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Abstract:The equation of state and vibration properties of TATB crystal were investigated by using the density functional theory (DFT) and combining with van der Walls force correction(vdW-DF2). The partial vibration modes of TATB crystal were reassigned. Vibration mode coupling and the intermolecular interaction process were studied under pressure process up 8.5 GPa. Results show that the NO₂ and NH₂ vibrations were strongly coupled in TATB crystal. The vibration in the wave number range of 1100 cm^-1 to 1500 cm^-1 is particularly complex because of the coupling of NH₂ with NO₂ and benzene ring vibrations. With increasing pressure, TATB molecules from neighboring layers bend and close to each other, causing a coupling of NH₂ plane twist vibration or wag with NO₂ shear vibration, indicating a strengthening of intermolecular hydrogen bonding.

Abstract:To study the influence of the electric field produced in the electric ignition process of hydroxylamine nitrate base propellant on the propellant, the geometric configuration of hydroxylamine nitrate was optimized by the B3LYP/6-311++G (d, p) method. The nature of the hydrogen bonding interaction was revealed by the analysis of the natural bond orbital. The theoretical study of H atom transfer in the process of configuration formation was performed. Under the external electric fields ranging from -0.005 a.u. to 0.005 a.u., the configurations of transition states and activation barrier of H atom transfer were calculated. The change in bond length, binding energy and bond level distribution of hydrogen bonding interaction with the electric field were calculated Results show that with the enhancement of positive electric field, the activation barrier of H atom transfer decreases gradually, it is conducive to the formation of the hydroxylamine nitrate configuration. The bond length of hydrogen bonding interaction of hydroxylamine nitrate shortens, the strength of the bond enhances. The binding energy of hydroxylamine nitrate increases, the stability of hydroxylamine nitrate enhances. The electric field effect in the ignition process has a negative impact on the polarization or ionization of hydroxylamine nitrate, which is not conducive to the ignition of the propellant.

Abstract:Molecular dynamics simulations were performed to explore structural arrangements of nitromethane (NM) on the graphene (GRA) surface. The simulation results show that ordered and layered structural arrangements of NM are induced by the GRA surface. In the nearest layer to the GRA surface, the structural ordering is highest. The preferred orientation of NM is found, i.e. the dipole vector is parallel with the GRA surface, leading to more concentrated and higher density than bulk NM. To maximize the interactions between NM and GRA, furthermore, some NM molecules change from eclipsed structure to staggered structure. The influence of GRA on structural arrangements of NM is weakened as the distance between NM and GRA surface increases. The structural arrangements of NM trends toward disordered state of bulk NM started with the third layer.

Abstract:To obtain the prediction model with higher precision and larger suitable scope for predicting impact sensitivity of polynitro compounds, based on the quantitative structure-property relationship (QSPR) principle, genetic algorithm (GA) was adopted in variable selection and GA-multiple linear regression (MLR) model and GA-artificial neural networks(ANN) model were established and employed in research for figuring out the relationship between impact sensitivity and molecular structure of 149 kinds of polynitro compounds. Two model′s correlation coefficient is 0.854 and 0.974, respectively, the root-mean-square error is 0.195 and 0.071, respectively and the mean-absolute-error is 0.157 and 0.051, respectively. By comparing the models, the results show that the prediction precision of two models are higher than the existing QSPR model, and GA-ANN model is obviously superior to GA-MLR model.

Abstract:A mesoscopic mechanics model of random distribution of explosive particles was constructed by applying circular approximation. The numerical simulation of mechanical behaviors in a pressing process of HMX based polymer bonded explosive (PBX) based on the material point method was carried out. The change in stress and temperature of the system and the deformation of explosive particles during the pressing process were emphatically examined. Simulation results show that the compression process can be divided into two stages: integration stage and consolidation stage. In the integration step, the explosive particles are subjected to pressure and rearrangement. The stress is produced at the contact part between explosive particles and compression surface, forming several stress trains and then the stress trains is propagated along the contact surface between explosive particles upward and downward. Temperature in the system gradually increases in the stress process. The maximum temperature rise in the locality of the system is 10 K. In the consolidation step, after the plastic deformation process of the system, the internal stress gradient decreases, at the same time, obvious temperature difference in the system is existed, the maximum temperature difference is 20 K.

Abstract:To research the influence of injection structure on gas-curtain generated by underwater launched gun, the three-dimensional unsteady mathematical model of multi gas jets in liquid tube was established, and the distribution of phase, pressure and velocity were numerical acquired. Numerical result indicates that after the injection of multi gas jets, Taylor cavities are formed in the liquid Tube. With the mixing process between the Taylor cavities and liquid medium, the multi gas jets merges and the gas-curtain is generated. During the merging process, the pressure in the flow field fluctuates and low-velocity vortex areas are formed on the gas-liquid interface. When the diameter of the slant nozzles increases from 1.5 mm to 2 mm, the reflux of the oblique jets is enhanced, which can result in the improvement of axial expansion performance of the side jets, and the drainage performance of gas-curtain is strengthened, the velocity of the liquid above the gas-curtain increases from 8.26 m·s^-1 to 9.4 m·s^-1 at 8 ms.

Abstract:Two nitrate ester energetic materials 1, 4-dihydroxy-2, 5-dinitrato-3, 6-dinitrocyclohexane (2) and 1, 2, 4, 5-tetranitrato-3, 6-dinitrocyclohexane (3) were synthesized from glyoxal and nitromethane by the process of condensation and nitration with total yields of 7.79% and 7.52%, and the structures were characterized by IR, NMR, and elemental analysis. The single crystal of compound 2 was obtained. Thermal and detonation properties of compound 2 and 3 were studied with TG-DTG, DSC and B3LYB method. Results show that the crystal of compound 2 belongs to the monoclinic system with space group of P2₁/n. The thermal decomposition peak temperatures of compound 2 and 3 are 241.1 ℃ and 192.0 ℃. The detonation velocity and detonation pressure of compound 2 and 3 were 9079 m·s^-1, 37.75 GPa and 9616 m·s^-1, 43.26 GPa, respectively.

Abstract:The cooling crystallization kinetics of 3, 4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in V(acetic acid):V(water)=7:3 mixed solvent was investigated by a batch crystallizer. Based on the equation of population balance, the nucleation and growth rate equation of DNTF cooling crystallization were determined performing multiple linear regression of experimental data by the least squares method. Results show that the indexes of crystal growth rate and nucleation rate of crystal for supersaturated degree are 3.83 and 1.3, respectively, meaning that the nucleation and growth rates of crystal increase with increasing the supersaturated degree of the system, but the growth rate increases faster. The index of crystal nucleation rate for the suspension particle density is up to 2.14, it means that with increasing the suspension particle density, the crystal nucleation rate increases significantly but the growth rate does not change, which are not favorable to crystal growth.

Abstract:To investigate the long-term storage aging damage and mechanical environment adaptability of ammunition charge, the macroscopic structure defects of the pressed HMX-based polymer bonded explosive(PBX) charge stored for 4, 8 and 12 years were observed by computerized tomography(CT scanning). The micro damage of the charge stored for 4 and 12 years was analyzed by scanning electron microscope(SEM). The mechanical environment adaptability of the charge stored for 12 years was examined by impact and vibration tests. Results indicate that the defects of PBX charge occur after long-term storage. The defects are expressed as relatively straight cracks penetrated along the radial direction and circumferential uniform distribution. The crack number increases with the increase of storage period. The micro damage model of charge defects is the interface debonding and matrix cracking. After certain loading subjected to impact and vibration, the 2 charge cracks are increased, but PBX charge ammunition with defect can ensure to be safe.

Abstract:In order to obtain a narrow distribution, spherical, smaller size, sub-micron particles RDX, a nozzle for solution enhanced dispersion by supercritical fluids(SEDS) technology has been designed. Based on the principle of gas atomization, the ring slit structure and the microporous turbulent zone were used, so that CO₂ fluid flowed in the nozzle in high speed, the problems of block, too large size particles issues have been solved. Research shows that under the same experimental conditions, temperature is 35 ℃, pressure is 10 MPa, CO₂ flow rate is 15 kg·h^-1, RDX solution flow rate is 2 mL·min^-1, when the original internal mixing nozzle of SFP2 instrument is used, RDX particles of the distribution range from 3 μm to 15 μm are collected, the process of preparation is easy to jam. However, when the novel structure nozzle is used, sub-micron RDX particles are collected, which has a distribution range from 0.1 μm to 2 μm, and the average particle diameter is 660 nm. Both the inner diameter and the wall thickness of center hole are 0.1 mm, ring slit width is 0.1 mm, turbulent zone length to diameter ratio is 10:1, pressure difference is 1 MPa. The problem of jam in the preparation process is resolved perfectly by the novel nozzle.

Abstract:A selective and sensitive high performance liquid chromatography(HPLC) was optimized for quantitative analysis of pentaerythritol tetranitrate(PETN) based polymer bonder explosive (PBX) with conditions of SB-C18 column(4.5 mm×250 mm, 5 μm), UV detector, mobile phase V(acetonitrile):V(water)=70:30, flow rate of 1.0 mL·min^-1 and detection wavelength 225 nm. The influences of sample treat method, sample mass and solvent were studied. Results show that the relative standard deviation of reproducibility is 0.13% when PBX sample is cutted to granule (volume 1.0 mm³, mass 200 mg) in 100 mL flask and ultrarsonic dissolved 30 min by acetonitrile and then stands for 16 h. T he detection limit for PETN is 0.054 μg·mL^-1 and there is a good linear between the peak areas and the mass concentration of 0.8-2.0 mg·mL^-1 with linear correlation coefficients of 0.9994.

Abstract:To analyze the expansion characteristics of pulsed plasma jet in air, the expansion process of pulsed plasma jet generated by a plasma generator was studied by a piezoelectric pressure sensor and a digital high-speed video system. The relation of change in the extended volume, axial displacement and radial displacement of pulsed plasma jet in atmosphere with time under different discharge voltage and jet breaking pressure was treated and obtained by Photoshop software. Results show that when the pulsed plasma jet is expanded, its shape is gradually extended from the initial shape like ellipsoid to a conical head and an elongated cylindrical tail. The axial displacement of the jet is always larger than the radial displacement. Extended volume reveals a single peak distribution with time. Increasing the discharge voltage and jet breaking pressure can improve the expansion ability of the jet, and the larger the discharge voltage, the more violent the turbulent mixing in the plasma jet expansion.

Abstract:To evaluate the reliability of laser diode initiation(LDI) subsystem at low temperature, the performances of a dual-way LDI subsystem and its individual parts were studied by temperature test and initiation test. Based on sensitivity tests of laser initiators, 99.9% firing laser energy at 95% confidence level was estimated as 0.783 mJ at 20 ℃ and 0.747 mJ at -40 ℃. The characteristics of semiconductor laser and optical transmission efficiencies were studied at -40-20 ℃ and a numerical fitting empirical formula was obtained via analysis. The value of firing energy to each laser initiator was calculated and obtained using the fitting formula and the ignition margin of the LDI subsystem obtained is more than 3. Through low temperature firing test, it is verified that the dual-way LDI subsystem can be normally fired, having a higher design margin.

Abstract:The TNT red water in the process of TNT production was pretreated by the complex extraction using trinoctylamine as a complex extraction agent. Seeing the removal rate of chemical oxygen demand (COD) and recycle use of extraction agent as goal, the effect of pH value, stirring speed, stirring time and the ratio of extraction agent and wastewater on the extraction efficiency was investigated. A study of intermittent experiment and continuous experiment was carried out. Results show that the extraction efficiency is the best when pH value is 0.9, stirring speed is 220 r·min^-1, stirring time is 30 min. When the volume radio of the extraction agent and wastewater is 2.4, the COD removal rate of common TNT red water reaches 99.4% by realizing the control of content of COD in effluent water via changing the extraction phase ratio. The COD removal rate of military TNT red water reaches 99.0%. When the volume ratio of extraction agent and wastewater is 2.3-2.4, the extraction agent can be recycled.

Abstract:In the process of explosive machining, wastewater containing pollutants such as explosives and oily coolant was produced. Ceramic ultra-filtration membranes could be used to remove the suspended solids for the reuse of explosive wastewater. The effects of operation parameters on permeate flux and turbidity were investigated. The membrane fouling was investigated by concentration and washing experiments. Moreover, the water quality analysis and explosive column immersing experiments were proposed to investigate the feasibility for reuse of wastewater. Results indicate that the feed pressure, circular flux, and retained flux mainly affect the permeate flux instead of turbidity. The permeate flux decreases by 40% after 10 times of concentration experiments. The tap water and 1.5% NaOH solution were used for physical and chemical membrane washing and the permeate flux recovered 96.6% after chemical washing. The permeate water of membrane and the cooling water of machine tool are similar on indicators pH, oil concentration, turbidity, and suspended solids. Moreover, the effects of permeate water and cooling water on the color of the surface of TNT and HMX explosive column are consistent. Therefore, the ceramic ultra-filtration membrane technology could be used for the reuse of wastewater in explosive machining process.

Abstract:The correlative definition of energetic materials component and its geometrical parameters measurement techniques were summarized. The current research on measuring technology with mechanical device, coordinate measuring techniques, portable coordinate measuring techniques and 3D optical no-touching measurement techniques for the energetic materials component at home and abroad were summarized. Furthermore, the advantages and disadvantages of each techniques were analyzed. Application assumption of 3D optical no-touching measurement techniques on the energetic materials component were put forward. Finally, the development direction of geometrical parameters measurement techniques on different size and precision for energetic materials component was pointed out.

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