bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Factors Influencing the Reaction Intensity of Composite Propellants with Different Casing Materials under Slow Cook-off
Authors: Liang Jiahao , Nie Jianxin , Zhang Haijun , Zhang Leilei , Li Yingjun , Guo Xueyong , Yan Shi
Published: December 2024

By conducting slow cook-off tests on solid composite propellants, the combustion response characteristics of propellants under different casing materials were investigated. Propellant slow cook-off combustion experiments were designed and carried out. Combining the morphological changes of propellant thermal decomposition weight loss with theories of material mechanics and heat transfer, the heat transfer process and physical state of the propellant before ignition were examined to explore their effects on after ignition reaction intensity. The results indicated that the reaction intensity varied with different casing materials. When the casing material is 45# steel, spontaneous ignition occurred at 214.88, with a slider speed of 14.83 m/s, classifying the reaction as deflagration. For 2A12 aluminum casing material, spontaneous ignition occurred at 199.13, with a slider speed of 0.71 m/s, classifying the reaction as combustion. When the casing material is carbon fiber composite, the reaction was classified as combustion. Different casing materials influence the reaction intensity through their thermal physical parameters and casing constraint strength, providing guidance for the selection and design of casing materials and constraints in slow cook-off combustion of motors.
Study on the gas pressure impact test of gun propellant and fluid-solid coupling dynamics simulation
Authors: Zhang R H , Chen D Y , Liu J H , Zhao H L , He C H , Jin J W
Published: December 2024

In order to reveal the mechanical response characteristics of high-energy propellant under high pressure gas impact, the gas pressure impact test and fluid-solid coupling dynamics simulation of propellant are carried out. The propellant gas pressure impact test device is established. The propellant gas pressure impact tests are conducted under different quality of depressant and thickness of iron pressure relief fragments. The gas pressure-time curve, gas pressure rise and decreasing rate are obtained. It is found that longitudinal and transverse cracks occur locally in propellant under high pressure impact. In order to reveal that mechanical property change of propellant under gas impact, the simulation study on fluid-solid coupling dynamics of gas pressure impact test is carried out using ANSYS Workbench multi-field coupling platform. The flow field pressure in the device and the change process of fixed propellant stress and deformation are obtained. The error of monitoring point simulation and test pressure is 5.3%. The maximum peak value of internal flow field pressure reaches 71.6MPa. The average value of maximum stress and maximum deformation of fixed propellant reaches 220MPa and 1.77mm respectively. It reveals the mechanical response characteristics of propellant under high pressure gas impact.
The Equivalence Method of Overload Characteristics of Detonation Control System based on High-speed Deep Penetration of Composite-medium Thick Target
Authors: Yan Huan , He Hongwei , Hu Qianyu , Huang Dan
Published: December 2024

In response to the improvement of the penetration ability for kinetic energy projectiles, the projective structures have been continuously increasing in thickness and developing in the direction of composite-medium materials, resulting in increasing complexity in testing the overload characteristics of the detonation control system. Addressing this difficulty, this paper analyses the range test data of the high-speed deep penetration of the composite-medium thick target. It is found that the overload characteristics has the long pulse width and multiple overload peaks, which is quite different from penetrating the single-medium target. Taking the overload characteristics of the detonation control system when penetrating composite-medium thick targets as the starting point, the influence of the thickness of the medium layer on overload characteristics is analysed, based on the deep penetration overload theoretical model of composite-medium thick target. It is found that by changing the medium layer in the composite-medium thick target, the overload peak and pulse width can be better considered in the equivalence study of overload characteristics. The equivalence composite-medium thick target is designed by the FE simulation, the overload characteristics of double overload peaks and long pulse width in the range test are well simulated. The equivalence method of the overload characteristics of the detonation control system is formed based on the composite-medium thick target, and it can also provide technical support for the reliability design of the anti-thick detonation control system.
Numerical Simulation of Modular Charge Security under Different Drop Postures
Authors: Wu S , Yu Y G , Zhao Z Y , Wang Y Q , Liu C
Published: December 2024

The impact of an accidental drop of modular charge may inevitably cause the charge to fail. In order to deeply understand the safety of modular charge under drop impact conditions and promote the safety evaluation and structural design of modular charge, a dynamic finite element model of modular charge was established based on nonlinear finite element theory. The module charge drop test was simulated by using ANSYS/LS-DYNA software. A numerical simulation was performed to evaluate the influence of drop postures on the stress, strain and acceleration response of the modular charge. The stress, strain and acceleration data of the modular charge when it dropped from a height of 1.5m onto Q235 steel plate, with three drop postures: bottom-downward vertical drop, horizontal drop and a 45° inclined drop. Results show that the ranking of dropping postures in terms of risk of modular charge rupture from highest to lowest is: 45° inclined drop, horizontal drop, and vertical drop. Under the condition of 45° drop, the maximum stress and strain in the modular charge are observed, with the minimum acceleration and the longest time to reach peak values. Under all three drop postures, the safety risk areas are located at the bottom of the combustible cartridge. The bottom of the combustible cartridge is the first to rupture when the modular charge is dropped at a 45° angle. Therefore, in the subsequent research on the improvement of modular charge, the impact resistance of combustible cartridges should be focused on.
Propagation characteristics of explosion shock waves in air under different temperature and pressure conditions
Authors: Hang Peng , Wenjin Yao
Published: December 2024

In order to study the propagation characteristics of explosion shock waves in air under different temperature and pressure conditions, stress wave theory and detonation wave theory were first used to analyze the propagation characteristics of shock waves. Combined with numerical simulation results, the propagation characteristics of explosion shock waves were comprehensively analyzed and verified. The following conclusion was drawn: the higher the pressure, the larger the peak value of shock waves at the same spatial position, and the greater the specific impulse of shock waves, Shortening of shock wave propagation distance; The higher the temperature, the less the peak pressure changes at the same spatial position, the smaller the specific impulse of the shock wave, and the longer the propagation distance of the shock wave.
Effect of aluminum powder particle size on quasi-static pressure and temperature in confined space explosion of aluminized explosives
Authors: Liu Zheng , Nie Jianxin , Kan Runzhe , Guo Xueyong , Yan Shi
Published: December 2024

Aluminum powder particle size is a crucial parameter concerning the energy release of aluminized explosives. This study aimed to examine the effect of single aluminum powder particle size and particle size gradation on the explosive energy release characteristics of aluminized explosives in confined spaces by using a self-developed confined explosion experimental device. Aluminized explosive samples having aluminum powder particle sizes of 6, 24, and 43 μm and particle size gradation of 6/24/43 μm were tested for explosion parameters generated by an internal explosion. The results indicate that the quasistatic pressure of the measured aluminum powder samples decreased gradually with the increase of the particle size. The quasi-static pressure of the particle size gradation explosive samples was the largest, and the quasi-static pressure increased by 5.0%, 9.9%, and 12.0%, respectively, compared with a single particle size. The highest peak temperature was observed for the 6 μm particle size sample. However, the highest equilibrium temperature was obtained for the particle size gradation sample, indicating that particle size gradation promotes the reaction of aluminum powder in the afterburning stage; this helps maintain the temperature of a confined space for a certain duration and increase the energy release of the aluminized explosives.
Effect of water environment on penetration parameters of shaped rod jets
Authors: Cheng Yubo , Jiao Junjie , He Yong
Published: December 2024

This study conducts a comparative analysis of the influence of the water environment on the large conical angle rod jet, juxtaposed with its behavior in air. Utilizing the LS-DYNA finite element software, the research simulates and examines the operational dynamics of a rod jet under identical shaped charge configurations in both water and air environments. The findings indicate that the compressibility of water is significantly lower than that of air, leading to a more rapid deceleration of the penetrating body upon entry into the aqueous medium. This results in a pronounced increase in the counter-impact force exerted by the water on the rod, which, in turn, is transmitted rearward. This backward transmission of force diminishes the pressure within the central region of the penetrating body, effectively reducing the velocity gradient and promoting the continuity of its motion through water.
Research on the effect of thin tungsten patch on the fracture behaviour of steel shells under detonation
Authors: Guo Q S , Ma Y , Meng Y P , Zhang X M , Zhang J J , Fang Z , Wang C T
Published: December 2024

To achieve controlled fragmentation of the shell, a pre-control method was designed, which involved adhering high-impedance thin tungsten patches to the outer wall of the shell according to specific rules. Based on the transmission and reflection characteristics of shock waves at different interfaces, the effect of waves on shell fracture was analyzed, revealing that the shell at the gap between the patches fractured first. Through numerical simulation studies, it was found that adhering thin tungsten sheets externally could effectively control the fragmentation of the shell, with shear fracture being the prior mechanism for shell fragmentation. When using rectangular patches, there were fewer connected fragments, and the effective fragment generation rate reached 67.90%, higher compared to the other two patch methods. Comparison revealed that the effective length χ was directly proportional to the effective mass of the fragment when using a rectangular patch, and χ=1.3 resulted in a pure shear fracture mode, forming the most uniform fragments. The velocity distribution along the axial direction was consistent under different patches, with the highest fragment velocity occurring at a distance of 3/4 from the initiation point. When rhombus patches were used, the average fragment velocity was higher than that of the other two patch methods.
Experiments and numerical simulations on ceramic-metal composite targets penetrated by a 7.62 mm armour-piercing projectile
Authors: Liu Z D , Wang S , Han Z Q
Published: December 2024

In order to explore the protective performance of ceramic-metal fibre composite target plate, a lightweight composite target plate consisting of aramid cloth, silicon carbide ceramic, TC4 titanium alloy, and ultra-high molecular weight polyethylene fibre plate was designed. The effects of adhesive type, stacking sequence and delamination on the protective performance of the target plate were researched through the ballistic impact test on the protective target plate with 7.62mm armour-piercing bullets. The effect of thickness variation of ceramic metal on the protective properties of target plate was investigated by LS-DYNA finite element software. It was found that the bonding effect of silicon carbide ceramics with TC4 was better than that of AB adhesive when the silica gel was used as the bonding adhesive. When the ceramic metal thickness dimension is certain, the ceramic delamination will weaken the protective structure performance, and the performance of the metal plate as the back support of the ceramic layer is better than that of the ceramic covered before and after the metal layer. The energy efficiency of the ceramic-metal structure is optimal when the ratio of the thickness of silicon carbide ceramic to TC4 is 4.84:1 for a certain surface density.
Research on the Method of Calculating the Wear Extent of the Rocket Sled Slipper Based on Pin-on-Disk Tests
Authors: Zhu Xiao , Yan Hua-dong , Cheng Ming-can , Qu Xiao-ting
Published: December 2024

This paper carries out the pin-on-disc wear test on the wear characteristics of the slipper-rail material under different loads and different speeds, and the research results show that: with the increase of load, the wear extent increases, but the relationship between speed and wear extent is not single; through linear regression analysis method to fit the pin-on-disc test wear extent, we get the wear coefficient k = a + b(pv) + c(pv)
2 of the slipper material when mating with the U71Mn steel, where a = 2.604 x 10−5, b = 1.115 x 10−10, c = 4.944 x 10−16. Then, from the wear loss effect of the slipper, the formula for calculating the wear extent of the slipper was derived, and the wear thickness of the slipper was calculated when the sled was accelerated to 1700m/s in a project.
Necking Analysis of High-speed Penetrating Projectile against Reinforced Concrete
Authors: Chen B H , Zou H H , Meng L , Wang W G , Dai X H , Wang K H , Zhou G
Published: December 2024

The complexity of penetrating projectile’s structure is not adequately considered in existing research of penetration. Based on this actuality, high-speed reinforced concrete penetration experiment is conducted and necking at the front end of projectile’s shank is found to be the most significant phenomenon. Mindlin–Herrmann rod theory is adjusted with elastoplastic constitution and finite element method to be applied in penetration calculation. Cavity expansion theory is applied as the longitudinal and radial load estimation. The calculation results denote that both longitudinal and shear waves propagate along the projectile when penetration begins. The necking is achieved instantly during the first circulation of stress wave propagation and the uniaxial compression state at the shank’s front end makes this structure vulnerable of initial yielding. Mindlin–Herrmann rod theory successfully explains the origin and influence zone of necking, while the necking’s degree and radial contraction at projectile’s tail require further investigation.
Analysis of numerical calculation methods for oblique penetration of projectiles into concrete targets
Authors: Yan Liu , Danyong Wang , Yijiang Xue , Zhenming Qin , Huamin Jia , Zhenqiang Huang , Zhendong Gao
Published: December 2024

This article uses finite element software ANSYS/LS-DYNA to analyze the numerical simulation method of projectile oblique penetration into concrete targets. FEM method is commonly used for numerical simulation of projectile penetration into concrete targets, but there is a problem of large deformation of concrete when penetrating concrete targets obliquely, and FEM method is prone to mesh distortion. Based on the experimental results of oblique penetration of the projectile into concrete, this article uses FEM, SPH, and FEM-SPH numerical simulation methods to obtain the numerical simulation results of oblique penetration into concrete targets at different velocities and incident angles of the projectile. The results from the deflection angle of the projectile and the depth of the crater indicate that compared with using FEM and SPH methods separately, FEM-SPH method has higher consistency with experimental results in simulating the oblique penetration of the projectile into concrete.
Simulation Study on Output Characteristics of Pyrotechnic Devices in Deep Water Environment
Authors: Ma Hongliang , Xue Yuanyuan , Yin Guofu
Published: December 2024

In order to study the output characteristics and influencing factors of pyrotechnic devices for weapons and equipment in deep-water environments, a simulation model of the action process of the model separation bolt under water load was established, and the changes of separation velocity and displacement of the pyrotechnic device with different variables were calculated with propellant charge, water depth and load shape as variables. The results indicate that, With the increase of propellant charge, the separation velocity of the separation bolt gradually increased, and the maximum separation velocity rise rate increased. With the increase of water depth, the velocity attenuation accelerates with the decrease of velocity, and the maximum velocity at 10 m depth is 74 m/s larger than that at 5000 m depth, and the displacement at 3 ms is about 150 times. After 5 ms, the reduction of spherical, conical and cylindrical load velocity increased sequentially, and the decrease of cylindrical load speed was 10 times that of spherical shape.
Glide-extended Projectile with Rotating Wings for Launch Stress Analysis
Authors: Chen Jinquan , Wang Xugang
Published: December 2024

During the launch process of a glide-extended projectile, the rotating wings on its back will experience extremely high overloads. To meet the reliability requirements of the wings, it is necessary to design the wing shape reasonably and select the wing material appropriately. This paper conducts a stress simulation on a subsonic airfoil, optimizes the shape of the wing, reduces the maximum stress the wing experiences during launch, and verifies through simulation that the aerodynamic characteristics of the optimized wing meet the mission requirements. Subsequently, stress analysis is performed on wings made of four different materials, and aluminum alloy is ultimately selected as the wing material, followed by modal analysis.
Size effect analysis of projectile penetrating semi-infinite concrete target
Authors: Liu Zihan , Zhang Xianfeng , Liu Chuang , Deng Yuxuan , Hou Xianwei , Fang Yizhou
Published: December 2024

Accurately assessing the damage effects of deep-penetrating weapons is of great significance for promoting the development of large-caliber kinetic energy penetrator warheads and the design of engineering protection. To accurately predict the penetration depth of projectiles into semi-infinite concrete targets, this paper derives through rigorous dimensional analysis and similarity theory that the maximum coarse aggregate size not scaling with the scale ratio and the strain rate effect are among the factors preventing small-scale projectile penetration tests on concrete targets from being extrapolated to full-scale tests. Based on the cavity expansion theory, the predictive model for the penetration depth of projectiles into concrete is derived. The accuracy and generality of the established model are verified through 20 groups of experimental data under different conditions, with an average prediction error of about 6.7% and a maximum error not exceeding 20%. Comparative analysis with the Wiffen’s model, Forrestal’s model, Wu’s model, Y.Peng’s model, and Feng’s model demonstrates the superiority of the model established.
Study on predicting plate deformation under double charges coupled loading based on GBR-RFR stacking model
Authors: Chu Shanyong , Liu Yan , Xu Zixi
Published: December 2024

In modern information warfare, quickly and accurately destroying enemy key targets is crucial. The single damage mode of traditional ammunition no longer meets the demands of complex combat environments. Therefore, it is necessary to explore the damage modes and plastic deformation of targets under double charges coupling to achieve precision strikes. This paper studies the predictive model of plate deformation under double charges coupling. A double charges synchronous explosion was used as the means of coupling shock wave loading, and double charges experiments on the damage to Q235 metal plates were conducted. Based on the experimental results, a three-dimensional finite element numerical simulation model was established and its accuracy was verified. Further simulation conditions were added, and data on the plastic deformation at the center of the metal plate under double charges synchronous loading were calculated. A predictive model for the plastic deformation at the center of the metal plate was constructed based on the GBR-RFR stacking model, thereby obtaining a predictive model for the plastic deformation at the center of the metal plate under double charges synchronous loading. Through dual-source synchronous explosion experiments and finite element numerical simulations, plastic deformation data at the center of Q235 metal plates under different loading conditions were obtained. Validation results show that the finite element simulation model can accurately predict the deformation of the plate. On this basis, the predictive model constructed based on the GBR-RFR stacking model demonstrates high prediction accuracy, providing an effective method for predicting the deformation of metal plates under double charges synchronous loading.
Research on heating characteristics of lithium battery under bullet impact
Authors: Zhang Song , Wu Yu , Tian Ye , Zheng Xu , Liu Yuan , Wang Haosheng , Wei Wei , He Liang
Published: December 2024

Lithium battery is the preferred power for modern weapons. Considering the high energetic density of Lithium battery, it is easy to trigger deflagration after impact by bullets, fragments, or other damage elements in the battlefield environment, thus causing the serious destruction on equipment. In this study, the heating characteristics and deflagration safety of 6Ah ternary Lithium battery under impact by 5.8mm bullet were systematically investigated. The deflagration of the lithium battery with full state of charge was trigger within 0.1s after impact, and the highest temperature was measured to be 750℃. Although the single impact failed to cause the deflagration of the lithium battery contained partial capacity, the maximum temperature increased by 92.5%, and the duration of heating decreased by 72%, respectively, with the state of charge increased from 50% to 75%. Finally, based on Joule’s law, a heating-up model of lithium battery after penetration was established, and the error between the calculation and the measured value was less than 5%.
Experimental Study on Damage of Ship Multi-cabin Protective Structure with Arc-shaped Supports Subjected to Underwater Contact Explosion
Authors: Guo T T , Zhang D Y , Chen J , Wang J , Zhang L P
Published: December 2024

Underwater contact explosion will cause serious damage to the multi-cabin protective structure (MPS) of large ships. In order to improve the protective performance of MPS, an effective way is to set arc-shaped supports behind the main protective wall to reduce the risk of damage. In order to explore the damage mechanism of multi-cabin protective structure with arc-shaped supports under contact explosion, a large-scale cabin model was designed and the underwater contact explosion test was carried out. The experimental data of the multi-cabin protective structure model after the test were obtained, such as model breach size, deformation and impact acceleration. The results show that underwater contact explosions will cause significant damage to the outer structure of the MPS, with main forms of damage including tearing of the outer plate, buckling of internal components, and production of fragments. The calculation method for breach size based on panel energy is in good agreement with the experimental results. Additionally, setting arc-shaped supports behind the main protective wall can significantly reduce the deformation of the main defensive wall and mitigate the risk of tensile failure at the upper and lower joints.
A neural network for the prediction of damage to reinforced cylindrical shells subjected to non-contact underwater explosions
Authors: Zhou K W , Ding S , Xie Y J , Shao Y , Zhang Z F
Published: December 2024

Explosion tests and numerical simulations are of great significance for the study of submarine and other underwater target damage characteristics. However, the cost of the real ship test is high, the implementation is difficult, and the time cost of the simulation calculation is high, which presents some difficulties in attempting to quickly assess the damage of underwater structures. Currently, the combination of machine learning and numerical simulation has become a more effective means of addressing the aforementioned issues. In this paper, the acoustic-structural arithmetic is employed to realise the non-contact underwater explosion simulation calculation of the reinforced cylindrical shell section. The maximum deflection of the reinforcement bar is extracted as the output parameter from the calculation results. The explosion distance, explosive equivalent, and the thickness of the reinforcement bar are taken as the input parameter. The prediction and analysis are carried out based on the back-propagation neural network algorithm of machine learning. The data generated by the neural network are processed and analysed for the error analysis. The processing and error analysis of the data generated by the neural network revealed that the neural network exhibited a superior prediction effect, establishing an accurate and efficient prediction model for the damage characteristics of underwater exploding cylindrical shells.
Computational Optimization of CFRP Strip Thickness for Enhanced Blast Mitigation in Structural Pipe Retrofitting
Authors: Saifi Farman , Javaid Mohd , Haleem Abid , Anas S. M.
Published: December 2024

Explosions, characterized by sudden energy releases and destructive shock waves, are increasingly frequent due to terrorism, industrial accidents, and infrastructure decay. These events pose serious risks to pipelines, causing leaks, disruptions in services, and environmental damage, highlighting the urgent need for robust mitigation strategies. The aim of this study is to explore the efficacy of CFRP strips in augmenting a pipe’s response to contact blast loads. Advanced 3D simulations of blast wave interactions with an empty pipe were conducted using computational fluid dynamics techniques. These simulations were complemented by comparative analyses using Abaqus, benchmarked against existing literature findings after rigorous validation. Subsequently, the research expanded to optimize the computational assessment of CFRP strip thicknesses for enhancing blast mitigation in structural pipe retrofitting. The authors systematically varied strip thicknesses from 0.15mm to 0.75mm in uniform increments of 0.15mm, evaluating their respective performances and comparing the results. Results showed that: CFRP strips significantly reduce pipe deformation under blast loading, with thicker strips, particularly at 0.75mm, demonstrating the highest effectiveness in enhancing blast resistance and minimizing severe damages.
Study on the critical velocity for initiation of a covered explosive by fragment impact
Authors: Yu Wanqian , Zhang Haijun , Guo Shang , Shu Qinghai
Published: December 2024

This study examines the critical velocity for initiating a covered explosive via fragment impact, crucial for enhancing ammunition safety and reliability. Using numerical simulation techniques, the initiation threshold and influencing factors under non-normal impact conditions are investigated, which are more relevant to battlefield scenarios. The Jacobs-Roslund formula for NTO based insensitive explosive is calibrated, which is applicable for both flat-nosed and standard conical-nosed fragments. To account for a large range of impact angles, a correction term is introduced, and the predicted values are in good agreement with the simulation results. The effects of fragment pitch, yaw, and charge curvature on the critical velocity are found to be minimal at impact angle not exceeding 25°.
Dynamic response of a Square Cabin under Blast Loading
Authors: Yang L Z , Wang J , Zuo Q W , Huang L Z
Published: December 2024

To investigate the dynamic response of square cabin under blast loading, three static explosion experiments were conducted on a small polyhedral structure square cabin. The TNT equivalent weights used were 1.04kg, 2.04kg, and 3.04kg, at distances of 1m, 0.8m, and 1.7m, respectively. The free-field overpressure sensor was employed to record the overpressure generated by the explosion, and the dynamic response of the square cabin structure under the blast loading was analyzed. Results show that the distribution of the square cabin skeleton and the quantity of equipment have a significant impact on the dynamic response of the square cabin. The research findings have important reference value for the application scope of square cabins on the battlefield.
Research on the sensitivity of various factors influencing the molding performance of PSC damage elements through orthogonal design
Authors: Hong Xiaowen , Xia Kailang , Shi Anshun , Wang Lujie , Qin Chao , Fan Xuefei , Zhao Hongyuan , Han Hongwei , Ge Yuanyuan
Published: December 2024

To investigate the forming characteristics of the damage element in a plane symmetric shaped charge structure, the geometric design of an oil perforating charge was undertaken. The shaping process of this damage element was then numerically simulated using LS-DYNA. By analyzing the factors influencing the molding performance of the PSC damage element, the orthogonal design method was employed to identify three key factors: groove wall thickness, groove width, and groove height. Additionally, five evaluation indices were established: head velocity, tail velocity, velocity gradient, length, and width of the damage element. The sensitivity of each factor to these evaluation indices was examined. The findings reveal that groove wall thickness and height are the primary factors influencing head velocity, tail velocity, head-tail velocity difference, and the length of the damage element. Except when the wall thickness is 0, where a monotonic increase is observed, the groove width is the primary determinant of the damage element’s width. Other evaluation indicators demonstrate contrasting trends relative to other factors. Ultimately, the combination parameter b4δ2h1, which exhibits superior cutting performance, was optimized.
Damage effect of composite sandwich structure under shock wave loading
Authors: Jianfei Li , Zejian Xu , Yan Liu
Published: December 2024

To investigate the damage effect of composite sandwich structure under shock wave loading, the damage experiment of composite sandwich structure under blast loading was carried out systematically. By studying the response process of the maximum deformation value and plastic deformation value of different composite sandwich structures under blast loading with the change of relative distance, a characterization method that measures the overall deformation of composite sandwich structure is proposed. The damage law of composite sandwich structure under blast loading and the failure mode of front and rear panels and core layer are obtained. Additionally, the causes of overall deformation and local failure of the front and rear panels, as well as the failure mechanism of the core layer, are analyzed. By analysing the relationship between the relative distance and the deformation value, combined with the damage degree of the composite sandwich structure under different relative distance, the results show that the relationship between the maximum deformation value of the sandwich structure and the scaled distance is monotonous. It is reasonable to characterize the damage degree and overall deformation of sandwich structure. Finally, based on the maximum deformation value of the composite sandwich structure, the damage criterion of the composite sandwich structure under blast loading is proposed by using the shock wave overpressure criterion.
Formation and Deflexion Characteristics of Explosively Formed Projectile with Eccentric Composite Shell Constraint
Authors: Tang Jing , Yu Rui , Liao Yu-gang , Wang Ya-jun , Du Hua-chi , Chen Xiao-hui
Published: December 2024

In this study, the influence of eccentric composite shell constraint to the formation and deflexion characteristics of EFP were studied. The laser high speed photography picture at typical moments of eccentric composite shell EFPs were taken. The influence of outer shell material parameters, height decline ratio (Hot/Hit), eccentric ratio (Ls/Ll) on the formation of EFP were analyzed by establishing geometric models based on Lagrangian-Eulerian (ALE) algorithm. Unaxisymmetric outer shell exhibits eccentricity in the pressure of reflected detonation wave. This made the pressure loading time of the liner at thinner side of outer shell decreased. Therefore, the eccentric change of detonation wave led to the formation of a deflected EFP. Eccentric composite shell constraint has significant influence of formation and deflexion characteristics of EFP. With the strength, density and Ls/Ll
of outer shell increase and the Hot/Hit
decrease, the velocity L/D and compactness of EFP increase, which is beneficial for forming a compact EFP. However, the displacement in X direction of ballistic and the deflexion angle of EFP increases, which will decline stability to the flight of EFP in air. The shorter the outer shell, the smaller impact on forming and deflexion of EFP, when Hot/Hit
of outer shell decreased to 0.4, the EFP characteristic parameter tended to stabilized. The research results can provide guidance for the asymmetric design of EFP.
Optimization of Micro-EFP charge structures based on PSO-SVM algorithm
Authors: Zhang Y M , Jiang J W , Wang S Y , Chen G J
Published: December 2024

To achieve a high-performance design of micro Explosive Formed Projectile (EFP) structures, a method based on the combination of the Particle Swarm Optimization (PSO) algorithm and Support Vector Machine (SVM) with numerical simulation technology is proposed for the optimization and design of EFP structures. The efficient optimization of the EFP structure is achieved by establishing the mapping relationship between the EFP structure and performance and using the PSO algorithm for parameter optimization. The results show that the optimal parameters of the structure are R
out/D
k=1.347, R
in/D
k=1.552, δ/D
k=0.045, σ/D
k=0.060, and N (L/D
k) =1.082. Under this optimization option, the EFP velocity is predicted to be 2362.6 m/s, and the numerical simulation results are 2385 m/s, with an error of only 0.95%. An effective optimization approach for the design of micro explosively formed projectiles is provided.
Prediction of FAE concentration based on Physics-Informed Neural Network
Authors: Zhang Zheng-qian , Lou Wen-zhong , Fu Sheng-hua , Wu Yi-zhe , Feng Heng-zhen
Published: December 2024

The dispersion concentration distribution of Fuel-Air Explosives (FAE) directly affects fuse warhead matching, thereby influencing the FAE weapon’s effectiveness. Therefore, real-time simulation of the concentration distribution during the fuel dispersion process is a key technology for the design of FAE weapon’s fuse warhead matching. This paper simplifies the FAE fuel dispersion process, constructs a model of the fuel dispersion process, establishes fuel diffusion control equations, designs the training process of Physics Informed Neural Networks (PINN) to fit the fuel diffusion process, and predicts of concentration of fuel clouds at different spatial coordinates at different times. The global relative error of the predicted values for the three physical fields is approximately 15% to 20%, providing a new method for simulating experiments on the dispersion process of FAE.
Deformation and damage of intermediate-thickness Mg6Gd3Y0.5Zr plate subjected to high-speed ballistic impact
Authors: Li J T , Hua J Y , Chai H W , Luo S N
Published: December 2024

Mg-rare earth (RE) alloys have been under rapid development as a novel class of lightest alloys. The ballistic performance of Mg-RE alloy plates, especially intermediate-thickness plates, is of particular interest for applied and basic studies, but rarely investigated. We investigate high-speed perforation of intermediate-thickness Mg6Gd3Y0.5Zr plate with ballistic experiment, microstructure characterization, and finite element simulation. The projectile is a stainless steel (SS304) sphere, the Mg6Gd3Y0.5Zr target plate is 20-mm thick, and the impact velocity is 1612 m s−1. High-speed photography captures target deformation and damage along with ejecta. Postmortem material characterizations indicate plastic deformation, localized shearing and spallation damages, and melting and re-solidification of the target. The finite element simulation can well reproduce the target behaviors and projectile residual velocity observed in the experiment. A multi-stage analysis on the histories of instantaneous projectile velocity and target rear face pressure reveals the transition of target deformation/damage modes during penetration/perforation. The projectile mainly decelerates during the front half of perforation, while spalling and plugging reduce the ballistic resistance to the projectile movement.
Investigation on spatial distribution characteristics of fragment damage field of composite warhead
Authors: Zhao Boxing , Li Ming , He Zheng , Zhang Jingbo
Published: December 2024

Most of the threats faced by air combat units consist of clusters of lightly armored targets. Fragmentation warhead technology plays a crucial role in effectively engaging such targets. This study focuses on investigating the power performance and spatial distribution characteristics of the fragmentation damage field generated by multifunctional composite warheads, aiming to meet the damage requirements for these specific targets. The impact of falling speed on the fragmentation damage field is analyzed through a combination of theoretical analysis and numerical simulation. Furthermore, this research examines how the shape and arrangement of prefabricated fragments, as well as the angle at which they are deployed, influence the fragmentation damage field under varying falling speeds. Additionally, a method is proposed to characterize the spatial distribution characteristics of the damage field based on fragment distribution along a cylindrical surface surrounding the detonation point. These research findings can serve as valuable references for enhancing fragment effectiveness and improving warhead design.
Study on cutting performance of CFRP by linear shaped charge
Authors: Rongqiang Liu , Rui Yu , Xuena Si , Ping Qu
Published: December 2024

Carbon Fiber-reinforced Polymer (CFRP) is widely used in weapons system because of their excellent specific strength, specific stiffness and fatigue resistance. Shaped charge cutting separation technology is the most widely used separation technology in aerospace due to its simple structure, high reliability, synchronization and other advantages. Through the cutting experiment of CFRP plate with different thickness, the cutting capacity threshold of the selected linear shaped charge is obtained as 15mm ∼ 16mm. Based on the experiment results, the finite element model of linear shaped charge cutting CFRP plate was established. The effects of different standoff, constraints and charge density on the cutting ability were calculated. The calculation results show that for the linear shaped charge in this paper, when the standoff is 3mm, the cutting performance is the best, and it can effectively cut through the CFRP plate with a thickness of 15mm; The designed 180mm × 100mm test plate can carry out the cutting experiment under the free boundary condition without affecting the cutting performance; The cutting depth of the linear shaped charge on the CFRP plate increase with the charge density, which exhibits a linear relationship. The research work in this paper can guide the selection and design of linear shaped charge for cutting and separating CFRP plate.
Numerical simulation on coupling effect and power performance of damage elements for multifunctional focusing warhead
Authors: Wang Tian , Wang Fang , Lan Yu-zhen
Published: December 2024

To further enhance the lethality and damage efficiency of the circumferential fragment, a multifunctional focusing warhead has been designed based on the traditional multifunctional warhead (cylindrical charge). To investigate the coupling relationship between fragment focusing and EFP (Explosively Formed Penetrator) forming in the multifunctional focusing warhead, the liner and focusing casing were transformed into the aluminum end cap and cylindrical casing as the control groups, and AUTODYN was employed for numerical simulation. To investigate the impact of charge curvature radius on the performance of damage elements in multifunctional focusing warhead, numerical simulations were conducted to analyze the EFP formation and fragment dispersion processes for cylindrical charged warhead and multifunctional focusing warheads with three different charge curvature radii. The results show that: (1) EFP forming does not significantly impact the performance of fragment focusing. Furthermore, when the charge curvature radius (R) is appropriately selected, the fragment focusing process does not adversely affect EFP forming. (2) As the curvature radius of the charge increases, the power performance of the multifunctional focusing warhead improves. The kinetic energy and tip speed of EFP also increase, while the length-diameter ratio of EFP decreases. Additionally, the average and maximum velocities of the prefabricated fragments increase, the fragment focusing band width narrows, and the fragment density within the focusing band increases. The numerical simulation results can serve as a reference for the design of multifunctional focusing warhead.
Comparison of mechanical response of head structure with different brain material models under impact
Authors: Haitao LU , Weibing LI , Qinglei DU
Published: December 2024

Brian material models and mechanical properties are very important for pressure evolution experiments and numerical simulations in head structure under impact. A simplified head structure with core-shell finite element model was established, and the motion, skull stress, skull deformation, and brain stress were numerically simulated with different soft tissue material models. The equivalence of the material model in stress propagation simulation was discussed. In the present work, it showed that when the head with impact velocity of 1m/s, the head structure rebound with a velocity of 0.6 m/s ∼ 0.8m/s, and occurred between 600μs and 1000μs due to different material models, at this time, the stress wave oscillation propagated in the skull underwent 3-5 repeated loads. The positive pressure on the impact side of brain tissue could reach 400kPa ∼ 800kPa, the negative pressure on the opposite side was between −150 kPa to −385kPa, the skull strain was between −1.8 ‰ to −3.7 ‰, and the skull stress was between 25.3MPa ∼ 41.2MPa. In a larger range of impact velocities, material models with strain rate effect have more advantages in stress wave transmission and pressure changing within the core-shell structure. The strain rate effect characterized only by creep and relaxation has limited effects on impact simulation, and directly introducing different strain rate mechanical property interpolation for hyperelastic model simulation is more effective.
A constitutive model for brittle rock subjected to dynamic loadings
Authors: Bai Z , Hu Y T , Li X , Yao H
Published: December 2024

The constitutive model of rock serves as the foundation for researching its mechanical responses under impact and explosion loads, and holds significant academic value and military significance. With the help of the basic solution to Eshelby’s matrix-inclusion problem and meso-damage mechanics, a new constitutive model was developed to describe the dynamic behaviour of brittle rock subjected to impact loadings. Brittle rock was considered here as heterogeneous solids composed of elastic solid matrix and imbedded penny-shaped microcracks. A rate-dependent constitutive relation, considering meso-structural damage mechanism of brittle rock, was derived based on the Ponte-Castaneda and Willis method. Further, micro-damage evolution equations with clear physical concept and fewer parameters were presented. In order to illustrate the predictive ability of the proposed model, comparisons are performed between the model predictions and experimental data from Split Hopkinson pressure bar tests on sandstone. The results show a generally good agreement, thus verifying its rationality and practicability.
The penetration crater characteristics of thick steel plate impacted by tungsten alloy projectiles
Authors: Cui Xin-yu , Luo Zi-qi , Huang Guang-yan , Hu Wen-long , Shi Xin-yi
Published: December 2024

The mild steel target plates impacted vertically by tungsten spherical projectiles with different initial velocities and projectile diameters were studied by ballistic experiments and numerical simulation. The macroscopic properties of the penetration crater were analyzed by the depth, diameter, and overall shape of the crater. The results show that crater diameter and depth increase as initial velocity or projectile diameter increases. With the increase in velocity, the deformation and erosion of tungsten projectiles significantly increased. Specific kinetic energy is used to normalize the velocity and size of the projectile, the expression of crater depth and diameter varying with specific kinetic energy is given, which accuracy R2 is 0.8. Based on THOR theory and experimental data, the accurate calculation model of penetration depth versus projectile mass, initial velocity, and the area of the contact was obtained, with an accuracy of R2 of 0.97.
Research and simulation study on the penetration behavior of Φ 30 mm armor-piercing bullets penetrating armored steel
Authors: Xuan Zhou , Rui Zhu , Ma Minghui , Gao Guangfa
Published: December 2024

To study the penetration behavior and ballistic characteristics of a Φ30mm tungsten alloy armor-piercing projectile penetrating homogeneous armor steel, penetration tests were conducted, and the penetration process was numerically simulated using LS-DYNA. The experimental results show that the presence of the conical section of the Φ30mm armor-piercing projectile forms a “saddle” shaped crater feature. The simulation results indicate that the penetration efficiency of the projectile and the incident velocity exhibit a quadratic function relationship. In the velocity range of 800-1200m/s, the kinetic energy consumed by the projectile for the same penetration depth is essentially the same, i.e., the lateral crater diameter is consistent at different speeds. Additionally, during the penetration process, the penetration depth as a function of time under different speeds also shows a quadratic relationship.