal fuel reduced the output pressure of explosives， but increased the detonation reaction zone time and length of explosives.

Abstract:The HNIW/FOX-7-based PBX has been aged 7， 14， 21 d and 28 d at 71 ℃ according to GJB736.8-90 initiators and pyrotechnics test method， respectively. And the morphology and thermal decomposition properties of PBX molding powder before and after aging were characterized. The PBX molding powder was tested by FTIR and XRD. The variations of size， mass and mechanical properties of the PBX columns have been measured before and after aging tests. Results show that the mass and size change rate are both within 1%， which meets the evaluation standard of MIL-STD-1751， indicating that PBX columns are still at an acceptable level after aging tests. The surface morphology of PBX molding powders has changed in varying degrees. There are more surface cracks and the surface morphology are more uneven with the increase of aging time. Moreover， FTIR and XRD results indicate that the molecular structure and crystal form of HNIW/FOX-based PBX have not changed after aging tests. Besides， the analyses of thermal decomposition performance show that the thermal decomposition activation energy of PBX molding powders have decreased after aging tests with the decreases of -5.23%， -5.88%， -7.00% and -8.23%， respectively， which demonstrates that PBX still has good thermal stability after aging tests. The results of mechanical properties show that the compressive strength of HNIW/FOX-7-based PBX increases by 3.18， 3.40， 3.67 MPa and 3.79 MPa， respectively， and the modulus increases by 0.65， 0.79， 0.91 GPa and 0.96 GPa respectively after aging for 7， 14， 21 d and 28 d. Therefore， the change rate of compressive strength and elastic modulus of PBX columns are positively correlated with the aging time， indicating that the compressive strength of PBX columns increases after aging test.

Abstract:In order to analyze the mechanism of shock sensitivity of CL-20/HMX cocrystal close to that of HMX， ReaxFF molecular dynamics simulation was used to investigate the mechanical-thermal structural changes and subsequent initial chemical reactions in CL-20/HMX cocrystals with or without voids. The structural deformation and subsequent chemical reaction process are effectively analyzed by using the momentum mirror model combined with shock-front absorbing boundary condition. When shocks subjected to CL-20， HMX， and CL-20/HMX， it is found that the decomposition speed of CL-20 is faster than that of HMX， while CL-20/HMX"s decomposition speed is very close to HMX"s. Besides， the decomposition speed of CL-20/HMX ［100］ shocks is faster than ［111］ shocks. This phenomenon is related to alternative arrangement of CL-20 and HMX molecular layers and the relative slip amount. When CL-20/HMX with 20 nm diameter void is shocked along the ［100］ direction at particle velocity of 2 km·s^-1， hydrodynamic jet collapse does not occur instead of viscoplastic pore collapse. It largely promotes the rapid decomposition of CL-20 and HMX molecules in the high temperature and high pressure conditions formed by pore collapse and the viscoplastic deformation of crystal structure. A new hot spot formation from the void collapse further enhances the shock loading process.

Abstract:In order to analyze high temperature phase transformation of hexanitrohexaazaisowurtzitane （CL-20）， phase transformation temperatures and coefficients of thermal expansion of ε-， β-， and γ-CL-20 were studied via ReaxFF-lg reactive force field molecular dynamics， with modified valence potential intercept. To validate the applicability of selected force field，the density， cell constant， lattice energy， and sublimation enthalpy for three types of CL-20 at room temperature were calculated. The third order Birch-Murnaghan equation of state was used to fit the p-V curve of ε-CL-20， with pressure ranging from 0 to 280 GPa. And the variation of bulk modulus （B₀） and its partial derivative to pressure （B′₀） with the increase of pressure is analyzed. High temperature phase transformation analysis shows that ε-and γ-CL-20 change phases at 398-423 K， of which the ε→γ phase transition occurs at atmospheric pressure， while the γ→ε phase transition needs 0.5 GPa or higher pressure； β-CL-20 transforms to ε crystal form at 448 K. The thermal expansion coefficient analysis shows that there is no obvious anisotropy in the high temperature thermal expansion process of ε-CL-20， while β- and γ-CL-20 show anisotropy in c direction and b direction， respectively. Results show that the modified ReaxFF-lg reactive force field is suitable for the study of phase transition of ε-， β-， and γ-CL-20 at high temperature and high pressure， while the accuracy of thermal expansion of β- and γ-CL-20 needs to be further improved.

Abstract:A pair of pressed combined CL-20-based and JO-8（HMX-based）explosives are selected to investigate the improvements in the explosion driving performance by using more powerful explosive. This paper presents the test results of detonation velocity， detonation pressure and Gurney coefficient from devices loaded by CL-20-based explosive and JO-8， respectively. Enhanced warhead performance has been demonstrated in static experiments of prefabricated fragment warhead and shaped charge. The results show that the fragment velocity （kinetic energy） driven by CL-20-based explosive is 5.1%-7.3% （10.5%-15.1%） higher than that driven by JO-8. The penetration of shaped charge loaded by CL-20-based explosive is 3.2%-12.6% larger than that loaded by JO-8.

Abstract:Molecular dynamics simulation is an important method to predict the shock sensitivity of energetic materials， yet it is computationally expensive and needs to use force fields that may be unavailable. Here， an algorithm was designed and implemented in a computer program in Python for calculating the Steric Hindrance Index （SHI）， which is a descriptor for evaluating shock sensitivity. The algorithm 1） compresses the crystal unit cell of an energetic material keeping the molecular unit rigid to simulate deformation under shock； 2） establishes a new rectangular coordinate system for the specific slip system and rotates the cell to deal with general shock directions and slip systems； 3） assigns molecular units to layers based on the coordinate of their centroid； 4） calculates the overlapped area of each two adjacent layers after projection along the slip direction； and 5） obtains SHI by normalization of overlapped areas. For PETN， BTF， RDX， and TNT at a compression ratio of 0.1， the calculated average SHI are 0.8707， 0.7940， 0.4228， and 0.0924， respectively， which is consistent with the decreasing order of impact sensitivity mentioned in references. SHI classifies the slip systems in line with those based on molecular dynamics simulations， yet with better computing efficiency and methodological applicability.

Abstract:In order to improve the anti-electromagnetic interference capability of the electronic equipment on blast field， the characteristics of electromagnetic radiation generated by high explosive were studied. An electromagnetic radiation measurement device based on ultra-wideband omnidirectional antenna and shortwave omnidirectional antenna was designed while 8 test points were set up for electromagnetic radiation measurement of 60 kg TNT explosion. The experimental results showthat the electromagnetic radiation signals generated by TNT explosion last up to 600 ms after the explosion， the most intense period of electromagnetic radiation signal produced by TNT explosion is from 80 ms to 110 ms after the explosion. The frequency of the electromagnetic radiation signals generated by the explosion is mainly concentrated below 100 MHz， where the energy distribution in the low frequency band which below 50 MHz is the most obvious. The distance of the center of explosion hasa significant effect on the spectrum distribution of electromagnetic signals， and the frequency distribution of electromagnetic radiation in different directions was inconsistent. The electromagnetic radiation intensity generated by TNT explosion mainly ranges from 64.33 V·m^-1 to 348.25 V·m^-1， and the electromagnetic radiation intensity decreased largely with the increase of detonation distance. The electromagnetic radiation intensity measured by test points in different directions also hasa certain gap， and the difference ranges from 11.1% to 17.7%.

Abstract:In order to study the safety of processing explosives with femtosecond laser， a calculation model of femtsecond laser sequence machining on explosives was established， which took into account the autothermal reaction of the explosives. The processes of femtosecond laser sequence machining on three different explosives （TNT， TATB and HMX） were calculated. The safety of these processes was analyzed. Results show that the frequencies of the femtosecond laser sequence， the heat release of the autothermal reaction and the thermal diffusion coefficient of explosives will affect processing safety. Among these three explosives， the heat release of the autothermal reaction of HMX is the largest， and its thermal diffusion coefficient is the smallest， so its heat accumulation effect is the most significant. Therefore， HMX is ignited when processing with all the three femtosecond sequences with different frequencies （1×10³ Hz， 1×10⁵ Hz and 2×10⁵ Hz）. On the contrary， the heat accumulation effect of TATB is the weakest， so no ignition occurs when processing with the three femtosecond sequence with different frequencies. The heat accumulation effect of TNT is between those of HMX and TATB， so ignition only occurs when using the femtosecond laser sequence with higher frequencies. In the actual machining process， especially for the explosives with greater heat release of the autothermal reaction and smaller thermal diffusion coefficient， femtosecond laser sequence with low frequency should be selected to ensure safety.

Abstract:To gain insights into the stability of nano TATB in different storage environments， aging conditions at 90 ℃， 10%RH， 50%RH， 90%RH and 200 Pa low atmospheric pressure were considered. The microstructure evolution of nano TATB was characterized by small angel neutron scattering （SANS）， scanning electron microscope （SEM）， X-ray diffraction （XRD）， Raman spectroscopy （Raman） and infrared spectroscopy （IR）. Results show that the specific surface area of nano TATB decreases obviously after the thermal aging at 45 ℃， 60 ℃ and 71 ℃， and the higher the aging temperature， the more obvious the specific surface area decreases， accompanied by the growth of some crystal particles. The long-term stability of nano TATB crystal particles is significantly affected by the extreme humidity and heat environment （90 ℃， 90% RH）. After short-term storage （5 days）， the nano TATB particles grow up with the size of about 1-3 μm. The nano TATB particles also grow and form a micro flake structure after aging in a low pressure （200 Pa） environment at 90 ℃. Based on the experiment results， the growth and aging mechanism of nano TATB were discussed. The high surface energy of nano TATB facilitates TATB molecules overcoming the energy barrier， which results in the TATB molecules diffusion and rearrangement on the crystal surface and correspondingly leads to the grow-up of particles.

Abstract:To improve the penetration depth in the target subjected to the jet of reactive materials liner， a shaped charge with Al/Ni-Cu double-layered reactive liners based on the K-charge structure was proposed. The outer and inner liner of the double-layered reactive liner are made of oxygen-free copper and Al/lNi reactive material， respectively. Experimetal study of jet formation， static armor-piercing into steel ingots and the penetration power to typical concrete targets were carried out seperately by using X-ray cinematography. Results show that the double-layered reactive liners with K-charge can form a continuous jet after detonation with obvious pit areas in steel and concrete targets. However， the jet has no obvious reaming effect on penetrating the target. A combined damage effect of kinetic energy and chemical reaction can be achieved by the Al/Ni-Cu double-layered reactive liners. Compared with the Cu-Cu double-layered， less jet accumulated in the target penetrated by the new double-layered reactive linears. Meanwhile， the penetration depth and volume of the steel targets were increased by 20.1% and 23.0%， respectively， while the penetration depth and volume of the concrete targets were increased by 17.2% and 45.6%， respectively.

Abstract:To study the stability of a cast polymer-bonded explosive （PBX） during penetration， projectiles with the PBX-1 charge was launched by a 155mm gun to penetrate concrete targets. The penetration depths at different velocities were obtained， and the critical penetration velocity for maintaining the charge stability was about 490 m·s^-1. Based on the viscoelastic statistical crack （Visco-SCRAM） model， the experiments for testing penetration stability were modelled by a fluid-solid coupling method with large deformation. Thermal-mechanical responses of the charge during penetration were obtained and reasons for the unexpected ignition of the charge were analyzed. The numerical results and experimental data are in a good agreement. The results show that no obvious deformation or damage is observed for the projectile shell， while the cast PBX charge undergoes large deformation and part of charge seeps out from the end gap. During the penetration process， the charge collides with the bottom of charge chamber at high speed and forms a local high-pressure zone. The maximum pressure exceeds 500 MPa when the charge tail is impacted. The tail of the charge is deformed and damaged severely， which may lead to a highly localized temperature and even ignition.

Abstract:With the deepening and development of the concept of long-range operations， long-range strike of missile has become an indispensable part of modern warfare. Therefore， the damage assessment of target hit by missile warhead has been the focus of damage research in recent years. Research of damage assessment in the process of missile warhead striking the target are summarized from four aspects： damage assessment model of target， main subjects in damage process， damage of classified targets， and methods of damage assessment， respectively. Problems such as non-standard judgment of damage degree， unclear relationship of damage mapping and inaccurate solution of damage probability in current stage are pointed out. According to the insufficiency of current study， some suggestions are proposed for the research in the future， which can provide reference for the investigations in the related fields.

Abstract:As the arch structure is one of the common structural forms of underground engineering， the majority of current research focuses on the numerical simulation. The numerical results of structural damage characteristics and response lack corresponding experimental verification， which cannot sufficiently guide the blast resistance design of underground engineering. In order to study the failure mode and blasting resistant performance of underground arch structures with reinforced concrete under explosive load， 5 independent experiments under top explosion had been carried out with different blasting distances and charges. Results show that the damage degree of the arch structure gradually increases with the increase of charge under the same blasting distance. The characteristics of failure mode developed from the concrete cracks at the back surface of blast to the concrete spalling and deformation of steel bars. At last， the concrete collapsed significantly at the center of the vault and the steel bars were severely bent and deformed. The damage of the arch structure under top explosion is not only related to the scaled distance， but also affected by the blasting distance. Under the same scaled distance，the damage degree of arch structure increases significantly with the increase of blasting distance. By analyzing the relationships between the displacement response and the charge mass， the displacement response and the blasting distance， a method is initially proposed for dividing the damage grade based on the deflection-span ratio， which provides experimental support for the structural failure evaluation and analysis in the future.

Abstract:To predict the resistance to penetration of the ultrahigh molecular weight polyethylene laminate（UHMWPEL） accurately， a three-dimensional finite element simulating method of composite structures laminate based on the ABAQUS/Explicit solver platform was developed. A user-defined subroutine VUMAT was proposed to define material behavior by dividing the laminate into two parts with orthotropic lamina and cohesive interface. The lamina and cohesive interface utilized the Hashin criterion and the quadratic stress criterion as the damage initiation criterion separately， while both of them adopted the bilinear constitutive model and the damage evolution method derived from fracture toughness. The residual velocities and damage states of UHMWPEL with thickness of 10 mm and 20 mm penetrated by wedge-shaped steel fragment simulation projectile（FSP） with different initial impact velocities were simulated. The results show that， compared with the existing experiments， the prediction errors of ballistic limits of 10 mm and 20 mm UHMWPEL are 0.6% and 11.3%， respectively， and those of all residual velocities of FSP are less than 14.2%. During the damage and failure process of UHMWPEL， punching failure and local bulging occur in the first stage， followed by large-scale bulging， large-area delamination and fiber tensile failure. This two-stage characterization is similar to that observed in existing experiments， which verifies the reliability of the proposed simulating method.

Abstract:To achieve an effective evaluation of the damage power of all-energetic penetration warhead， a test system for damage power assessment was established based on the 125mm artillery， accompany by a description in multiple physical fields from various aspects such as penetration， reaming， high temperature， high pressure， and arson ignition by arson. Results show that a 16 kg warhead can penetrate a 5-layered steel target at a speed of 952 m·s^-1 to form strong fire which lasts for about 120 ms， with a maximum diffusion range of over 6 m×10 m and a maximum temperature of about 2100 ℃. Compared with the inert warhead， the gains of temperature and overpressure at 1.2 m are about 1270 ℃ and 0.16-0.5MPa， respectively， and the cumulative gain of the broken hole area of 5-layered steel target reaches beyond 300%. Moreover， the warhead has a good arson ignition effect on the fuel tank.

Abstract:In order to improve the ballistic stability of penetrating projectile obliquely penetrating multi-layer concrete target， the structure design of head grooved projectile and pointed oval projectile is proposed. Numerical simulation was carried out based on LS-DYNA software， and two projectiles penetrating 10-layer concrete target were tested. Research shows that in the process of penetrating single-layer concrete thin target， the attitude deflection angle of projectile increases with the increase of initial attack angle， and the attitude deflection of grooved projectile is relatively small compared with that of sharp oval projectile. Compared with the test results of penetrating 10-layer concrete target， grooved projectiles can significantly reduce the deflection attitude of projectiles relative to Ogive-nosed projectiles， which has good ballistic stability and provides reference for the design of projectile with ballistic stability of penetrating multiple targets.

Abstract:To study the jet formation and penetration characteristics of the shaped charge with elliptical cross-section， and the influence of the ratio of long axis to short axis at a fixed short axis， DOP （Depth of Penetration） tests at stand-off 80 mm were carried out for shaped charges with elliptical cross-section. The short axis diameter of elliptical cross-section is 56 mm and the ratio of long axis to short axis are 1， 1.5 and 2， respectively. By using ANSYS/LS-DYNA software to construct related finite element models， the jet formation and penetration process are simulated numerically. The results showed that except for the jet head， the rest of jet was cohesionless at the late stage of stretching. The non-condensed part of jet consists of two fluids with lateral velocity symmetrically distributed over the section of long axis. The non-condensation of jet will significantly reduce the penetration ability of the shaped charge with elliptical cross-section. For the shaped charge with a short axis diameter of 56 mm， the penetration depth decreased by 68.3% from 150 mm to 47.5 mm when the ratio of long axis to short axis changed from 1 to 1.5， while no significant change of penetration ability occurred while the ratio of long axis to short axis changed from 1.5 to 2.

Abstract:To study the initiation process under jet impact and obtain the critical initiation threshold of explosives with different thicknesses， experiments of jet formation with Φ40 mm shaped charge were performed and captured by the high-speed video. The 43-mm thick TNT explosives were covered by 50SiMnVB cover plates with different thicknesses in experiments. The critical initiation threshold， the response under different stimulus intensities and the expansion velocity of reaction products were obtained. The numerical simulation of finite-thickness explosive under jet impact was carried out by using numerical simulation software. The propagation process of bow wave in explosive under jet impact and the relationship between critical initiation threshold and the thickness of finite-thickness explosive were analysed. The simulation results were compared and verified by the experimental data. The results show that the critical initiation threshold of TNT with a thickness of 43 mm is 37 mm³·μs^-2， and the expansion rate of reaction products varies by at least one order of magnitude between different responses. When the jet impacts on a finite-thickness explosive， a certain distance is required for a bow shock wave evolving into a detonation wave. The higher the tip velocity of the residual jet is， the shorter the distance is required for the evolution of bow shock wave to detonation wave. Therefore， the decrease of explosive thickness will lead to the increase of critical initiation threshold of finite-thickness explosive， and the logarithm of critical initiation threshold is approximately linear with the logarithm of explosive thickness.

Abstract:To investigate the shock initiation characteristics of the insensitive aluminized melt-cast explosives， a one-dimensional Lagrangian test system was established with the manganin piezoresistive pressure gauges and the loading technique of chemical explosion. The shock initiation process of an aluminized DNAN-based melt-cast explosive was measured， and the growth histories of pressure were obtained under different loading pressures. By virtue of the mesoscopic model of reaction rate of the aluminized melt-cast Duan-Zhang-Kim （DZK） ， the parameters of the aluminized explosive were determined and then the shock initiation process was simulated numerically. It is found that the higher the loading pressure is， the faster the detonation grows inside the aluminized explosive. In the shock initiation of the aluminized melt-cast explosive， the reaction degree and reaction rate are low near the leading wave front. However， the reaction rate of explosive after wave increases continuously and reaches the peak value in a while with the ignition reaction and the accumulation of chemical reaction Furthermore， compared with the growth history of particle velocity， those of pressure involve more detail of the growth of reaction rate， which are more suitable to be used in validating the reaction rate models and determining the parameters of reaction flow models.

Abstract:As the diffusion and migration of the deterrents affect the service life of gun propellants during the storage period， the molecular dynamics simulation （MD simulation） was applied to compare the diffusion rate of the small molecule dibutyl phthalate （DBP） and polyneopentyl glycol adipate （NA） in gun propellants. Meanwhile， the effect of nitroglycerin （NG） content on the diffusion of DBP and NA in double base gun propellants was explored and the diffusion mechanism was analyzed. The results indicate that the diffusivity of DBP and NA in nitrocellulose （NC） is equivalent at 5 ℃ and the diffusion coefficients are both in the order of 10^-12 m²∙s^-1. The diffusion coefficients of DBP and NA are 1.88×10^-11 m²∙s^-1 and 7.57×10^-12 m²∙s^-1 at 65 ℃， respectively. The diffusion coefficients of DBP and NA are 3.42×10^-11 m²∙s^-1 and 1.11×10^-11 m²∙s^-1 at 85 ℃， respectively. At the same temperature， the order of the diffusion coefficient of the deterrents is DBP>NA， which shows that NA has better anti-migration properties， which are more prominent at high temperatures. Owing to the high temperature， the peak value reduces， thus weakening interaction between DBP， NA and NC， meanwhile， the fractional free volume of system increases， which is conducive to the diffusion of DBP and NA. The diffusion capacity of DBP and NA increases with the increase of NG content. Adding NG weakens the interaction between DBP， NA and NC， so DBP and NA move more actively and the diffusion ability increases. The molecular dynamics simulation method is used to study the diffusion properties of the deterrents in gun propellants， which provides important theoretical guidance for predicting the life of gun propellants.

Abstract:The thermal stress fracture of polymer bonded explosive （PBX） was studied by a combined simulated and experimental method using notched PBX cylinders. A 2D axisymmetric finite element model， which contained temperature related material properties， was employed to calculate the thermal elastic-plastic response of PBX cylinders under the condition of the initial cooling temperature of 50 ℃ and cooling rate of 10 ℃·min^-1. Temperature， strain and acoustic emission （AE） measurements were used in an air-cooling test for verification. Simulation results show that there is a temperature boundary layer near the surface and a temperature difference in the cylinder， resulting in tension stress greater than the strength of the PBX. A circular notch in the cylindrical surface distinctly amplifies the thermal stress and the stress gradient. The factor of stress concentration reaches a maximum of 1.6 when the notch radius is 2 mm. The PBX endures brittle broken during thermal shock when thermal stress exceeded its tension strength， accompanied with strong AE signals and a sharply decline on strain-time response. The critical fracture temperature of cylinders with and without a notch determined by simulation are respectively 8.3 ℃ and 12.6 ℃， while the value determined by experiment are respectively 9.2 ℃ and 12.5 ℃.

Abstract:In order to explore the influence of the complexity of crack distribution and shape on the particularity of ultrasonic propagation in curved surface components of polymer bonded explosives （PBX）， and optimize the parameters of ultrasonic oblique incidence testing， a numerical model of ultrasonic nondestructive testing of curved PBX components was established， based on the finite element method and typical testing conditions. The surface P under the excitation of transient displacement was calculated and analyzed by COMSOL commercial software. The propagation law of the internal sound field of PBX component was simulated， the ultrasonic detection signals of different angles and cracks were calculated， and the influence of the incident angle and other parameters on the detection results of small angle oblique incidence of ultrasonic water immersion crack of curved PBX component was studied. The numerical simulation results show that when the angle between the beam and the crack is 8°~10°， the small angle oblique incidence ultrasonic detection method has the best detection performance for PBX internal crack defects， and is not affected by the crack depth. At the same time， the curved PBX simulation specimen was designed and manufactured， the small angle ultrasonic testing experiment system was built， and the ultrasonic testing experiments under different incident angles and crack parameters were carried out. The optimal testing angle （8°） obtained from the experiment was consistent with the simulation results （8°~10°）， which verified the rationality of the numerical simulation results and the effectiveness of small angle ultrasonic testing.

Abstract:The dynamic characteristics of unreacted solid explosive PBX-59 under ramp wave compression were studied with a magnetic driven loading experimental technique， and the dynamic response of PBX-59 under a peak pressure up to 18.5 GPa was obtained. The p-V relationship， the acoustic velocity-particle velocity relationship and other dynamic parameters of PBX-59 were obtained by the iterative Lagrange data processing method modified by impedance matching under the ramp wave compression. Combined with the dyamic parameters and isentropic equation of state derived from experimental data， the experimental results were hydrodynamically simulated. The numerical calculation agree well with the experimental results， which verifies the validity of the experimental technology， data processing method， and physical model.

Abstract:To characterize the structure of TATB-based polymer bonded explosives（PBX） on the meso-scale， an automatic granule boundary extraction method based on the two-dimensional（2D） reconstructed CT images with low quality is presented. Binarization was first performed according to the gray level distribution of the original CT images of TATB-based PBX. Then a proposed elastic capsule algorithm was applied to the binary images and an approximate location of the granule boundary was obtained. With a combination of morphological operations and the marker-based watershed algorithm， a more accurate segmentation of TATB-based PBX granules was realized. The present granule boundary extraction method for 2D CT images of TATB-based PBX shows improved accuracy and portability， as compared to Canny algorithm， iterative phase congruency， SLIC superpixels and other feature extraction techniques.