CHINESE JOURNAL OF ENERGETIC MATERIALS
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  • Multi-scale Damage Evolution Analysis of HTPB Propellant Based on In-situ Stretching
    CJEM | 2024 No.2
  • Stabilization Coating of Aluminum-Lithium Alloy and its Application in Propellant
    CJEM | 2024 No.1
  • Preparation and Properties of Millimeter-sized Hollow Spheres for CL-20/HMX Co-crystal by Droplet Confined Crystallization
    CJEM | 2023 No.12
  • Preparation of DAAF/Fluororubber Composite Microspheres by Droplet Microfluidic Technology
    CJEM | 2023 No.11
  • Influence of Initial Free Cavity Volume on the Reaction Violence of PBX-3 in Slow Cook-off
    CJEM | 2023 No.10
  • Preparation and Reactivity Properties of Embedded-Coated AlH3 Energetic Composite Particles
    CJEM | 2023 No.9
  • Experimental and Numerical Simulation of Shaped Charge Jet Penetrating Concrete and Rock Targets
    CJEM | 2023 No.8
  • Preparation and Ignition Performance of Super Thermite with Highly Spherical Core-shell Structure
    CJEM | 2023 No.7
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    • YU Tian-hao, YAN Ya-bin, WANG Xiao-yuan

      Online:February 07, 2024  DOI: 10.11943/CJEM2023239

      Abstract:As one of the mechanically vulnerable components in the structure of solid rocket motors, it is extremely important to clarify the physical and chemical properties of the interface for solid propellants, damage evolution patterns, and the effect of dewetting on the integrity of the propellant grain structure. Compared with experiments,, numerical simulation can quickly and efficiently study the different physicochemical properties of various interface systems, and has good application prospects. From the microscale molecular dynamics that can reveal the mechanism of experimental phenomena from a molecular perspective, the mesoscale finite element numerical simulation considering the microstructure of complex filler particles and other materials in solid propellants, and the macroscopic numerical simulation closely related to the macroscopic mechanical response, the research progress of various interface mechanical properties for composite solid propellants was reviewed, the driving effect of numerical simulation for composite solid propellant interfaces at multiple scales on solid propellant engineering design at multiple scales and the current shortcomings were discussed, and the future development directions were also put forward.

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    • XUE Hui-hui, HUANG Juan, ZHANG A-lei, CHEN Ke-quan, ZHOU Jie, DING Ya-jun, XIAO Zhong-liang

      Online:February 03, 2024  DOI: 10.11943/CJEM2023203

      Abstract:A green non-toxic, easy and accuracy analysis method of the nitrogen content in nitrocellulose (NC) was investigated by using ultraviolet spectrophotometer, which was based on a linear relationship between the nitrogen content of NC and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Under the same reaction condition, five NC standard samlpes with known nitrogen contents were hydrolyzed. The concentrations of NO2- and NO3- in the hydrolysate were measured by the ultraviolet spectrophotometer, and the reaction condition of measuring system was optimized. The linear relationship between the nitrogen content of NC standards (x) and the molar ratio of nitrite-to-nitrate ions (y) was determined by the least squares method. Finally, three NC samples were used to evaluate the proposed method. Results show that the concentration of NO2- and NO3- in alkaline hydrolysate can be measured simultaneously by ultraviolet spectrophotometer, and the most suitable reaction condition is as follows: the concentration of sulfamic acid of 20 g·L-1, and the process time of 30 min. Under the optimal reaction condition, the linear relationship between x and y is obtained, and the R2 is 0.9893. The verification results of NCA, NCB and NCC reveal that the nitrogen content determined by ultraviolet spectrophotometer and actual nitrogen contents are in good agreement. The relative standard deviation (n=4) values are all less than 0.150%.

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    • YAO Chao-qun, LIU Xuan, ZHANG De-wang, ZHAO Shuai-nan, GUO Xiao-ni, CHEN Guang-wen

      Online:February 01, 2024  DOI: 10.11943/CJEM2024017

      Abstract:Energetic materials are widely applied in the area of weaponry industry, aerospace and civil construction. The synthesis of energetic materials is very complex and of great danger in the conventional stirred tank, which can no longer fulfill the requirement of product quality and process safety. The microreaction technology, which has significant advantages of fast heat/mass transfer and excellent safety, has great potential in the synthesis of energetic materials. This review introduces the progress from four aspects, namely the principle of microreaction technology, energetic compound synthesis, production of energetic particles and ultrasonic microreactors. It aims to elaborate the application characteristics of microreaction technology in the area of energetic materials based on the viewpoint of chemical engineering. Finally, the challenges and future direction are summarized and outlooked, including reaction kinetics/thermal kinetics, mixing intensification of viscous and solid‐involved fluids, reaction scale‐up and intelligent system, waste treatment and how to embrace emerging technologies such as artificial intelligence.

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    • LI Jia-wei, LI Jia-fei, ZHANG Dong-xu, XUE Zhi-hua, LI Zhe-qiang, LEI Jin-shan, WANG Jing-yu, WU Bi-dong

      Online:January 30, 2024  DOI: 10.11943/CJEM2023264

      Abstract:To improve the safety of the charging process of molecular perovskite energetic material (DAP-4), spherical granulation of DAP-4-based energetic composite microspheres was realized by altering the composite ratio of the bonding agents, Glycidyl Azide Polymer (GAP) and nitrocellulose (NC) (constituting 2% of the mass of DAP-4) using the coaxial droplet microfluidic technology. The macro and micro morphology, crystal structure, thermal properties, combustion properties, and mechanical sensitivity of the samples were tested and analyzed by scanning electron microscope, X-ray diffractometer, differential thermal scanning calorimeter, thermogravimetric analyzer, high-speed photography, impact sensitivity tester and friction sensitivity tester. The results indicate that DAP-4 has the best sphericity when the ratio of GAP to NC is 4∶1. The crystal structure of DAP-4 is not changed after spheroidizing granulation, and the peak temperature of thermal decomposition is slightly advanced. The combustion time of DAP-4 microspheres is slightly longer than that of raw materials, and the overall performance is still very stable and continuous combustion, retaining its excellent combustion performance. The GN41 microspheres can significantly improve fluidity while reducing mechanical sensitivity and improve the safety of the charging process.

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    • YANG Ya-lin, QIN Yi-feng, XIA Jiang-lu, DU Hui-ying, LI Xin-yu, WU Bo, MA Cong-ming

      Online:January 30, 2024  DOI: 10.11943/CJEM2024006

      Abstract:Polycyclic energetic compounds with high nitrogen content have attracted much attention owing to their distinctive advantages in constructing novel energetic molecules with low mechanical sensitivity, good thermal stability and high density. The construction of polycyclic skeletons involves the incorporation of tetrazole into fused heterocycle, serving as high-energy organic fuel and hydrogen bond donors. Three self-assembled non-hydrated energetic compounds, namely 7-amino-6-(2H-tetrazol-5-yl)-pyrazolo[1,5-a]pyrimidine (1), 7-diamino-6-(2H-tetrazol-5-yl)-[1,2,4]triazolo[1,5-a]pyrimidine perchlorate (2), and 2,7-diamino-6-(2H-tetrazol-5-yl)-[1,2,4]triazolo[1,5-a]pyrimidine perchlorate (3), were synthesized through noncovalent self-assembly of polycyclic skeleton with the oxidizing structural unit HClO4 rich in hydrogen bond acceptors. The structural characterization employed Nuclear Magnetic Resonance Spectroscopy and single crystal X-ray diffraction, while thermal behaviors and mechanical sensitivities were determined by differential scanning calorimetry-thermogravimetry and BAM methods. Detonation performances were predicted utilizing the Gaussian 09 program and EXPLO5 V6.05.02. The results show that three compounds exhibit high crystal densities (ρ: 1.75-1.86 g·cm-3), good thermal stabilities (decomposition temperature (onset): 184-260 ℃), and good detonation performances (detonation velocity: 7343-7570 m·s-1; detonation pressure: 21.1~22.8 GPa), surpassing those of traditional explosives trinitrotoluene (TNT). Both compound 1 (impact sensitivity (IS) > 40 J, friction sensitivity (FS)=216 N) and compound 3IS=25 J, FS = 240 N) exhibit low mechanical sensitivity.

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    • WEN Yi-meng, MAO Jun-qing, MA Song-yu-chen, DI Yang, LIU Tao, LIU Jie

      Online:January 25, 2024  DOI: 10.11943/CJEM2023200

      Abstract:Due to contacts with additives or changes of environmental conditions (temperature or pressure), the polymorphism hexanitrohexaazaisowurtzitane (CL-20) is easy to transform into mixed crystal form in propellant system, which leads to structural damage and performance degradation of the propellant. In order to hinder the contact between the solvent and CL-20, then inhibit the crystal transformation of CL-20, the polyphenol amine (PCHA) film was prepared based on the oxidative self-polymerization of hexamethylenediamine (HMDA) and catechol (CCh). The surface of CL-20 crystal was modified by water suspension method under mild conditions. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RAMAN), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to study the morphology, coating content, thermal properties, and stability in ethylene glycol solution for the composite particles. The results show that HMDA and CCh can modify the surface of CL-20 crystal under mild conditions and form a dense PCHA coating layer. The content of PCHA is about 1% measured by dissolution weighing method and high performance liquid chromatography (HPLC). The PCHA coating layer increases the crystal transition and thermal decomposition temperature by 16 ℃ and 7 ℃, respectively. The thermal decomposition activation energy Ea at different heating rates was calculated by Kissinger method. The activation energy of CL-20@PCHA is about 8 kJ·mol-1 higher than that of CL-20, and the thermal stability is greatly improved. The XRD test results indicate that the PCHA film can effectively prevent the contact between the solvent and CL-20, slow down the dissolution rate of CL-20 in the solvent, and effectively inhibit the crystal transformation of CL-20.

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    • XIA Wen-tao, DU Fang, LI Yi-heng, LIN Li-yun, QU Wei-chen, QIN Rui, TAO Bo-wen, GU Jian

      Online:January 24, 2024  DOI: 10.11943/CJEM2023230

      Abstract:In order to investigate the combustion characteristics of Al powders in NOx, the reaction mechanism of Al with three nitrogen oxides (NO2, NO and N2O) was studied by means of density functional theory ωB97X. Firstly, the geometries of reactants, intermediates, transition states and products were optimized with all parameters. The authenticity of intermediates and transition states was confirmed by frequency analysis. The transition states were further determined by intrinsic reaction coordinates (IRC) calculation, and then the detailed reaction paths and mechanisms were obtained. High precision single-point energy of each structure was obtained by using the double hybrid functional PWPB95 combined with DFT-D3 correction and def2-TZVPP basis set. The rate constants of the related reactions were calculated by using the variational interpolation transition state theory, and the Arrhenius expressions for each reaction are obtained. The results show that the reaction process of Al with NO and NO2 is that Al and O atoms join together to form the intermediate of the complex, and then break the N─O bond through the ternary ring transition state to form the product. When Al reacts with N2O, Al reacts with N atoms to form a complex and then the elimination reaction takes place through the ring transition states. The activation energies of the reaction of Al with NO2, NO and N2O are 4.3 kJ·mol-1,249 kJ·mol-1 and 13.4 kJ·mol-1, respectively. From 2400 K to 4100 K, the reaction rate of Al with NO2 and N2O is higher than 106 m3·mol-1·s-1, which indicates that the reaction is easy to take place and the reaction rate is very fast, and the reaction rate of Al with NO is about 1/10000 of that of Al with NO2 and N2O.

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    • LIU Xuan, YAO Chao-qun, LIAN Ying-jiang, HAN Mei, CHEN Guang-wen

      Online:January 22, 2024  DOI: 10.11943/CJEM2023256

      Abstract:The study investigated the nitration of 2-methyl-4,6-pyrimidinone (MPO) with nitrate sulfur mixed acid in a microchannel reactor, and further prepared 1,1-diamino-2,2-dinitroethylene (FOX-7) through hydrolysis reaction. N-octane was introduced as an inert solvent to generate slug flow for the reaction system. The reaction occurred inside disperse droplets, thus solving the problem of clogging of nitration intermediates in the microchannel reactor and achieving process intensification and continuous operation. The effects of reaction temperature, residence time, material ratio, and hydrolysis conditions on the product yield were investigated. The combination of microreactor and stirred reactor was proposed. At the molar ratio of nitric acid to MPO of 4.4, reaction temperature of 30 ℃, and residence time of 3 min in the microreactor followed by a 30 min insulation reaction in a stirred kettle, and the ring-opening realized by the hydrolysis with ice water for 2 h, the yield of FOX-7 could reach 90.1%, with a purity of over 99%.

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    • PAN Chang-xin, LIU Feng, BI Ru-jie, DAI Wei, ZHU Zheng-de, CHENG Yu-hang

      Online:January 17, 2024  DOI: 10.11943/CJEM2023219

      Abstract:In order to study the effect of high pressure from screw pumping and medium deep hole charging on the microstructure and thermal stability of the on-site mixed emulsion explosive matrix, the microstructure, particle size distribution, crystallization content, thermal decomposition process, thermal decomposition reaction activation energy, thermal decomposition mechanism function and rate equation of the matrix under atmospheric and high pressures were studied by optical microscope, laser particle size analyzer, water solubility experiment, thermogravimetry and derivative thermogravimetry (TG-DTG) couple method, Kissinger method and Ozawa method, Coats-Redfern method and ?atava method. The results show that from atmospheric pressure to high pressure, polymerization, demulsification and crystallization of the intra-matrix phase droplets appeared, the particle size increased from 3.717 μm to 4.474 μm, the precipitation amount of ammonium nitrate crystals increased from 0.0530 g to 0.0640 g, and the uniformity of the emulsion system was weakened. The average thermal decomposition onset temperature of the matrix Tonset increased from 157.4 ℃ to 184.0 ℃, the average first-order derivative thermogravimetric peak temperature Tp increased from 262.6 ℃ to 281.8 ℃, the average mass loss rate increased from 0.1454 %·s-1 to 0.1476 %·s-1, and the reaction activation energy decreased from 108.49 kJ·mol-1 to 84.74 kJ·mol-1. The free water released by evaporative demulsification under high pressure might cause the rise of Tonset and Tp, and the thermal decomposition reaction was more likely to occur. The activation energy calculated by the Ozawa method had a different trend with the increase of conversion rate, and the thermal decomposition reaction mechanism function changed from Valensi equation to inverse Jinder equation and the rate equation also changed. The high pressure promotes the process of droplet polymerization, demulsification and crystallization of the intra-matrix phase, reduces the activation energy of the thermal decomposition reaction, and weakens the homogeneity and thermal stability of the system.

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    • LI Si-han, WANG Ke-jian, NIU Yu-lei, HUANG Han-zhe, MA Zi-yu

      Online:January 11, 2024  DOI: 10.11943/CJEM2023209

      Abstract:In order to study the quasi-static compression behavior of polymer bonded explosive (PBX), the uniaxial quasi-static compression tests were carried out on two typical PBX substitute materials (with and without aluminum powder) at different strain rates, and their mechanical properties were compared and analyzed. Based on the Zu-Wang-Tang (ZWT) model, a new model was proposed to describe the quasi-static compression behavior of materials. The constitutive model parameters were obtained by genetic algorithm, and the model was developed by using Fortran language in the User Material (UMAT) subroutine interface of Abaqus finite element analysis software. Results show that the quasi-static compression process of casting PBX substitute materials can be divided into three stages: elastic compression, stress decay and instability failure. The mechanical behavior of quasi-static compression is obviously correlated with the strain rate. With the increase of the strain rate, the effective compressive strain of the material is basically unchanged, while the logarithms of compression modulus, yield strength and compressive strength are linearly related to the logarithm of strain rate. The addition of aluminum powder can improve the compression modulus, yield strength and compression strength of casting PBX substitute materials. The newly constructed constitutive model can better describe the quasi-static compression behavior of casted PBX substitute materials, and its universality is validated by the finite element analysis software. The coefficients of determination (R2) between the simulated and experimental results are higher than 0.98, indicating a high level of consistency.

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    • LIU Rui, LIU Jian, TANG Yue-chuan, ZHANG Chao-yang, HUANG Jing, HUANG xin

      Online:January 08, 2024  DOI: 10.11943/CJEM2023226

      Abstract:The explore of energetic molecules faces multiple challenges, and the traditional design method are inefficient. The emergence of computer-aided molecular design has changed the research and development model. This review provides an overview of the development of energetic molecular design and introduces the current research status of computer-aided energetic molecular design. By summarizing the latest advancements in Artificial Intelligence (AI) technology across various design aspects, including performance prediction, molecular generation, retrosynthetic reaction prediction, and reaction condition prediction, we discussed the existing gap between the current approaches in energetic molecular design and other materials design methods. By thinking about the causes of the gap, we present an outlook on the future developmental directions of AI-assisted energetic molecular design. Research indicates that AI has already been applied in property prediction and molecular generation of energetic molecular design, but requires further exploration in retrosynthetic reaction prediction, and reaction conditions prediction. AI-assisted design of energetic molecules holds broad promising application prospects. Data enhancement, transfer learning and high-throughput computing are expected to solve the problem of weak data of energetic molecules. Enhancing AI-assisted prediction of synthesis routes and reaction conditions for energetic molecules shows promise for achieving the automatic molecular design via whole process of “design-evaluation-preparation-verification”. AI-assisted energetic molecular design provides new possibilities for improving the level of energetic molecular design and helps to improve the efficiency of energetic molecule research and development.

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    • XUE Hao-qi, YU Yong-gang

      Online:January 05, 2024  DOI: 10.11943/CJEM2023206

      Abstract:In order to understand the ignition process of plasma jet in the liquid propellant electrothermal chemical gun, the spreading characteristics of plasma jet in simulative liquid propellant LP1846 were studied. A two-dimensional axisymmetric unsteady mathematical model of plasma jet spreading in the liquid was established, and the model was validateded with the experiments based on the liquid working medium of water. On this basis, the spreading process of plasma jet in the simulative liquid propellant LP1846 was numerically simulated. The morphological changes of plasma jet and the distribution characteristics of pressure, velocity and temperature in the jet field were analyzed. Results show that when the plasma jet expands in the simulative liquid propellant LP1846, there is turbulent mixing phenomenon due to Taylor-Helmholtz instability, and it becomes more and more intense. It is manifested by the protruding head of the jet and the axial elongation to form a tip, and the jet entrains the simulative liquid propellant medium to produce droplets in Taylor cavity, and the number of droplets gradually increases. At the same time, the necking phenomenon occurs near the nozzle hole during the expansion of plasma jet due to the simulative liquid propellant backflow. The jet field fluctuates due to the alternating action of expansion and compression waves, especially near the nozzle hole. The pressure field shows alternating distribution of high and low pressures, and the velocity field also shows similar distribution.

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    • HUANG Qi, LIU Li, JIN Bo, PENG Ru-fang

      Online:December 31, 2023  DOI: 10.11943/CJEM2023169

      Abstract:A new energetic iron-oxygen cluster, [Fe2(μ2-CH3O)(μ3-OH)(μ2-O)(BODTO2-)(H2O)]41), was synthesized by solvothermal method using 5,5"-{[3,3"-bis(1,2,4-oxadiazole)]-5,5"-yl}-bis(1-hydroxytetrazole) as ligand. The structure and thermal stability of compound 1 were studied by single-crystal X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis. The catalytic performance of compound 1 on the thermal decomposition of ammonium perchlorate (AP) was also investigated by differential thermal analyzer. Compound 1 crystallizes in cubic I-43d space group with a density of 1.506 g·cm-3. In the crystal structure, the nearby Fe3+ cations are interconnected to each other by bridging oxygen atoms. Through those connections, the iron(Ⅲ) cluster cages are formed. The peak thermal decomposition temperatures of compound 1 are 513.9 K, 617.6 K and 669.4 K, respectively. The detonation velocity and detonation pressure of compound 1 are 6.94 km·s-1 and 19.09 GPa, respectively. In addition, the impact sensitivity and friction sensitivity of compound 1 are 15 J and 360 N, respectively. After adding 10% compound 1 to AP, the high temperature decomposition temperature of AP decreases by 65 K, and the decomposition activation energy decreases by 82.2 kJ·mol-1, demonstrating the high catalytic activity of compound 1 for the thermal decomposition of AP and the great potential of compound 1 for application in energetic combustion catalysts.

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    • LIANG Peng-fei, CHEN Jin-fang, ZHAO Mei-ling, ZHANG Guo-hui, WANG Ya-li

      Online:December 26, 2023  DOI: 10.11943/CJEM2023078

      Abstract:Atomization performance of free impinging jets with unequal nozzle diameter of 60% Glycerol-water (60G) solution was investigated using PIV technique. The liquid sheet breakup characteristics and droplet behaviors were studied under different Weber numbers (51≤We≤1605), jet velocities (2.12 m·s-1u≤6.37 m·s-1) and nozzle diameters (nozzle 1: D1(left nozzle diameter)-D2(right nozzle diameter)=1.5-2 mm and nozzle 2: D1-D2=2-3 mm). The droplet distribution of the composite energetic material binder solvent diethylene glycol-water solution was also investigated. The results show that, as We number increases, liquid sheet breakup length increases first and then decreases from M3 beginning, the liquid sheet thickness and droplet diameter decrease while the droplet velocity increases. Nevertheless, as the nozzle diameter increases, changes in liquid sheet breakup mode are insignificant, and the liquid sheet breakup length, thickness and droplet diameter all increase, while the droplet velocity decreases. At the same time, the empirical correlation equations are obtained between liquid sheet breakup length, liquid sheet thickness, Sauter mean diameter D[3,2] and nozzle diameter, We number. After validation using the diethylene glycol-water solution, it reveales that with the increase of jet velocity, the droplet diameter decreases and the distribution becomes narrow after the impinging of diethylene glycol-water solution. The error range of D[3,2] values is within ±15% of the empirical correlation equation, which is consistent with the theoretical prediction results.

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    • DU Hui-ying, QU Zhi-hui, XIA Jiang-lu, YANG Ya-lin, LI Xin-yu, QIN Yi-feng, WU Bo, MA Cong-ming

      Online:December 26, 2023  DOI: 10.11943/CJEM2023201

      Abstract:1,3,5,5-Tetranitro-hexahydropyrimidine (DNNC) and 1,4,6,6-tetranitro-1,4-diazepane (TNDA) were synthesized from the reaction of 2,2-dinitropropane-1,3-diol with tert-butylamine and ethylenediamine, respectively. Their structures were characterized by nuclear magnetic resonance (NMR), fourier infrared spectroscopy(FT-IR), and single crystal X-ray diffraction. Meanwhile, their thermal behaviors and mechanical sensitivities were determined by differential scanning calorimetry-thermogravimetry(DSC-TG) and the BAM methods. Furthermore, isodesmic reactions and EXPLO5 were used to predict detonation parameters. The crystal structures indicate that the cyclohexane skeleton in DNNC and the cycloheptane skeleton in TNDA are both chair conformations. Both of them have extensive intermolecular and intramolecular non-classical hydrogen bonds. The results of DSC-TG show that the phase transition temperatures of DNNC and TNDA are 155.0 ℃ and 154.5 ℃, respectively. Furthermore, their peak decomposition temperatures are 215.3 ℃ and 205.9 ℃. In addition, DNNC and TNDA possess good mechanical sensitivity. Their impact sensitivities are 25 J and 17.5 J, and friction sensitivities are 144 N and 240 N. Besides, their theoretical detonation velocities are 8772 m·s-1 and 7828 m·s-1, and detonation pressures are 34.8 GPa and 25.0 GPa.

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    • Gan Ren-jie, YU Li-da, LI Hai-ning, ZHANG Wei-bin, LI Wei-bin, YANG Zhan-feng

      Online:December 25, 2023  DOI: 10.11943/CJEM2023198

      Abstract:The internal crack detection of polymer bonded explosive (PBX) is of great significance and engineering application value for its safety and structural integrity evaluation. In order to improve the imaging detection accuracy and image quality of PBX internal crack defects, the curved surface modified water immersion ultrasonic total focusing imaging method was proposed. On this basis, the delay multiply and sum (DMAS) technology was further combined. The ultrasonic imaging detection of the bottom crack defects of the Φ100.0 mm semi-cylindrical PBX was studied by water immersion method, and high-precision imaging characterization and high signal-to-noise ratio imaging of this bottom crack defect of the curved PBX was realized. The experimental results show that the crack defect height measurement error of the traditional TFM imaging algorithm is 12.0%, and the image signal-to-noise ratio is 1.37 dB. The height measurement error of this crack defect after surface correction is 3.6%, and the image signal-to-noise ratio is 2.13 dB. The crack defect height measurement error of the surface correction algorithm combined with DMAS is only 0.4%, and the image signal-to-noise ratio is 5.32 dB.

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    • LV Liang-liang, ZHANG Wei-bin, LI Gong-ping, PAN Xiao-dong, ZHANG Cai-xin, YANG Ya-fei, ZHANG Cui

      Online:December 12, 2023  DOI: 10.11943/CJEM2023212

      Abstract:The performance and dependability of PBX are significantly impacted by internal cracks. Accurate crack identification and quantitative analysis are crucial to evaluate the performance of PBX. Currently, the ability to identify and quantitatively analyze internal cracks of PBX needs to be further improved. Consequently, research on a deep learning-based method for PBX crack identification was conducted. Based on the popular deep learning networks, five different deep learning network structures were designed. This study aimed to compare the effects of network type, connection style, and pre-trained models on the recognition of PBX cracks. Internal crack images of PBX were obtained by CT technique. The training dataset of network was constructed using these crack images. The crack dataset was used to train five different types of networks. The performance of five networks was assessed based on Accuracy, F1, and MIoU. Select an outstanding network for PBX crack recognition and training based on the findings. The results indicate that, U-Net outperforms Seg-Net in pixel-level crack recognition and the Concatenate operation preserves more features compared to the Pooling Indices method. The pre-trained model (MobileNet and ResNet) can improve the training speed of the network, but its crack pixel-level recognition performance is reduced. The proposed method was applied to identify PBX crack, achieving pixel-level recognition. The results include a crack detection rate of 0.9570, a single pixel recognition accuracy of 0.9936, an MIoU of 0.9873, and a relative crack area of 0.7585, demonstrating superiority over traditional image segmentation methods.

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    • CAI Jing-jing, XU Xuan, CHEN Zhan-yang, YANG Jun

      Online:December 07, 2023  DOI: 10.11943/CJEM2023196

      Abstract:In order to explore the influence of the radial air gap in the hole on the directional penetration effect of shaped charge with/without metal liner and the detonation energy transfer process of explosive, ANSYS/LS-DYNA software was used to carry out the numerical simulation study when the air gap of the charge in the hole was 6, 8, 10, 12, 14 cm. The process of centralized release of energy from the shaped charge with metal liner forming an EFP and without metal liner forming concentrated detonation product flow as well as the depth of directional penetration into the borehole wall, was analyzed. The results show that when the air gap is less than 10 cm, the penetration depth of concentrated detonation product flow into the hole wall is increased by 53% (6 cm) and 29% (8 cm), respectively, compared with the average penetration depth of EFP. When the air gap was greater than 10 cm, the average penetration depth of EFP increased by 26% (12 cm and 14 cm) compared with the concentrated detonation product flow. The kinetic energy of EFP and concentrated detonation product flow per unit area through the hole wall on the shaped energy axis was calculated, it is found that when the air gap is small, the energy dissipation of concentrated detonation product flow in the air is less than that of EFP plastic deformation, and the penetration effect of concentrated detonation product flow on the hole wall is better. When the air gap is large, the density and kinetic energy at the axis of the concentrated detonation product flow are significantly reduced due to the spatial expansion of detonation products, while the EFP has high density and incompressibility, small energy dispersion and slow decay of kinetic energy, so the penetration effect of EFP on the hole wall is better than that of the concentrated detonation product flow.

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    • DING Zhi-hao, YANG Wei-tao, GAO Yu-chen, YANG Jian-xing, KONG Xin, YANG Bin

      Online:December 05, 2023  DOI: 10.11943/CJEM2023110

      Abstract:To study the effects of extrusion system nozzle runner structural parameters (cone angle, outlet diameter, and molding section length) on the fluid flow of energy-containing material extrusion process in the direct-in-writing-forming (DIW) technology, an extrusion model of high-viscosity energy-containing materials based on the Polyflow Extrusion module was established, and the model was verified by extrusion experiments under the working conditions of direct-write 3D printing. The study analyzed the effects of cone angle range (90°-130°), outlet diameter (0.75-2 mm), and molding section length (5-20 mm) on the extrusion process of high-viscosity energy-containing materials through the established model. The results show that the Polyflow Extrusion module can accurately simulate the flow behavior of composite energy-containing materials. When the cone angle is 100°, and the nozzle outlet diameter is between 1.5 mm and 1.75 mm, the extrusion process is relatively stable with small extrusion expansion. Additionally, as the length of the molding section grows, the required inlet pressure increases while the outlet expansion effect decreases.

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    • YUE Hong-li, ZHANG Cui, ZHANG Wei-bin

      Online:November 03, 2023  DOI: 10.11943/CJEM2023157

      Abstract:The molding granule is an intermediate for polymer-bonded explosive (PBX) components. Characterization of the physical parameters of granular system is of great significance to understanding the influence of different granule structure on the performance of PBX components. X-ray computed micro-tomography (XCT) and CT image processing were used to non-destructively characterize physical parameters (including granule diameter, volume fraction, porosity, sphericity and intrinsic density) of the granular random packing systems. The average granule diameter of granular systems is up to 1.04 mm, the volume fraction is up to 68.7%, the lowest porosity is 1.04%, the highest average sphericity is 0.93, and the highest density is 1.44 g·cm-3. Results show that the type of binder, explosive crystal composition, explosive crystal ratio and granulation process in the formulation of molding granules have important influences on the physical parameters of the granular system. Moreover, there is a correlation between physical parameters of granular systems. The more dispersed diameter distribution of granular system leads to the larger the average surface area of granules. The larger average granule diameter and lower average sphericity of granular system result in the higher porosity of the granules. The volume fraction of granular systems with larger average granule diameter is higher, and the volume fraction of the granule accumulation is independent of the sphericity when the average sphericity is large. This work provides a basis for understanding the physical parameters of random packing system of modeling granules and the in-depth study of the relationship between granular structure and material properties.

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    • CHEN Rong, MA Rong, WANG Zheng, REN Ke-rong, ZHANG Si-yuan, TIAN zhan-dong

      Online:October 23, 2023  DOI: 10.11943/CJEM2023133

      Abstract:The cast TiZrNbV refractory high entropy alloy (RHEA) has high structural strength and good energy release characteristics. As an energetic structural material, it needs to withstand complex dynamic load environments in engineering applications. Studying the spalling behavior of TiZrNbV refractory high entropy alloy and obtaining accurate dynamic constitutive parameters are vital for its engineering application. The spalling characteristics of TiZrNbV RHEA were studied by flat plate impact experiment using a 20mm light gas gun. Parameters such as spalling strength, Hugoniot elastic limit (HEL), and plastic strain rate were obtained, based on the free surface velocity history. The recycled specimens were analyzed using scanning electron microscopy (SEM), and the spalling characteristics of TiZrNbV RHEA at different strain rates were analyzed from both macro and micro perspectives. It was shown that the geometrically necessary dislocation of the samples significantly increased with the increase of loading velocity. The spalling strength of TiZrNbV RHEA increases with the loading strain rate and the loading stress, with values ranging from 0.93 GPa to 2.23GPa. The GTN-JC constitutive model parameters of TiZrNbV RHEA were obtained by calibrating the free surface velocity history of the spallation experiment with a flyer velocity of 580 m·s-1. The spallation behavior of the sample under 610 m·s-1 flyer velocity loading was calculated by using the fitted parameters. It was indicated that the free surface velocity curve of the spallation experiment performed well in simulating the spallation behavior of coarse-grained TiZrNbV RHEA. The simulation results show that the free surface velocity curve is consistent before the first tensile stage, which can be used for the dynamic analysis of sample spalling failure. The obtained parameters can provide reference for the engineering application of TiZrNbV RHEA.

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    • ZHAO Yang, JIN bo, PENG Ru-fang

      Online:November 10, 2023  DOI: 10.11943/CJEM2023177

      Abstract:In order to utilize the performance advantages of carbon nanomaterials, this article summarizes the application of carbon nanomaterials in the desensitizing technology of energetic materials. The effects of typical carbon nanomaterials, such as graphite, carbon nanotubes, graphene and its derivatives, fullerene and its derivatives, on the reduction of impact, shock wave, and friction sensitivity of energetic materials, and explored the desensitization mechanism of different carbon nanomaterials was discussed. Finally, the development prospect of carbon nanomaterials in this field of desensitizing technique of energetic materials is forecasted. It is considered that optimizing the preparation process of carbon nanomaterials and energetic materials, deeply understanding the properties of carbon nanomaterials and conducting functional modification, regulating the interface interaction between carbon nanomaterials and energetic materials and further exploring the desensitization mechanism of carbon nanomaterial will be the focus of future research.

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    Vol, 32, No.2, 2024     Multiscale Mechanical Behaviors of Solid Propellant

      >Editorial
    • >Energetic Express
    • WANG Zhe-jun

      2024,32(2):117-117, DOI:

      Abstract:

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    • >Perspective
    • QIANG Hong-fu, WANG Zhe-jun

      2024,32(2):3-8, DOI: 10.11943/CJEM2023272

      Abstract:

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    • >Propulsion and Projection
    • LI Yong-qiang, LI Gao-chun, LIN Ming-liang

      2024,32(2):124-132, DOI: 10.11943/CJEM2023225

      Abstract:As a composite material composed of fillers and matrix, the damage of hydroxylated polybutadiene (HTPB) propellant mainly involves particle breakage, matrix fracture, and debonding of the bonding interface layer. To further explore its structural damage and mechanical performance evolution under external loading, a combination of micro CT, high-speed CCD camera, and all atom molecular dynamics simulation was used to analyze the multi-scale damage of the propellant under in-situ loading. The results indicate that the typical damage process of the propellant begins with the failure of the bonding interface layer, extends to the growth of debonding pores, evolves through the merging of pores, accelerates the collection of local large deformations, and terminates at the fracture of the matrix. Meanwhile, the interface binding energy and stress concentration degree cause the large ammonium perchlorate (AP) particles to debond first, and the porosity and strain exhibit an exponential function relationship. Furthermore, the traction separation curve of the micro interface layer conforms to an exponential cohesive force model, where the initiation and expansion of micro voids disrupt their cohesion, while the molecular spacing affects the evolution of stress.

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    • MAIMAITITUERSUN Wubuliaisan, ZHOU Tao, WU Yan-qing, HOU Xiao, ZHOU Cheng-zhe

      2024,32(2):133-141, DOI: 10.11943/CJEM2023220

      Abstract:In order to study the damage evolution and mechanical properties of solid propellants, uniaxial tensile and stress relaxation tests were performed on NEPE propellant. The resulting stress-strain curves and relaxation master modulus curves were obtained. A nonlinear viscoelastic constitutive model considering microscopic damage was developed under finite deformation. This model enables multiscale analysis of the mechanical response of propellants by incorporating the evolution of microvoids with various factors, including temperature, strain rate, confining pressure, and cyclic stress softening. The model was then implemented into ABAQUS with the parameters determined based on experimental data. Subsequently, the model was employed to predict the mechanical response of NEPE propellant under different loading conditions. The results demonstrate that the model accurately predicts the uniaxial tensile response of propellants under wide temperature ranges (223-333 K) and loading rates (1-200 mm·min-1). Moreover, the model exhibits reasonable predictability in cyclic loading, confining pressure tests, and biaxial tensile tests, thereby validating its effectiveness under complex stress conditions. Notably, the model necessitates only a small set of model parameters and can be easily programmed into commercial software, providing theoretical guidance for the multiscale analysis of the structural integrity of solid rocket motors.

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    • WANG Gui-jun, ZHOU Tao, WU Yan-qing, HOU Xiao, HUANG Feng-lei

      2024,32(2):142-151, DOI: 10.11943/CJEM2023218

      Abstract:To accurately predict the cracking of propellant grain during ignition at low temperatures, a cross-scale analysis method coupled with global-local unidirectional contracting was proposed. For Nitrate Ester Plasticized Polyether (NEPE) propellant, uniaxial tensile tests at low temperature and intermediate strain rate were carried out, and the typical failure modes of the propellant were obtained. The results show that the ignition of solid rocket motor grain at low temperature can be analyzed successfully with macroscope method based on the developed nonlinear viscoelastic constitutive model, and the location of the dangerous point for propellant grain was obtained. Meanwhile, a mesoscopic particle filling model considering the particle-matrix interfacial debonding and particle fracture was established, and the analysis results on a macro scale were applied to the corresponding mesoscopic representative volume element (RVE). Finally, based on the established mesoscopic failure criteria of the propellant, it is shown that the structural integrity of the propellant grain meets the requirements under low-temperature ignition conditions. Furthermore, the proposed contracting cross-scale analysis method can be used as an effective method to predict the cracking behaviors of the propellant grain during ignition at low temperature.

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    • PEI Shu-di, QIANG Hong-fu, WANG Xue-ren, WANG Zhe-jun

      2024,32(2):152-161, DOI: 10.11943/CJEM2023231

      Abstract:In order to study the effect of loading Angle on the failure mechanism of HTPB propellant bonding interface, microCT was used to scan and reconstruct the bonding interface in-situ during uniaxial tensile process, and the damage evolution process was characterized. Then, the meso-structural parameters and damage variables were introduced into the cohesive force model, and the meso-damage evolution process of the adhesive interface under different loading angles was obtained. The results show that the initial dehumidification of AP particles at the bonding interface mainly starts from the weak interface layer near the interface, and the direction is along the shear component direction of the interface. The fracture pattern of the interface is related to the shear Angle. The smaller the resultant force and the Angle of the interface, the easier the crack propagation to the propellant/liner interface, whereas the crack propagation is more likely to occur between AP particles. Finally, compared with the experimental results, the accuracy of the calculated results is verified, and the damage evolution law of the propellant bonding interface structure under different loading angles is revealed.

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    • ZENG Yi, HUANG Wei, CHEN Jia-xing, XU Jin-sheng, CHEN Xiong, WU Rui

      2024,32(2):162-174, DOI: 10.11943/CJEM2023248

      Abstract:This research investigates the mesoscopic damage mechanisms in hydroxyl-terminated polybutadiene (HTPB) propellants under thermal-mechanical coupling. Experimental characterization and theoretical analysis were employed to analyze these mechanisms at different environmental temperatures (50, 70, and 90 ℃) and loading cycles. At 50 ℃, the propellants underwent approximately 3000 and 10800 loading cycles; at 70 ℃, 1800, 3600, and 7030 cycles; and at 90 ℃, around 1800 cycles. The findings indicate that the mesoscopic damage in HTPB propellants, exacerbated by thermomechanical coupling, is more pronounced than that caused by a single aging factor. This damage primarily results from two processes: thermal degradation of the matrix, diminishing both its load-bearing capacity and adhesion to particles, leading to particle dewetting; and the subsequent exacerbation of the matrix"s thermal degradation by this dewetting. The above interaction makes the mesoscopic damage more severe. Moreover, the damage intensifies with increasing aging temperature, but extremely high temperatures modify the mesoscopic damage mechanism. Furthermore, the study emphasizes the importance of selecting an appropriate number of loading cycles to assess significant mesoscopic damage in HTPB propellants. Notably, substantial damage occurs when the loading cycle ratio () at 50 ℃ and 70 ℃ exceeds 0.281 and 0.330, respectively.

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    • LI Shi-qi, QIANG Hong-fu, CHEN Tie-zhu, WANG Xue-ren, WANG Zhe-jun, WANG Guang

      2024,32(2):175-182, DOI: 10.11943/CJEM2023232

      Abstract:To analyze the mesostructure evolution behavior of nitrate ester plasticized polyether (NEPE) propellants under uniaxial quasi-static tensile load, in-situ observation test was conducted on NEPE propellants during the tensile process using Micro CT. The size and an shape of ammonium perchlorate (AP) particles and initial defects in NEPE propellants were characterized. The failure process of the mesostructure in the propellant during uniaxial tensile process was obtained, and the quantitative analysis of the changes in meso-damage of NEPE propellants was carried out using porosity. The reason for the changes of macro-mechanical properties is explained based on the evolution laws of the structure of NEPE propellant on the mesoscale. The results indicate that the initial defects size of NEPE propellant is small and the volume ratio is low, with an average value of 0.12%. In the process of uniaxial quasi-static tension, the meso-failure process of NEPE propellant mainly includes three stages, pores nucleation, growth and convergence. Although the volume fraction of AP particles is low, it is often the start of meso-damage because of easy debonding. HMX particles will also debonding after a certain degree of debonding of AP. The influence of HMX debonding behavior should be considered when analyzing the macro-mechanical properties of NEPE propellant. The nucleation and growth of a large number of mesoscopic defects is the reason why the macro-mechanical properties properties of NEPE propellant enter the nonlinear section. The phenomenon that the increase of macroscopic stress lags behind the increase of strain is more and more obvious because of the continuous convergence of mesoscopic defects. During the loading process, the porosity shows a change trend of slowly increasing first, then sharply increasing and finally increasing tends to be gentle. The change law of porosity can not only quantitatively reflect the evolution stages of the mesoscopic defects of NEPE propellant, but also have a certain corresponding relationship with the changes of the macroscopic mechanical properties of NEPE propellant.

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    • WANG Ran, WU Yi, BAI Long, ZHANG Yi-ming, WANG Ning-fei

      2024,32(2):183-192, DOI: 10.11943/CJEM2023119

      Abstract:In order to investigate the uniaxial compression mechanical behavior of four-component HTPB propellant under wide temperature and wide strain rate ranges, uniaxial compressive mechanical performance tests of propellant were conducted under wide temperature and strain rate ranges based on universal material testing machine, high-speed hydraulic servo testing machine, split Hopkinson pressure bar, and programmatic constant temperature and humidity testing machine. Stress-strain curves of HTPB propellant under 10-4-103 s-1 at -40, -25, -10, 20 ℃ and 50 ℃ were obtained, and the segmented uniaxial compression rate-temperature constitutive relationship of HTPB propellant was established. The results indicate that the mechanical response of HTPB propellant exhibits a significant rate-temperature correlation. At any strain rate, its mechanical response undergoes staged changes, i.e., linear elastic stage-nonlinear yield stage-strain softening or strain hardening stage. Moreover, at high strain rates, the strain softening phenomenon after the nonlinear yield behavior is significantly weaker than that at low and medium strain rates. In addition, at high strain rates, as the temperature decreases, the changing rate of the stress-strain curve gradually slows down; while at low and medium strain rates, the changing rate of the stress-strain curve gradually increases as the temperature decreases. The mechanical strength of HTPB propellant increases significantly with decreasing temperature. When the temperature drops from 50 ℃ to -40 ℃, the maximum stress under wide strain rate increases from about 2.2-8.8 MPa to 11-22 MPa. The segmented rate-temperature constitutive relationship constructed based on the experimental data has a better fitting effect at higher temperatures, which can better predict the mechanical behavior of HTPB propellant.

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    • ZHOU Dong-mo, XIE Xu-yuan, WANG Rui-min, LIU Xiang-yang, HUI Bu-qing

      2024,32(2):193-203, DOI: 10.11943/CJEM2023224

      Abstract:To study the formation mechanism of residual stress/strain of the nitrate ester plasticized polyether (NEPE) propellant grain during the curing and cooling stages, the temperature field, curing degree field and stress/strain field of the propellant were numerically analyzed via ABAQUS finite element software. The results show that there are temperature gradient and curing rate gradient in the NEPE propellant grain during the curing process at 50 ℃. The temperature and the curing rate are notably higher at the center of the grain, and they eventually reach a consensus at the end of curing. The temperature difference in the propellant does not affect the final residual stress/strain. The total residual stress/strain during curing and cooling obey the principle of stress/strain superposition, and they are mainly composed of the curing shrinkage stress/strain and thermal stress/strain during cooling. For the total residual stress, the proportions of the two stages are approximately 20% and 80%, respectively, and for the total residual strain, the proportions are about 30% and 70%, respectively. Compared with the traditional method, the residual stress/strain calculated in this study have the same distribution characteristics, but the values are smaller.

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    • WANG Yao-xiao, WANG Xiao-ying, CHEN Chen, TAN Zhu-yun, ZHOU Xing

      2024,32(2):204-210, DOI: 10.11943/CJEM2023178

      Abstract:To establish the correlation between the microstructure and mechanical properties of high nitrate plasticized polyethylene glycol (PEG) based polyurethane in nitrate ester plasticized polyether (NEPE) propellant, biuret triisocyanate (N-100) was used as a multifunctional curing agent and mixed with nitrate ester plasticized PEG for curing to prepare PEG elastomers with curing parameters ranging from 1.2 to 1.7. The microstructure of PEG elastomer crosslinked network was studied by uniaxial tension, X-ray diffraction, low field nuclear magnetic resonance and equilibrium swelling test methods. Furthermore, the effects of different network chain structures on the mechanical properties of PEG elastomer were analyzed. The results show that the PEG elastomer is amorphous due to its high plasticized properties. Meanwhile, the total ratio of suspended tail chains to free chains is more than 85%, the structural integrity of the crosslinked network is low, and the elastomer exhibits high elongation, low tensile strength and low initial modulus. Secondly, all the tensile strength and initial modulus of elastomer are positively correlated with the crosslinked chain density. The maximum elongation increases first and then decreases with the increase of physical temporary entanglement chain density. CU-5 elastomer with a curing parameter of 1.6 has the most complete cross-linked network. At the same time, the corresponding tensile strength is 0.80 MPa, and the maximum elongation is 1456%, which indicates that the mechanical properties are the best. Finally, the chain density measured by equilibrium swelling method and low field nuclear magnetic resonance satisfy the magnitude relationship of νL,A<νs<νL,A+B.

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    • >Reviews
    • DUAN Lei-guang, WANG Xue-ren, QIANG Hong-fu, WANG Zhe-jun

      2024,32(2):211-229, DOI: 10.11943/CJEM2023252

      Abstract:The health condition of solid rocket motors largely depends on the real-time status of the propellant. Therefore, monitoring the propellant status is an important foundation for ensuring the structural integrity and reliability of solid rocket motors. We provides a comprehensive review of research progress in the monitoring of propellant status from four aspects: environmental status monitoring, chemical status monitoring, mechanical status monitoring, and integrated application of monitoring data. The necessity of propellant status monitoring is highlighted, and the research achievements and shortcomings in propellant status monitoring are summarized from multiple perspectives. Furthermore, development ideas are proposed for monitoring technology and the application of monitoring data. The analysis suggests that real-time monitoring technology should focus on embedded sensor compatibility, new sensing technology, and long-life technology. In terms of the application of monitoring data, efforts should be made to establish databases, diagnostic and predictive health management systems, in order to promote the development of digital twin technology for the full life of solid rocket motors using finite element model updating methods.

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