bluuebunny/crossref_metadata_2025 huggingface dataset:
Shock Initiation Characteristics of CL-20-Based Cast Cured Explosives with High Aluminum and Ammonium Perchlorate Contents
Authors: Yang K , Chen L , Liu D Y , Zhang B , Lu J Y , Wu J Y
Published: December 2024

The addition of a large amount of aluminum and ammonium perchlorate will change the sensitivity of the explosive. At present, there is lack of deep understanding of the shock initiation characteristics of CL-20 based mixed explosives with high aluminum and AP contents, which is important for the optimization of the explosive components and safety use. In this paper, the electromagnetic particle velocity gauges were embedded in the wedge-shaped explosive to measure the particle velocity during shock initiation, and then numerical simulation model was constructed, based on the experimental data, the parameters of reaction rate model and equation of state were calibrated. By combining experiments and numerical simulations, the shock initiation characteristics and effects of aluminum and ammonium perchlorate contents on the initiation process were investigated. Results show that the two kinds CL-20-based cast cured explosives with high aluminum and AP contents are more sensitive than PBXW-115. The change of aluminum and ammonium perchlorate significantly changed the shock initiation behavior, which could lead to intersection point in the Pop relationship. Based on the characteristics of shock initiation, it can be inferred that the shock initiation process of explosives follows different mechanisms under low and high pressure. Under relatively low pressure, the shock initiation process of explosives is mainly dominated by the formation and growth of “hotspots”, while under higher pressure, the rapid reaction of CL-20 itself will dominate the initiation and rapid growth of detonation.
Numerical Calculation for Form Function of Gun Propellant with Simple Mesh Generation
Authors: Zhi-gang Guo , Hui-fang Yu , Rui Wu , Man-man Li , Lun Wei , Qiang Li , Qiong-lin Wang , Xiao-mu Wen
Published: December 2024

A numerical model was built for the form function of gun propellant. To simplify the heavy mesh work, the 3D-grain of propellant would be transformed into the porous medium in control volumes. Then, the iterative calculation of solid fraction matrix could be established to reflect the burn-back of burning surface. Finally, based on the weighting sum of matrix element, the percentage of the propellant mass burned (Ψ) varying with the relative propellant thickness (Z) could be obtained as the numerical results for the form function. The step size of Z is dependent on the size of control volume for the geometry simplification, and the accuracy of Ψ-Z relies on the modification factor connecting with the gradient of solid fraction in the iterative process. The present model could adapt to different geometric conditions, such as 7-pore grain and spherical propellant. The deviation magnitude of Ψ would be less than O(10−2).
Study on the Co-crystal Transition Process and Mechanism of CL-20 and HMX in Propellant Formulation
Authors: Zou Pangangjing , Li Shichun , Huang Shiliang , Zhang Haobin , Liu Yu , Li Liangbin , Xu Jinjiang
Published: December 2024

The integration of CL-20 into solid propellants to enhance their energy levels has emerged as a focal point in the research of high-energy solid propellants and the use of CL-20 as a partial substitute for traditional oxidizers in propellant formulations has emerged as a viable method for propellant modification. However, research indicates that the microstructure and crystal form of CL-20 and HMX may undergo changes due to external stimuli and energy induction, resulting in significant deterioration of the propellant’s mechanical and combustion properties, as well as its safety. We were surprised to find that CL-20 and HMX can form co-crystal not only in the nitric ester plasticizer like DOS but also in some specific binders, such as GAP and HTPE, and revealed that the solvent’s capacity to dissolve two explosives is the key determinant in the formation of co-crystal.
Research on the Technology of Micro-Pyrotechnic Reagent Charging
Authors: Wang Zao , Zhang Song , Wang Yanlan , Wang Wei , Zhang Fang
Published: December 2024

The technology of micro-pyrotechnic reagent charging is crucial for the controlled delivery and performance of pyrotechnic compositions used in applications ranging from signalling and illumination to propulsion and explosives. This review provides a comprehensive overview of recent advancements in micro-pyrotechnic reagent charging, focusing on techniques for loading pyrotechnic compositions, integration methods, performance optimization, and safety enhancements. The discussion includes both traditional and innovative approaches, highlighting emerging trends and future research directions.
Research on sensitivity experiment and RF dudding assessment of EED
Authors: Xiangfei Ji , Chunqiang Wei , Tuan Zhao , Hognzhi Yao
Published: December 2024

This article refers to radio frequency(RF) sensitivity test and RF dudding assessment method of MIL-STD-1576, select the two kinds of typical bridge-wire electric explosive device(EED) to carry on RF sensitivity experiments and direct current(DC) sensitivity experiments before and after exposure in radio frequency environment, analyze and compare EED DC sensitivity on the impact of 10% RF sensitivity, and assessing the RF dudding possibility on EED. Test results shows that made 10% RF ignition sensitivity as detonation standard, both of two kinds of samples ignited. 4 out of 40 in 1# sample ignited and 3 out of 40 in 2# sample ignited. And detonation test of 10% RF ignition energy did not change the DC ignition feature of two kinds of EED (confidence is 95%). Preliminary study RF dudding assessment method, provide test data and testing methods for deeply researching the RF dudding experiment and assessment method on EED.
Preparation and Penetration Performance Verification of Low Fluorine Polymer Content Reactive Liner
Authors: Peiyu Li , Sheng Zhou , Zhenyang Liu
Published: December 2024

To address the combined effect of shaped charge on target penetration performance and post penetration effect, several high-density materials added Al/PTFE reactive liner were designed. Apply the theory of particle size distribution to design the particle size of formula components. And conduct SEM and EDS analysis on the reactive liner made. Static explosion tests were conducted to verify the penetration of several designed formulas into steel targets, and EDS and SEM analyses were conducted on the penetration channels. The experimental results show that the penetration depth of the liner with high-density particles significantly increases, and the addition of copper is more conducive to improving the penetration depth than the addition of tungsten. However, as the amount of tungsten added further increases, the penetration depth shows a downward trend. At the same time, the effects of copper and nickel with similar densities on the performance of the reactive liner were compared, and the results showed that adding copper improved the penetration depth better than adding nickel. This has certain reference value for the design of high-density fluoropolymer based reactive liner.
Molecular dynamic simulations of adiabatic self-reaction in Al@Ni core-shell nanoparticles
Authors: Chen Yongpeng , Yuan Dazhong , Cao Wenli , Lv Ruiheng
Published: December 2024

Al@Ni core-shell nanoparticles are attracting significant attentions for using as a promising material. In this paper, the self-reaction thermochemical behavior of Al@Ni nanoparticles was studied by molecular-dynamics (MD) simulations to characterize the final reaction temperature and self-heating rate. The analysis was carried out in canonical-constant temperature (NVT) and microcanonical-constant energy (NVE) ensembles using an embedded atom method. The ignition temperature was in the range of 700 K ∼ 1300 K, the core-shell thickness ratio of 1:1 ∼ 7:1 and the nanoparticle radius of 2 nm ∼ 8 nm were considered. When the ignition temperature was 1100 K, the nanoparticle radius was 8 nm, the core-shell thickness ratio was 3:1, the final reaction temperature was highest of 1955 K. As the ignition temperature was 1100 K, the nanoparticle radius was 4 nm, the core-shell thickness ratio was 3:1, the self-heating rate was highest of 3.04×1012K/s. These results obtained from the MD simulations of Al@Ni nanoparticles are helpful to understand the energy release mechanism.
Preparation and combustion analysis of B@PDA@AP with dual-core shell structure
Authors: Ma Shuai , Huang Hongyu , Zhang Ting , Zhao Shuai
Published: December 2024

B@PDA and B@PDA@AP core-shell structured composites were synthesized successfully via the solvent-antisolvent method. PDA, functioning as an effective binder, modifies the B surface and anchors AP onto it. Analysis of the stable combustion process of B@20%PDA@15%AP and B/15%AP showed that B@20%PDA@15%AP exhibited more intense and complete combustion, with larger flame morphology and faster flame propagation. PDA enhances mass and heat transfer between B and AP, accelerates reaction rates, and mitigates AP decomposition splash, sustaining better gaseous phase combustion. This research offers strategies for tailoring the energy release of the B/AP and advancing its application in energetic materials.
Influence of cavity crystal defects on the thermal ecomposition mechanism of NTO
Authors: Wang T B , Li L J , Tao Y T , Ning L Y , Jin S H , Cen K , Lu Z Y
Published: December 2024

The impact of cavity crystal defects on the thermal decomposition process of 3-nitro-1,2,4-triazol-5-one (NTO) was examined utilizing the reaction molecular dynamics method. A perfect crystal model of NTO and crystal models with cavity defects at concentrations of 0.78%, 1.17%, 2.34%, 3.13%, and 5.10% were constructed, and the potential energy and product changes in the isothermal mode at 2500 K were calculated. The impact of cavity defects was analyzed for the initial reaction stages, and the thermal decomposition reaction rate of 2500 K was calculated. The results demonstrate that at 2500 K, the complex reaction of NTO is enhanced, with the denitration reaction emerging as the dominant initial reaction type, followed by the ring-breaking reaction, and the proton transfer reaction occurring with a lower frequency. The principal intermediate products were CO2, NO2, HON, etc. The final products included N2, N4, H2O, HO2, and O2. In the range of 0.78% to 2.34% cavity content, the initial chemical reaction rate of NTO exhibited a slowing down trend with the increase of hole concentration. A collapse in the crystal structure accompanied this. Conversely, an acceleration was observed in the initial chemical reaction rate of NTO when the cavity concentration exceeded 2.34%.
Effects of oxidizer on the secondary reaction of aluminum and metal acceleration for CL-20-based aluminized explosive
Authors: Gao Chenyu , Liu Yan , Lyu Zhongjie , Yan Junbo , Bai Fan , Huang Fenglei
Published: December 2024

The addition of oxidizing agents in the explosives could enhance the burning rate and the reaction degree of aluminum powder due to the increase of oxidizing gas content in the detonation products. Therefore, it affects the metal acceleration ability of the explosive. The current study is concerned with investigating the metal acceleration ability of the CL-20-based aluminized explosive containing oxidizer affecting metal shells through standard cylinder tests. The diameter of the cylinder is 50 mm. An all-fiber displacement interferometer system with a photon Doppler velocimeter took into account the continuous measuring of the cylinder wall velocity over time. The detonation velocity was calculated by the velocity jump time interval of the cylinder wall. BKW equation was applied to calculate the detonation pressure. The effects of oxidizer on the ignition time and the reaction degree of aluminum powder were analyzed by replacing aluminum powder with lithium fluoride for comparison. According to the cylinder wall velocity energy source, empirical formula about explosive composition and the cylinder wall kinetic energy was fitted. The results show that CL-20-based aluminized explosive detonation velocity and aluminum content is linearly correlated, and oxidizer-containing explosives detonation velocity can be equivalent to oxidizer-free explosives within a certain margin of error. With the addition of oxidizer, detonation pressure, and the base explosive content no longer show the same increasing and decreasing relationship. When the aluminum content is 5% and 30%, the ignition time of aluminum powder is 4.81μs and 1.66μs earlier respectively. When the aluminum content is 5%, the reaction degree of aluminum powder reaches 1. The aluminum powder reaction rate for oxidizer-containing explosives and oxidizer-free explosives is mutually fast and slow. When the aluminum content is 30%, aluminum powder reaction degree and aluminum powder reaction rate for oxidizer-containing explosives are higher than that of oxidizer-free explosives throughout. Based on the fitted relationship equation, it is predicted that the maximum value of kinetic energy of the cylinder wall is obtained at 10% aluminum powder content with 10% oxidizer.
Investigation of Combustion Properties Optimizing of Composite Modified Double Base Propellant Containing CL-20
Authors: Xu S Y , Yao E G , Pei Q , Zhang Z H , Jiang H Y , Li M , Hao H X , Zhao F Q
Published: December 2024

The effect of combustion catalysts which are several proportions of A-Pb, A-Cu and carbon on the combustion properties of composite modified double base (CMDB) propellant containing hexanitrohexaazaisowurtzitane (CL-20) were investigated by uniform design. The proportion of the three materials is optimized. The result shows that A-Pb, A-Cu and carbon can affect the combustion properties of CL-20-CMDB propellant. The effect of single A-Pb or carbon on the propellant combustion properties is obvious between 2 MPa and 8 MPa. The effect of single A-Cu on the propellant combustion properties is obvious between 14 MPa and 22 MPa. There is positive interactions of carbon with A-Pb or A-Cu between 2 MPa and 4 MPa and A-Pb with A-Cu or carbon are obvious. The calculation shows that the effect on adjusting the combustion properties of CL-20-CMDB propellant when the proportion of A-Pb, A-Cu and carbon is 3/0.8/0.2.
Research on recrystallization technology of CL-20 based on microfluidic
Authors: Zihao Zhang , Siyu Xu , Hanyu Jiang , Jin Yu , Ergang Yao , Yubao Shao , Xi Chen
Published: December 2024

Using microfluidic technology, CL-20 was prepared at different concentrations, flow ratios, and treatment times. The particle size, morphology and crystal form of the samples are characterized. The results show that metastable state β-CL-20(d50 = 1.04 μm) and a narrow particle size distribution is preferentially precipitated at 0.3 g·mL-1 and a flow rate ratio of 1:20, which needs certain treatment time to transform into ε-CL-20. It demands a considerable amount of time to transform CL-20 into ε-CL-20 via standing suspension, and the obtained ε-CL-20 crystal morphology is superior. Stirring can effectively curtail 80% of the time, but the acquired ε-CL-20 crystal morphology is suboptimal. After agitating the suspension for 1 hour and leaving it to stand for 4 hours, the obtained sample is ε-CL-20(d50 = 50.35 μm), and its surface is sleek and defect-free.
PBX Wide temperature range deformation detection applying in-situ photogrammetry
Authors: Rongfang He , Weibin Zhang , Guofang Gao , Taiwen Wu
Published: December 2024

Abnormal environment especially wide temperature range is an important cause of changes in the physical structure of PBX. And has a significant impact on its reliability and safety performance. In order to master the geometric deformation law of PBX in the wide temperature range, a “dual lens” in-situ photogrammetric method for PBX wide temperature range geometric deformation measurement with a “low expansion reference bar” as the measurement reference is proposed. The ultra-low expansion ceramic gauge block is used as the detection object for experimental research, and the feasibility and detection ability of this method for wide temperature range deformation measurement are verified. The experiment shows that the repeatability of point coordinate detection can reach 0.006mm, and the repeatability of different temperature conditions can reach 0.01mm. In situ monitoring was conducted on the corresponding points of PBX within the temperature range of −20 ℃ to 70 ℃. The data showed that deformation was related to the structure and positively correlated with the size of the structure. The size data before and after temperature cycling showed that it was suspected that after experiencing a low temperature environment of −20 ℃, the structural characteristic size increased irreversibly.
Effect of Accelerated Aging on the Dynamic Mechanical Properties of RDX Based Explosives
Authors: Hu X Y , Wang Y X , Tang J J , Qu K P
Published: December 2024

To reveal the effect of accelerated aging on the mechanical properties of RDX based explosives, dynamic compressive experiments under passive confinement were conducted using a split Hopkinson pressure bar system. The stress-strain behavior of passively confined explosives at different strain rates (500/s∼1100/s) and different aging times (0day∼28days) was obtained. The results show that the compressive mechanical properties of RDX based explosives exhibits obvious strain rate hardening effect, especially the yield strength of unaged specimens. With the increase of aging time, the axial stress corresponding to a specified axial strain before yielding increases. The nonlinear relationship between axial yield stress and constraint ratio is established, and the fitting results are in good agreement with the experimental results for both unaged and aged explosives.
The Influence of Liquid Components of GAP Propellant on Its Mechanical Properties
Authors: Yubao Shao , Siyu Zhang Zihao Xu
Published: December 2024

In response to the problem of poor mechanical properties of glycidyl azide polymer (GAP), a branched high molecular weight glycidyl azide polymer (B-GAP) was used as the adhesive to prepare a propellant with a solid component ratio of 78%. The effects of different network modifiers such as PL1, PL2, and PL3 on the mechanical properties of this type of propellant were studied. The results showed that the sample containing both PL1 and PL3 had the highest tensile strength at 0.712 MPa, but the elongation at break decreased to 35.7%; The sample containing only PL3 has the highest elongation at break, which is 73.3%, and the maximum tensile strength is only 0.315MPa. And the propellant containing PL1 has a lower loss factor; Next is PL3; The loss factor containing PL2 is relatively high.
Structure, nonisothermal decomposition kinetics, thermal safety and mechanisms of improving stability and sensitivity of RDX/expanded graphite embedment composite
Authors: Ma X L , Zhang Z , Fan J , Shang F Q , Ma X , Du X C , Tao Y , Zou H M , Lv X J
Published: December 2024

To understand structure, properties and mechanisms of improving safety of RDX/expanded graphite (EG) embedment composite further and promote the application of EG in energetic materials, embedment stability, formability, detonation velocity, thermal stability, thermal safety and microscopic mechanisms of improving stability and sensitivity of the composite were studied in depth as a supplement to our previous work. Embedment stability was good. Formability (charge density of 1.76 gcm−3) and detonation velocity (7577 ms−1) were acceptable considering the content of EG was 13 wt%. Thermal stability and safety were proved to be improved by kinetics parameters and self-accelerating decomposition temperature. The former was obtained by forty-one kinds of kinetics model functions and six kinetics equations from nonisothermal thermolysis process of RDX. Molecular dynamics were employed to understand microscopic mechanisms for improving safety. Results showed that after being embedded in EG, strength and number of intermolecular forces in RDX crystal increased by 5.45 % and 14.38 %, and N-NO2 maximum bond length of RDX molecule was shorted from 1.60 to 1.56 Å indicating a stronger intermolecular interaction and a safer trigger bond. All these results suggested that RDX/EG embedment composite was a more stable and insensitive system with a certain practical value.
Thermal performance, mechanical sensitivity and low speed impact ignition characteristics of PTFE based aluminum alloy active materials
Authors: Yuan Junming , Wang Nan , Huang Runsheng , Zhou Hanpeng
Published: December 2024

To solve the problems of low energy release efficiency, slow reaction rate, and long ignition response time of Al/PTFE, the idea of introducing aluminum zirconium alloy powder instead of traditional Al powder is proposed in this paper. By utilizing its high calorific value, high enthalpy value, and high activity, the reaction rate and energy of PTFE based aluminum alloy active materials are promoted and enhanced, which ultimately improved and enhanced the energy release efficiency. Aluminium zirconium nickel based active materials were developed using aluminum zirconium alloy powder, and their thermal properties and mechanical sensitivity were tested. The temperature isostatic pressing preparation process based on prefabricated column was also explored. The research results indicate that the Al/Zr/Ni/PTFE formula has a higher exothermic value when Al reacts with PTFE, and it triggers a reaction in the Al/Zr/Ni alloy powder during the reaction stage; The addition of aluminum zirconium alloy powder reduces the impact and friction sensitivity of Al/PTFE materials, with Al/Zr/Ni/PTFE aluminum alloy active materials showing a slight improvement; The ignition response and energy release characteristics of Al/Zr/Ni/PTFE aluminum alloy active materials under hammer impact are significantly improved compared to Al/PTFE. Therefore, the aluminum zirconium nickel based active material system is one of the important research directions in the future.
Research on BEVFormer-based Underwater Object Detection and Localization Model Trained with Migrated Dataset
Authors: Liu Xing , He Yuan , Wang Hancheng , Huang Yu , Chen Chulun , Pan Xuchao , Jiao Junjie , Fang Zhong , He Yong
Published: December 2024

The complexity and variability of the underwater environment have presented a significant technical challenge in the detection and localization of underwater object. In this paper, an underwater object detection and localization method based on the BEVFormer model is presented and experimentally verified for effectiveness. The BEVFormer model incorporates spatial cross-attention and temporal self-attention, leveraging information from both temporal and spatial scales to enhance robustness. The Generative Adversarial Network CycleGAN was employed to generate the underwater dataset U-nuScenes, based on the nuScenes dataset. Results show that the method presented in this paper achieved 24% mAP and 0.35 NDS on U-nuScenes under the condition of utilizing only visual information.
Object Detection Based on Edge Enhanced YOLOv5
Authors: Nie Hui , Ning Yan , Liu Zhentao , Ma Long , Zhang Ruolan
Published: December 2024

In order to address issues that arise in complex scenarios, an edge-enhanced YOLOv5 algorithm is proposed. The fusion of edge features with original feature maps serves to enhance the accuracy of the detection process. The algorithm employs Sobel and Canny operators for edge extraction, integrating these with low-level feature maps through addition and concatenation. Testing in urban and desert settings demonstrated that the enhanced models exhibited superior accuracy and a reduction in false and missed detection compared to the original YOLOv5. This methodology has the potential to enhance target detection performance in complex environments.
Fast Implementation of Image Preprocessing for SAR Scene Matching Guidance
Authors: Chen Shuailin , Nie Hui , Chen Jinyu , Dang Yuanjie , Zhang Zhaoming , Lang Haowen
Published: December 2024

The design of SAR scene matching guidance scheme and the hardware allocation of algorithm module are discussed in this paper. Aiming at the requirement of SAR image preprocessing module, a fast robust feature extraction preprocessing method based on FPGA is designed, and the fast implementation of Gabor filter and wavelet transform is completed. Through the hardware-in-the-loop simulation module test and experimental verification, the FPGA-based pre-processing fast implementation is about 60 times shorter than the DSP processing time, and the results of FPGA, DSP and digital simulation in the hardware-in-the-loop simulation process are consistent. The proposed method not only shortens the processing time of scene matching guidance system, but also ensures the accuracy of SAR image matching.
Simulation and testing analysis of the vibration characteristics of the panoramic sight platform during the driving of a certain tank
Authors: Xingwang Liang , Xiaobing Pang , Weiliang Yuan , Jie Li , Yunrui Wan , Yanfei Su , Qiong Hou
Published: December 2024

To study the vibration characteristics of the panoramic sight platform during the driving of a certain tank, the vibration transmission path of the tank was analyzed, modal simulations were performed on the turret, the carrier platform of the panoramic sight platform, the vibration characteristics of the panoramic sight platform during the driving of tank under different working conditions were tested. The results showed that the vibration modes of the turret were located at the location of panoramic sight platform in the third, sixth, and eighth modes, with natural frequencies of 52.439 Hz, 65.012 Hz, and 87.064 Hz, the main response frequency of each structural component of the panoramic sight platform ranged from 46.5 Hz to 52.5 Hz, which was consistent with the main excitation frequency of the turret and the simulated natural frequency. Therefore, resonance was prone to occur in the panoramic sight platform. The simulation and test results have certain engineering guidance significance for the design and overall layout research of tank panoramic sight platform.
Dynamic response analysis of missile-sled separation in warhead rocket sled test
Authors: Yang Zhen , Yang Yang , Fan Kun
Published: December 2024

The warhead’s attitude upon hitting the target stands as a pivotal factor influencing its dynamic damage effect. This paper addresses the issue of interference posed by the sled and separation device on the warhead’s attack angle during endpoint effect rocket sled tests. Employing an impact dynamics analysis method, we simulate the dynamic response of the missile-sled separation process. Four models are devised, combining two types of rocket sled structures and two variations of arc rail devices with distinct parameters. Comparative analysis is conducted on the sled’s separation distance, the warhead’s attitude, and the sled’s stress. We optimize the rocket sled structure to ensure unhindered separation of the warhead and the sled, followed by verification tests. Analysis reveals that a small curvature radius and insufficient sled stiffness lead to structural failure. Consequently, the sled interferes with the warhead, impacting the target’s attack angle. To address this, we introduce a middle snap ring and slipper to reinforce the sled, along with an increased curvature radius. These two enhancement measures effectively resolve the separation interference issue between the sled and the projectile. The attack angle shift from −0.5° to 1.1° in two sled tests, thus fulfilling the experimental requirements.
Explosion impact dynamics diagnosis of protective structures based on optical coherence velocimetry technology
Authors: Shi Y X , Peng Y C , Xing Y D , Wang L Y , Huang X F
Published: December 2024

The dynamic response of protective structures under explosive conditions is an important criterion for evaluating structural protection. Obtaining the instantaneous response speed and displacement of specific parts inside the protective structure under strong impact conditions is a key and difficult point in evaluating the impact effect and safety of protective structures.. Aiming at the shortcomings of traditional measurement methods with large errors and poor anti-interference ability, optical coherence measurement method is introduced. A multi-channel photonic Doppler velocimetry system and an inertial slider-type displacement sensor are designed to achieve horizontal dynamic displacement without relying on external static references. Numerical simulation technology is also used to simulate the process of shock wave action. The measurement results show that there are plastic and elastic deformations in the protective structure under this explosive shock condition, with maximum plastic deformation of 6.5 mm and peak speed of 2.83 m/s. The peak value of the first axial velocity wave obtained by simulation is close to the measured value, which verifies the accuracy of the simulation method to a certain extent. However, there are still some differences indicating that the model parameters still need to be continuously optimized. This system has the advantages of long measurement time, strong anti-electromagnetic interference, and a large range of speed and displacement. It can grasp the velocity and displacement response and attenuation law of the protective structure, providing an important reference for evaluating impact effects and protective structure safety.
Numerical study on consecutive water entries of twin spheres under the influence of current
Authors: Wang X , Lyu X
Published: December 2024

The consecutive water entries of projectiles into the water flow involve complex flow field and motion interference phenomena, resulting in unpredictable projectile trajectories. In this paper, a three-dimensional numerical model with six-degree-of-freedom technology is conducted to investigate the parallel water entry of two spheres. The explicit volume of fluid model is adopted to track the air-water interface, and the shear-stress transport k-ω model is used to delineate the turbulence structures. The multi-overset technology is employed to track the independent movement of the two spheres during water entry. The numerical results evaluate the effect of water flow on the consecutive water entry process in terms of cavity dynamics, flow field evolution, and hydrodynamic characteristics. During the upstream water entry, the flow-induced cavity tilting reduces the peak lateral force coefficient of the trailing sphere by about 28.9%. However, the constant impact of the current leads to an increase in the trajectory deviation by about 53.2%. The attractive force exerted by the inclined cavity on the downstream side sphere provides sufficient attraction to deflect it toward the upstream side by overcoming the lateral force generated by the water flow. The variation of the peak lateral force coefficient is close to 200%. However, this deflection disappears upon increasing the lateral distance of two spheres.
Experimental study on ignition characteristics of fuel tank impacted by a reactive fragment
Authors: Chen A R , Li X D , Zhou L W , Ji Y Z Y , Shi Z X
Published: December 2024

The experiment of high-velocity reactive fragment impacting the fuel tank had been conducted. The influence of the fragment velocity, the fuel type, and the oxygen content on the ignition of the fuel had been studied. The high-velocity impact of the fuel tank could give rise to highly spurt and atomize of the fuel, which could lead to combustion more intense. The fuel spurted from the tank in the form of burning particles or atomized liquid. The critical impact velocity of the reactive fragment required for aviation kerosene tank to be ignited is lower than that of the same type of diesel tank. The ignition of the fuel had three typical characteristics:(1) The fire spreading from the front to the back of the panel. (2) Hot particles are ejected from the fuel tank as the spurted-fuel ignited. (3) The fire died out, and then re-burned in the fuel spurt. The half-filled fuel tank was ignited from the inside of the tank, and the process of the combustion reaction could be more intense than the case of full-filled. Under the experimental conditions in this study, the critical pressure and specific impulse of the diesel tank are 1.64 GPa and 4.86 × 103 Pa·s, respectively. When the impact pressure is higher than 1.39 GPa, or the specific impulse is over 4.66 × 103 Pa·s, the aviation kerosene tank could be ignited. With the increase of impact velocity, the damage degree of the reactive fragment to the fuel tank gradually increases, which could be divided into three levels: long cracks on the sidewall, incomplete unfolding, and complete unfolding of the sidewall. In this research, through the method of experiment, the ignition characteristics and influencing factors of high-velocity fragment impact on the fuel tank are studied, but the ignition mechanism of the reactive fragment impacting the fuel tank has not been deeply studied. In the future, it is necessary to focus the research on the hydrodynamic ram caused by the fragment impacting the fuel tank and the resulting fuel spurt for the building up of the ignition theory of the fuel spurt.
Numerical study on breakage of high energy beam controlled projectile with random defects
Authors: Zhou X , Men J B , Li M , Jin W
Published: December 2024

Based on the rapid modeling of high energy beam controlled projectiles, controlled area data processing and model secondary development, the controlled projectile model characterization method with random defects can simulate the internal formation of the projectile after the high energy beam scans it by using random numbers. To solve the defects, AUTODYN-3D software was used to conduct numerical simulation analysis of the explosion drive and rupture process of typical projectiles. The results show that the defects distribution has little impact on the initial velocity of fragments formed by high energy beam controlled projectiles, but it can make the projectiles break more evenly and reduce the formation of large fragments (>6.0g) and small fragments (<1.5g). As the proportion of defects continues to increase, the percentage increase in the total number of effective fragments formed by the fragmentation of the controlled projectile shows a decreasing trend. The research results have reference value for the control of electron beam controlled projectile fragment formation.
Ballistic performance of ZnO-modified aramid fabric under extreme temperatures
Authors: Xu Y J , Zhang H , Huang G Y
Published: December 2024

Aramid fabric was widely used in bulletproof armor due to its excellent mechanical properties. Previous studies have shown that high and low temperature had a great impact on the mechanical properties of aramid fibers. This work used ZnO particles to modify aramid fabric to improve its ballistic performance under extreme temperature environment via SEM imaging, quasi-static tensile test, yarn pullout test, ballistic impact test and numerical simulation. The tensile strength and failure strain of modified yarn was 13.3% and 25.9% higher than those of neat yarn under extreme temperature. The ballistic limit velocity of ZnO modified aramid fabric was 124.1% and 164.1% higher than that of neat fabrics under high and low temperature environments, and the areal density was only increased by 8.2%. The weakening of the ballistic performance of aramid fabric was due to micro-surface damage caused by irregular crack defects on the fiber surface and changes in molecular orientation. The numerical simulation results were in good agreement with the ballistic impact test. The influence of changes in fabric mechanical parameters on the ballistic impact protection mechanism was elucidated, further demonstrating the significant improvement of ballistic performance of ZnO modified fabric under extreme temperature.
A parametric study on sandwich structures with star-shaped honeycomb core under blast loads
Authors: Li Xuelin , Li Zhuangzhuang , Guo zhuoyu , Zhou Yue , Han Shuo , Mo Zonglai , Li Jun
Published: December 2024

A finite element analysis of the blast resistance of the star-shaped honeycomb (SSH) core sandwich structure was carried out by using the CONWEP calculation model, with maximum deformation, energy absorption, and area specific energy absorption as the indicators of the explosion resistance. Based on the finite element method verified by experimental data, the influence of the structural parameters of each part of the SSH core sandwich panel on its anti-explosion performance was quantitatively investigated. The results show that the increase of the connecting ligament L and cell wall angle θ can improve the explosion resistance of the SSH core sandwich panel; the maximum deformation of the sandwich panel and the energy absorption capacity of the sandwich panel decreases with the increase of the three thickness coefficients (cell wall thickness t, the front panel thickness tf
, and the back panel thickness tb
); the greater the TNT equivalent, the greater the maximum deformation of the sandwich panel, and the greater the energy dissipation; the use of SSH core sandwich panels as a protective structure in explosion protection systems significantly reduces the maximum deflection and enhances the energy absorption compared to solid panels of equal mass, respectively.
Effect of boundary constraints on the response of reinforced concrete structures to high overload impacts
Authors: Meng Xin , Wang Lei , Huai Ronghua , Yan Huadong
Published: December 2024

The study of the dynamic response and destruction characteristics of concrete structures under high overload impact conditions is a hot topic in the academic and engineering circles. In this study, the process of the “Turbojet-6” engine striking a reinforced concrete structure with strength of C60 at a speed of 230m/s was simulated and analysed. The calculation results show that different forms of boundary constraints have almost no effect on the resistance of reinforced concrete structures to destruction, but have a great impact on the deformation of reinforced concrete structures, and the stronger the boundary condition constraints, the greater the structural deformation.
Numerical simulation study of high-speed fragment penetration into a certain ship bulkhead structure
Authors: Zhang Zhenyi , Xia Fangchao , Cao Zhongchen , Yuan Fei , Wang Peng
Published: December 2024

In this paper, the numerical simulation method is used to study the penetration behavior of high-speed fragments into the ship cabin wall structure under different speeds, angles and structural parameters. By analyzing the key parameters such as stress distribution, deformation and damage propagation, the physical law of high-speed fragment penetrating bulkhead structure is revealed. The results show that the damage effect of different shapes of fragments on the target is significant: under the same conditions, the penetration ability of spherical fragments is the strongest, while the penetration ability of cylindrical fragments is poor at high angle impact. Different regions of stiffened plate have different penetration resistance to fragments. The penetration resistance of the center and long rib regions is strong, while the short rib and non-rib regions are weak. The numerical simulation method adopted in this paper is consistent with the empirical formula, which verifies the accuracy of the method and provides reference for the structural design and optimization of ship cabin wall.
Numerical calculation and analysis of anti-penetration of ultra-high strength bullet shielding layer
Authors: Guo Taiping , Sun Yuxin , Luo Jia , Zhao Dongzhi , Zheng Wei , Liu Yongxiang
Published: December 2024

This research deals with the numerical investigation of ballistic protection proided by a combination of steel and reinforced concrete. Firstly, the parameters of the material model were calibrated based on the experimental data, and numerical simulations were carried out with existing experiments to verify the rationality of the material model and numerical simulation methods. Subsequently, the numerical simulation of the penetration of a typical ground-penetrating projectile into the G50/RC composite target at a velocity of 350m/s was carried out to analyze the stress wave transmission and ballistic performance during the penetration process, and the critical penetration depth was obtained. Finally, by changing the steel type and the number of steel plate layers, the best composite target combination is obtained. The simulation results show that the G50/RC composite target can effectively withstand the impact of conventional ground-penetrating warheads, and make them break or explode outside the shielding layer. At a projectile velocity of 350 m/s, the critical penetration thickness of BLU-109/B, BLU-122 and BLU-137 prototypes is 16, 17 and 19cm, respectively. Under the penetration of BLU-137, 40cm 45# steel can achieve the same protection effect as 19cm G50; The double steel plate composed of 12cm G50 steel and 12cm 45# steel has excellent penetration resistance. By comprehensive analysis, the same composite target using double steel plate can greatly increase the anti-penetration performance of the bomb shield and reduce the cost of engineering construction.
Modeling Study of Shell Damage to the Typical Light Armored Vehicles
Authors: Xuncheng Guo , Dongjiang Zhang , Xuelei Feng , Qiong Qi , Lei Zhang
Published: December 2024

This study focuses on the destructive mechanisms and high-precision numerical simulation models of guided shells frequently encountered in combat conditions for damaging light armored vehicles. Based on the modes of shell action and the vulnerability characteristics of light armored vehicles, a systematic analysis of damage patterns was carried out, revealing their destructive effects. Through induction and analysis, a characterization method for the shell’s power field was established. By combining the experimental conditions and data of typical shell damage to steel plates, numerical simulation modeling and calculations of the shells were conducted, obtaining more accurate simulation parameters for the shells. A numerical simulation model of a light armored vehicle under the action of shells was further established. By utilizing the damage tests and data of typical shells on light armored vehicles, the model was calibrated and validated. The maximum error between the simulation calculations and experimental tests was less than 20%, indicating that the established large-scale model of typical shells against light armored vehicles possesses high engineering accuracy. The research findings aim to provide theoretical and simulation guidance for the design of ammunition power, practical damage assessment, and target protection design.
Study on the secondary fragment formation characteristic and search reconstruction algorithm
Authors: W J Bai , L He , F D Dong , S Liu
Published: December 2024

Secondary fragments formed by the projectile core penetrating the target plate are closely related to the accurately evaluation of the damage effectiveness. To address the problem of unclear characteristics of secondary fragments, a search reconstruction algorithm for secondary fragments is established in this paper. First, the penetration process is numerically simulated to obtain all the particles that can characterize the secondary fragments. Then, non-independence matrices reflecting the interactions among all particles are constructed. Finally, all the fragments are screened according to the non-independence matrix to obtain the number of fragments and the mass, volume, velocity, center-of-mass coordinates of each fragment. As verified by the penetration test, the search reconstruction algorithm proposed in this paper is capable of accurately characterizing the secondary fragments while taking into account the computational efficiency. In addition, it can be seen from the penetration test and simulation results that at 0.6m from the target plate, the scattering radii of the secondary fragments are basically the same for different initial velocities of the projectile core, and the same is true at 1.4m from the target plate. The damage mode of the irregular fragments formed by the projectile core penetrating the target plate on the fiber layer in the bulletproof vest is dominated by shear damage. As the velocity of the fragments decreases, the corresponding shear effect is weakened, and the fiber layer produces strong tensile deformation, the vest appears to bend and delamination phenomenon. With the initial velocity of the projectile core increasing, the greater the deformation of the projectile core after penetrating the target plate. The more fragments produced by the projectile core, the smaller the average mass and the less volume of the fragments. The radial velocity of the fragments increases with the increase of the initial velocity of the projectile core, and the scattering radius of the fragments shows the same trend.
Numerical simulation research on the influence of aluminum reaction rate on the explosion damage effect inside the runway
Authors: Jin Zhenhao , Jiang Chunlan , Wang Zaichen , Hu Zhongtian
Published: December 2024

Aluminum-containing explosives are characterized of a high detonation heat and a long work duration, making them suitable for causing internal explosive damage to targets such as runway. The reaction rate of aluminum during the explosion process will affect the energy output process of the explosive, thereby affecting the destructive effect on the runway. In order to study the damage law of aluminum reaction rate on runway targets, this paper takes TKX-50 based aluminum explosive (TAE) as an example and uses finite element software to simulate the explosion process of the charge inside the runway. A systematic study was conducted on the explosion process and mechanism of aluminum-containing explosives with different aluminum reaction rates in the runway from the perspectives of damage process and energy transfer. Research has shown that during the stress wave failure stage, increasing the aluminum reaction rate can effectively increase the stress wave energy, enabling it to form a larger range of failure in the runway. In the stage of gas expansion, the reaction rate of aluminum directly affects the process of gas pressure attenuation in the cavity, thereby affecting the work ability of the product on the runway. When the aluminum reaction rate coefficient is a=5e-4, the aluminum reaction rate matches the gas leakage rate, allowing the heat energy released by the aluminum reaction to effectively compensate for the internal energy loss caused by gas leakage, slowing down the rate of gas pressure attenuation, and causing greater damage to the runway. In addition, the law of the influence of aluminum reaction rate on the effect of explosive damage in the runway is well adapted under different conditions of charge quality and burial depth.
Study on the Centrifugal Mixing Process of PBX Simulants
Authors: Li Yuanyuan , Niu Yulei , Jiang Fan , Nan Hai , Bu Yufan , Liang Bin
Published: December 2024

A centrifugal mixer for plastic-bonded explosives (PBXs) is developed as the existing planetary mixers cannot be used to prepare small-amount explosives. The working principle of the new mixer is also introduced. Using PBX simulants composed of composite binder and inert filler, the effects of process parameters such as rotating speed, mixing time, solid content, and mixer type on the temperature rise of the simulants during mixing are studied. Results show that with the increase of rotating speed and solid content, the mixture’s temperature rises drastically, especially within the first 3 min of mixing. After that, there is no obvious change in the temperature. Under the same process conditions, the mixture’s temperature in a polytetrafluoroethylene (PTFE) container rises more significantly compared with that in an Al container, especially when the rotating speed is higher. After 3 ∼ 5 min of centrifugal mixing at 1500 rpm in an Al container, the materials are uniformly mixed, with ensured operational safety. The results show that the mixing process can be used for PBXs.