bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study on the Effect of Buffer Layer on the Explosive Drive of Reactive Fragment
Authors: Peng Jun , Liu Wei , Liang Zheng-feng , Guo Hong-fu
Published: June 2023

In order to study the influence of the buffer layer on the explosive drive of the reactive fragment, for the reactive fragment warhead of the same structure, the warhead static explosion test and the break-through target test method were used to test the fragment integrity and the fragment integrity of the reactive fragment warhead of the reactive fragment warhead with several different thickness silicone rubber buffer layers. The initial velocity of the fragment was measured, and its integrity and the variation law of the initial velocity were analyzed. The results show that with the increase of the thickness of the buffer layer, the integrity of the reactive fragments increases. When the thickness of the buffer layer is 2 mm, the fragment integrity rate is zero, and when the thickness of the buffer layer is greater than 8 mm, the integrity rate is greater than 0.85. The difference in the initial velocity of the warhead of the same reactive fragment is small, mainly because with the increase of the thickness of the buffer layer, the initial velocity of the fragment decreases mainly because the loading ratio of the warhead decreases; the buffer layer has a significant effect on reducing the initial velocity of the reactive fragment, and k=0.83 can be used The modified Gurney formula was used to estimate the initial velocity of the reactive fragments of the silicone rubber buffer layer.
Dynamic response behavior of PTFE/Al/oxide reactive materials
Authors: Yuan Ying , Sun Tao , Wang Haifu
Published: June 2023

PTFE/Al, as a kind of typical reactive material with a high energy density and impact-induced reaction characteristics, has attracted extensive attention. Three kinds of PTFE/Al/oxide materials were designed and fabricated by introducing CuO, Fe2O3, and MoO3 into PTFE/Al, and their dynamic mechanical responses were studied by SHPB experiments. The results showed that the sample cracked undergoing high strain rate compression, the metal particles peeled off from the matrix on the microstructure, and many PTFE filaments formed on both ends of the crack. PTFE/Al/oxide presents typical elastoplastic characteristics with strain rates ranging from 3000 s−1 to 7000 s−1. With the increase of strain rate, the failure stress and failure strain of the three materials increased, showing a significant strain rate strengthening effect. Among them, PTFE/Al/CuO has the highest failure stress and strain. The mechanism analysis shows that the porosity of Fe2O3 and the agglomeration effect of MoO3 lead to the number of initial pores increasing in the sample, and these pores easily trigger the propagation of cracks
Penetration enhanced behaviour of reactive fragment impacting medium-thickness plate
Authors: Xiang J A , Sun T , Liu A X , Guo H G , Wang H F
Published: June 2023

The medium-thickness plate penetration enhanced behavior of coupled kinetic energy and chemical energy of reactive fragment was investigated. A series of penetration experiments were conducted. After the experiments, the High-speed photography images and blackening at front plate were compared. The results show that the enhancement behavior of reactive fragment penetrating is related to the intensity of deflagration at front plate. Division of deflagration zones of reactive fragment impacting at front plate is proposed, combine dynamic model of reactive fragment penetrating medium-thickness plate, reveal the enhancement mechanism of reactive fragment penetrating medium-thickness plate below ballistic limit velocity.
Influence of initiation manner on forming characteristics of reactive material jet
Authors: Shi D F , Hu Die , Cai Y Q
Published: June 2023

The influence of different initiation manners on the forming features of reactive material jets was investigated using the AUTODYN-3D simulation software. The numerical simulation findings demonstrate that, as compared to center point initiation, annular multi-point initiation greatly improves the velocity of the reactive material jet head created, but the expansion impact is more noticeable during the jet generating process. At the head and axis of the jet, there are noticeable low density zones (density less than 1.2 g/ cm3) and high temperature zones (temperature greater than 1000 K) with annular multi-point initiation. This is due to the superposition of several detonation waves, which raises the detonation pressure pressing on the reactive material liner, resulting in faster liner crushing. Furthermore, when the number of initiation points and the distance between initiation positions increases, the range of low density and high temperature regions extends, reducing the reactive material jet’s penetration capabilities.
The flow behavior and constitutive equation of (Al3Ti+Al2O3)/2024Al composites during hot compression
Authors: Yang L , Chao Z L , Zhao Z H , Jiang L T , Chen G Q , Wu G H , Tong H
Published: June 2023

In this study, Al3Ti and nano-Al2O3 co-reinforced aluminum matrix composites were prepared in situ autogenously using TiO2 and Al alloys as raw materials. The high-temperature compression properties of the composites were tested at temperatures ranging from 300 to 500 °C and strain rates ranging from 0.0014 s−1 to 0.42 s−1. Excellent high-temperature properties were demonstrated due to the presence of a large amount of Al3Ti and nano-Al2O3 high-temperature phases in the composites. The peak compressive stress of (Al3Ti+Al2O3)/2024Al composites gradually decreases with increasing temperature and increases with increasing strain rate. The study also calculated the deformation activation energy of the composites and the intrinsic structure model during hot compression. This is a guideline for obtaining the material thermal processing conditions of new composites with excellent high-temperature properties.
Research on High-performance PEEK Composites
Authors: Juncong Liu , Shuhu Li , Aiyun Liu , Wenfang Xing , Junyan Li , Ping Li , Lei Shi
Published: June 2023

Polyetheretherketone (PEEK) has excellent comprehensive properties, but compared with traditional materials, it has many disadvantages, such as small modulus of Elasticity, small impact force, high melting point and so on. In order to improve the properties of PEEK composites, this paper summarized the improvement schemes of the mechanical properties, electrical conductivity, friction resistance, high temperature resistance and other properties of PEEK and its composites. The properties of PEEK composites filled with carbon nano-materials, fibers and whiskers were reviewed, and the research progress of modified PEEK composites in recent years was introduced, the aim is to improve the comprehensive properties of composite materials by adding a small amount of materials. And the development situation and the law were summarized from some certain degree. In the end, the development direction and trend of PEEK composites were prospected.
Effect of Ce on the microstructure and property of Sn0.7Cu solder
Authors: Yue Fan , Wei Wei , Lei Zhang , Xiucai Yang , Dashun Zhang
Published: June 2023

The effect of Ce multi-addition on wettability and microstructure of Sn-0.7Cu solder was investigated. The results indicated that the multi-addition of Ce could greatly improve the wettability of solder and refine the microstructure of solder matrix. The optimal property of solder was obtained when the addition of Ce reached 0.1 wt.%. With the increasing of Ce addition, black phase appeared and tend to be accumulated in the solder matrix. EDS results indicated that the composition of black phase contained varies elements including Sn, Cu, Ni, and Ce. Compared with the previous research results of solder with excessive Ce addition, no obviously Sn-Nd phase was observed while a small amount of Ga2Nd phase appeared in the solder matrix.
Properties and Defence Applications of Carbon Nanotubes
Authors: Guo Hui-li , Zhang Qing-xian , Liu Yan-ping , Zhao Dong-kui
Published: June 2023

Properties and defence applications of carbon nanotubes are discussed in the paper. Carbon nanotubes are important emerging materials, showing diverse unique and interesting properties, such as optical, electronic, magnetic and mechanical properties, at the same time high chemical reactivity as well, due to their quantum confinement effects, more important, these properties are tunable in some extend. Lots of applications such as strength-enhanced structure materials, radar-absorbing structure, armor, body armor, wearable thermoelectric devices, smart textiles, water purification, warfare agent sensors and flat panel display, and so on, can be found using carbon nanotubes.
Microfluidic preparation and thermal properties of HMX@PDA@MO
Authors: Yu J , Yao E , Xu S , Wang Y
Published: June 2023

Metal oxides can effectively promote the thermal decomposition of energetic materials. However, the traditional physical mixing process has potential safety hazards and cannot achieve uniform and stable coating. To address this issue, this study provides adhesion sites for metal oxides through the rough coating formed by polydopamine on the surface of HMX, which improves the coating stability. Taking advantage of the safety and efficient mixing of microfluidic technology, HMX@PDA@MO samples with good dispersion were prepared. The samples were characterized by SEM-EDS, XRD and DSC. The XRD results demonstrate the successful preparation of HMX@PDA@CuO and HMX@PDA@PbO samples. SEM-EDS images show that polydopamine forms a rough coating on the surface of HMX, and the increase in the total flow rate is beneficial to enhance the dispersion of metal oxides. The DSC data showed that the addition of 3% and 20% CuO advanced the thermal decomposition temperature and apparent activation energy of HMX@PDA by 0.3K, 40.13 kJ·mol−1 and 2K, 108.83 kJ·mol−1, respectively, PbO is 0.1K, 111.94 kJ·mol−1, and 4.5K, 205.02 kJ·mol−1. It shows that the increase of metal oxide content will promote thermal decomposition. For HMX, PbO has better catalytic activity than CuO. PbO has better catalytic activity than CuO for HMX.
Design theory and anti-ballistic effect simulation of dual phase hybrid functionally graded ceramic composite armor
Authors: Li Nan , Shen Zhiwei , Tao Zhiguo
Published: June 2023

Functional gradient structure design is one way to improve the anti-ballistic performance of ceramic composite armors. In this paper, the design theory of dual phase hybrid functionally graded ceramics is established. Through the finite element simulation of the anti-ballistic behaviour, three structural effects of dual phase hybrid functionally graded ceramics composite armor are studied: monolithic ceramics (MC), unidirectional functionally graded ceramics (UFGC) and bidirectional functionally graded ceramics (BFGC). The ceramics structure of composite armor is optimized. The simulation results of the optimized structure of unidirectional and bidirectional functionally graded ceramics are better than that of monolithic ceramics, and the weight is lighter. This research can provide theoretical support for the design of functionally graded ceramic composite armor.
A numerical calculation method of laser illumination starting time suitable for air-to-ground missiles
Authors: Zou Ruping , Chen Shichao , Li Peng , Duan Chenlu , Liu Ming , Chen Yun
Published: June 2023

Focusing on the problem of the precise determination of laser illumination starting time for air-to-ground missiles (AGMs), a numerical calculation method based on multidimensional polynomial fitting is proposed in this paper. The presented method takes various factors including temperature, altitude, and platform velocity into consideration. Influence by the parameters is delivered step by step through feature points-based polynomial fitting, and high-precision laser illumination starting time can be achieved. Helicopter-borne AGM flight data have verified the effectiveness of the proposed method.
A novel image quality evaluation method based on two-dimensional information entropy
Authors: yi Liu , Zili Huang , Fangyuan Yu , Guochuan Lin , jing Zeng , mengmeng Ma , li Zhan , xiang Zhang
Published: June 2023

In image transmission, with the consideration of system parameters, such as bandwidth, transmission delay and power consumption, the image compression coding is often used to reduce the amount of transmitted data. The formation mechanism of block effect in H.264 coding is analyzed. Taking H.264 coding as an example, the spatial domain image enhancement processing is adopted in the paper to obtain the two-dimensional information entropy covering the gray correlation and image edge feature information in adjacent spatial domain. By referring to the two-dimensional information entropy evaluation value of original and coded image, the image quality evaluation result is consistent with PSNR method used in common situations. Compared with the traditional PSNR evaluation method, the two-dimensional information entropy evaluation method only refers to the two-dimensional information entropy evaluation value of the original image, and the amount of data required is very low. Therefor, it is more suitable for the engineering implementation of real-time image quality evaluation in image transmission system. At the same time, with the edge feature information of the image used in the two-dimensional information entropy, the entropy method is closer to the actual feeling of human eyes than PSNR method.
Lightweight-YOLOv5s for the camouflaged personnel detection in the woodland
Authors: Xu Bin , Wang Congqing , Liu Yang , Zhou Yongjun
Published: June 2023

Unmanned aerial vehicles(UAVs) technology and target detection technology are increasingly integrated. However, the target detection networks are cumbersome and complex, and it is hard to directly deploy these networks on the UAVs. To address this problem, a Lightweight-YOLOv5s which can be applied to the UAVs is proposed to detect the camouflaged personnel in the woodland. Depthwise separable convolutions are added to the YOLOv5s for reducing the parameters and computational effort. Then a new channel pruning method based on Batch Normalization(BN) layer scaling factor with adaptive sparsity training is proposed for network compression, which can balance the compression ratio and accuracy of the detection. The pruned network is then fine-tuned to detect the camouflaged personnel. In addition, a special dataset is built for the camouflaged personnel detection in the woodland. The quantitative results on this dataset prove that the proposed Lightweight-YOLOv5s greatly improve the YOLOv5s. Parameters from 7.06M to 1.86M, floating point operations from 16.4G to 9.9G and inference time from 8.16ms to 7.06ms. Besides, mAP of the Lightweight-YOLOv5s is 0.83, which shows the excellent detection performance of the proposed method.
An unsupervised aerial tracking method of camouflaged targets in complex environments
Authors: Liu Yang , Wang Cong-qing , Xu Bin , Zhou Yongjun
Published: June 2023

With the widespread use of UAVs and the development of various technologies related to computer vision, much attention has been devoted to UAV-based target tracking. For the task of tracking camouflaged people in complex environments, there is a shortage of annotated datasets and poor backbone feature extraction network capabilities, which will cause tracking drift and tracking lag. To achieve unsupervised UAV target tracking under unsupervised conditions, a new target tracking model has been designed. First, we roughly detect moving targets using a camouflaged segmentation network, and then apply dynamic programming to generate smooth candidate boxes. Secondly, a deeper convolutional neural network is designed for feature extraction to replace the original backbone network, and the residual structure is modified to ensure tracking effectiveness. Extensive comparative experiments have shown that the proposed unsupervised method performs the task of UAV target tracking well.
Low-light image enhancement based on Retinex theory for beam-splitting prism system
Authors: Liu Haozhou , Zhang Wenwen , He Weiji
Published: June 2023

The existing color image enhancement methods are utilized for the most part to directly improve the color image that is obtained through the use of a Bayer array camera, whereas the color image that is obtained through the use of a prism camera is the result of the fusion of three primary color images that have been collected independently. As a result, a method for enhancing color photographs based on three images of primary colors that have a low level of light has been proposed. In this paper, we first transfer RGB to HSV space for image enhancement. In the V channel, we use guided filtering combined with improved SSR method to better preserve edge information. Then the S channel is adjusted adaptively to make the image look more natural. Finally, the image is transferred from HSV space back to RGB space. Compared with other traditional methods, our method achieves better results in PSNR, SSIM and NIQE, and has less computational complexity.
Unsupervised Terahertz Image Restoration Based on CycleGan
Authors: Su Zhipeng , Zhang Yixiong , Qi Feng , Shi Jianghong
Published: June 2023

Terahertz (THz) is considered as one of the key technologies for sixth generation communications, military, medical imaging and industrial inspection. THz images are susceptible to degradation due to system noise and point spread functions during transmission. The existing deep learning methods use ground truth and input images for supervised training that can recover THz images very well. But it’s difficult to obtain labeled THz data in practical application. In this paper, we propose an attentional adversarial cycle generation network for THz image restoration (CycleTHz) based on CycleGan to address this problem. The CycleTHz generates clean images firstly by an attention-guided generation network and then discriminates the quality of the generators by an attention discriminator. In addition, RGB color loss is used for image channels for constraint. To the best of our knowledge, this is the first THz dataset to be trained using an unsupervised approach. Extensive experiments show that the proposed method improves the PSNR and SSIM by 43.4% and 101.7% compared with CycleGan, which is a benchmark method for the unsupervised development in THz image restoration. The code is available at https://github.com/hellogry/UnsupervisedCycleTHz
The Simulation of the Terahertz Modulator by CMOS Process
Authors: Zhang Chenyu , Hu Nairui , Liu Zhaoyang
Published: June 2023

The paper introduced the simulation of the terahertz modulator in complementary metal-oxide-semiconductor (CMOS) process. The modulator is composed of a metal split-ring resonator (SRR), CMOS, semiconductor dielectric layer and silicon substrate. The modulator can make different electromagnetic response to the transmitted terahertz wave between the connection state and the disconnection state of the gap in the SRR, which could be achieved by connecting CMOS in the gap. At 0.31THz, the simulation results show that the amplitude modulation depth of the modulator reached 28.8%. When the simulation keeped the modulator system in resonating state, the transmission coefficient was about 0.0018, while the conductive had reached 0.2895. If the design can pass the experimental verification in the future, it can make some references for further exploration of the high-speed and high modulation depth of the terahertz amplitude modulator.
Influence of Rock Layer Thickness on the Penetration Resistance of a Composite Target
Authors: Xiaojing Zhang , Wenjin Yao , Wenbin Li , Xintao Zhu , Hongxin Huang
Published: June 2023

To describe the influence of rock thickness on the penetration resistance of rock-concrete composite targets, a three-dimensional model was simulated using the nonlinear dynamic simulation software LS-DYNA. The penetration of four composite targets with rock-concrete thicknesses of 10-20, 20-20 cm, 30-20 and 40-20 cm by a projectile at a target angle of 75 degrees is investigated in this study. A damage cloud diagram of the target plate is obtained, and the curves of penetration speed and overload in the X and Y directions of the projectile with time are analysed. During penetration, the rock and concrete layers tend to restrain each other from destroying the target’s back and surface, and the projectile directly enters the tunnel area of the concrete layer from the tunnel area of the rock layer. When the ratio of rock thickness to shot length is less than 1.5, the attitude of the projectile after penetrating the composite target is relatively stable.
Research on Ballistic limit model for a typical 93W ball-Q235 steel plate projectile target system
Authors: Xuncheng Guo , Dongjiang Zhang , Mingxue Zhou , Shushan Wang , Lei Zhang
Published: June 2023

A representative and most commonly used ballistic target system consisting of a 93W ball and Q235 steel plate is investigated for its ballistic limit fast calculation engineering model. The basic data on the material of the projectile target system was obtained through quasi-static compression tests on the mechanical properties of 93W ball and Q235 steel plate materials. Using a Φ12.7mm ballistic gun and the ten shot v50 ballistic limit method, tests were carried out with 93W balls positively penetrating Q235 steel target plates and v
50 was obtained for 3g of 93W balls penetrating 6mm and 8mm thick Q235 steel plates respectively. Based on the Autodyn platform, a numerical simulation model of a 93W ball intruding through a Q235 steel target plate was established and the accuracy of the simulation model was verified using test data. On this basis, the range was extended to obtain v
50 for a total of 34 working conditions with 93W ball masses between 1 and 6g and Q235 steel target plate thicknesses between 2 and 12mm, and the v
50 engineering calculation model for 93W ball intrusion into Q235 steel plate was obtained by multiple linear regression. Comparative analysis with other representative v
50 engineering models shows that the resulting v
50 calculation model has a greater range of applicable speeds, higher accuracy and greater practicality. The results of the research can provide basic methods and tools for the design of warhead power, target protection, and the assessment of the destructive effectiveness of weapons and ammunition.
Thickness Equivalent Method of 921A and Q235 Steel Plate Based on the Similarity of Projectile Penetration Residual Velocity
Authors: Han L , Jiang H Y
Published: June 2023

The penetration judgment of the projectile to the target is vital to evaluate its damage ability. Based on the similarity of projectile penetration residual velocity, the thickness equivalent model of plates with different materials is proposed in this paper. Simulation parameters are validated by physical experiments. Then a series of numerical simulations are carried out on 30CrMnSiNi2A projectiles penetrating 921A and Q235 steel target plates. Results show that with the increase of the plate thickness, the projectile residual velocity decays linearly, while the slope depends on the incident velocities. Simultaneously, the residual velocity conforms to a logarithmic growth as the mass of the projectile increases. Finally, the thickness equivalent relationship between 921A and Q235 steel plate is established by using the ratio of the material strength, the incident angle and the projectile shape coefficient. The proposed model can provide a reference to the general projectile penetration analysis.
Numerical Simulation Research on Characteristics of Underwater Explosive Bubble Jet in Offshore Water
Authors: Chen Si , Qin Jian , Meng Xiangyao , Wen Yanbo , Huang Ruiyuan
Published: June 2023

Underwater explosions have always been a hot topic in the field of ship protection. When explosives explode in offshore waters, the influence of seabed and structural boundaries on shock wave propagation and bubble pulsation will become more complicated. In this paper, a numerical simulation study of the underwater explosion between a deformable seabed and a rigid boundary is carried out. Firstly, the ABAQUS software was used to establish a numerical model by using the CEL method. The seabed was regarded as a heavier fluid, and the density ratio of the seabed and water was used to describe the characteristics of the seabed. The validity of the model was verified by comparison with experiments. Then, a series of numerical simulations were carried out by adjust the position of the explosive, the thickness of water medium layer, and the density of the seabed. The results show that: when the position of the explosive is close to the seabed and the rigid boundary, the bubble pulsation period is longer. The water jet and the pulsating pressure of the bubbles have a strong impact on the structure when the explosive is located near to 1 times the theoretical maximum radius of the bubble. As the depth of the water decreases, it can be observed that the bubbles transform from “ellipsoid” to “nipple-like”, and finally tear into upper and lower halves. When the thickness of water medium layer is 1 times the theoretical maximum radius of the bubble, the incident pressure waveforms of the bubble pulsation and the water jet near the structure are chaotic, which is caused by the “tear” phenomenon of the bubble. As the density of the seabed increases, the depth of the intrusion of the bubbles into the seabed becomes smaller and the shape of the bubbles becomes flatter. The research results of this paper can provide reference for the protection design of ships.
Numerical Simulation of Anti-penetration Performance of Ceramic/Aramid Fiber/PE-UHMW Composite Armor
Authors: Fuqiang Li , Jingru Huang , Runhua Liu , Liang Zhao , Zheng Wang
Published: June 2023

In order to study the anti-penetration performance of ceramic/aramid fiber/PE-UHMW composite armor, based on the FEM-SPH coupling algorithm, SPH model is established for brittle ceramic materials to simulate the formation of ceramic cone, crack propagation and fragmentation splash process. The failure mode on aramid fiber and PE-UHMW is analyzed. The influence of different projectile velocities and impact points on the anti-penetration performance of the composite armor are analyzed. The results show that the ceramic panel in the composite armor absorbs part of the kinetic energy of the projectile through passivation, fragmentation of the projectile and panel fragmentation. The failure modes of aramid laminates are mainly delamination shear failure, bending deformation and fiber tensile fracture. The failure modes of PE-UHMW laminates are mainly compression shear failure of the projectile facing surface and small-scale delamination tensile failure of the back layer fiber. When the projectile velocity is less than the ballistic limit, the energy absorption of composite armor and the maximum deformation of back plate increase with the increase of projectile velocity. When the projectile velocity is greater than the ballistic limit, the energy absorption rate of composite armor begins to decrease. When the impact point of the projectile is located at the edge of the ceramic block, the ceramic can’t effectively consume the kinetic energy of the projectile, and the composite armor presents bad performance.
Prediction of Spatial Peak Overpressure Profile of Air Blast Shocks Using Multiple Linear Regression and Artificial Neural Network
Authors: Xi H. Z. , Kong D. R. , Peng Y. Q. , Zhang S. M. , Shi Q , Le G. G.
Published: June 2023

The shock peak overpressure yielded by energetic materials in the near-earth explosion causes damage to people and property. In the literature, several works have reported the effectiveness in obtaining the peak overpressure in the near field by numerical simulation, real tests, and empirical calculations. However, several issues are associated with the above methods, such as the time-consuming of a complex simulation, the difficulties in placing sensors in an obstacle block site, and the limited scope of applications for empirical equations. At present, there is no single model that can rapidly predict the spatial distribution of shock peak overpressure with ground reflection. In this regard, this paper aims to solve the problem of shock propagation in a large-scale space and obtain a model that can predict a wide range of spatial distribution of peak overpressure in the near-earth air blast simply and quickly. This work uses AUTODYN-2D to obtain the peak overpressure of the cylindrical charge explosion in the air near earth. The peak overpressure from the numerical models agrees with the empirical equations and the real blast results. On this basis, the multiple linear regression (MLR) and the optimal error back-propagation artificial neural network (ANN) models are tried and constructed with three geometric parameters as the input under a typical environment. The input parameters are the straight line scaled distance (SLSD), the vertical scaled distance (VSD), and the scaled height of burst (SHOB), respectively. The prediction results of the MLR and ANN models are verified and compared on the test set. Results show that the ANN model with the geometric parameters as the input is better than the MLR model in predicting the air blast peak overpressure. The former takes no more than 0.2s to compute 1441 sets of inputs, which provides a quick reference for predicting spatial peak overpressure in a large-scale shock wave of the air blast.
Numerical simulation and optimization design of the landmine blast protection package
Authors: Li Nan , Li Jishan , Wang Wanpeng
Published: June 2023

The finite element model is established based on the bench test of the landmine blast protection package. The effect of the air gap between the landmine blast protection package and the base plate as well as the stiffness of the package on the deformation of the base plate are investigated. Aluminum sandwich landmine blast protection packages are designed and the effects on the deformation suppression of the base plate are studied using the finite element model. The results show that the air gap is not conducive to the deformation suppression of the base plate. Increasing the stiffness of the package is of benefit to the deformation suppression of the base plate, however, it is necessary to consider the influence of the corresponding increase in thickness of the package on the possible increase in the base plate deformation. The scheme, composed of one piece of 2024-T3 aluminum plate and two pieces of 7mm armored steel, is the best solution among the six aluminum sandwich schemes.
Study of linear shaped charge (LSC) jet penetrating layered targets
Authors: Xu Bin , Liu-Chun mei
Published: June 2023

This paper presents the results of an experimental and numerical study conducted to investigate the mechanism of penetration of linear shaped charges (LSCs) into double layered targets. A type of LSC causing less collateral damage in terms of jet residues was studied. The LSC consisted of a linear liner and case with the depth to diameter aspect ratio of 2.0. Anti-theft doors and spaced steel plates were used to represent double layered targets. The anti-theft door and the equivalent targets were penetrated with little jet residues behind the exit crater. The experiments were simulated using the commercially available software AutoDYN as a 2-D planer symmetry FEM model of the LSC penetrating a double layered target. An Eulerian mesh was used to model the LSCs whilst the double layered target was modelled using a Lagrangian mesh. A fully coupled algorithm was used for two different meshes. The data from the experiments (the shape of the breach and jet residues) were used to validate the numerical model. The validated numerical model was used to gain insights into the penetrating mechanisms of the LSC. The numerical results indicated that the penetration mechanisms of the two layers target were different. The first layer was penetrated by a continuous jet typical of a high-speed jet whereas the second layer was perforated by both a jet tip and slug characterized by a low-impact velocity projectile (slug).
Numerical simulation of penetration behavior of RHA target with biconical liner
Authors: Liu C Z , Zhou S , He S , Xiang J Y
Published: June 2023

The AUTODYN-2D simulation software was used to study the jet formation of single-cone and biconical shaped charge liner and the damage influence on the RHA target. The numerical simulation results show that compared with the typical single-cone shaped charge structure, the jet head formed by the biconical liner is faster and has better penetration performance on the RHA target. On this basis, the influence of standoff, liner cone angle and line thickness on the penetration characteristics of RHA target under biconical shaped charge was studied. The simulation results show that when the standoff increases from 2.0CD to 3.0CD, the penetration depth increases gradually. When the upper cone angle is 30° and the lower cone angle increases from 40° to 60°, the penetration depth of the formed jet to the target decreases gradually. When the liner thickness increases from 5mm to 6mm, the penetration depth is obviously improved.
Response behaviour and microstructural evolution of Ti6321 titanium alloy under air explosion
Authors: Yan Zhiwei , Wang Lin , Ning Zixuan , Li Yanxing
Published: June 2023

The titanium alloy has been used for marine structrural components because of the excellent properties. The response of material under explosion when in the service process should be carried out. In this research, the explosion test of the Ti6321 titanium of three different structure is executed to study the microstructure evolution. The optical microscope is used for observing the microstructure and adiabatic shear bands (ASB). The electron backscatter diffraction method is used to study the microstructure and recrystallization of the biamodal structural target under different charges. The result shows that the deformation of the target become larger with the increase of the charge. The ASBs have been observed in the target, demonstrating that it is an important reason for the damage. The twinning mechanism comes into play a role in the deformation of the material while dislocations become difficult to satisfy. The grain size of the bimodal material decrease with the increase of the charge. The deformed grains of the target start to recover and recrystallize at high temperature due to shock waves of explosion.
Flexural strength and ballistic performance of vinyl ester resin/aramid fiber composites toughened by graphene nanosheets
Authors: Dong Bin , Wei Rubin , Wang Xiaowei , Fu Siwei , Zhang Wenting , Zhai Wen
Published: June 2023

The fiber reinforced polymer (FRP) armor composites are kinds of composite materials specially designed and manufactured to prevent the penetration of high-speed bullets and fragments. The FRP composites are commonly composed of reinforcing fibers, resin matrix and their interfacial structures. The vinyl ester resin (VER) is a kind of thermosetting resin commonly applied in the field of high performance bulletproof composites. However, the VER has the problem of insufficient toughness after curing, which seriously limits its application. In this research, the graphene nanosheets were homogeneously dispersed into VER matrix by ultrasonic-assisted dispersing process. The effects of graphene content on the mechanical and dynamic mechanical thermal properties of VER castings were investigated. The graphene-toughened VER/aramid fiber (AF) composites were prepared by hand layup-vacuum bag molding process. The influences of graphene content on the flexural strength and ballistic resistance of VER/AF composites were investigated. The results showed that the tensile strength, elongation at break, flexural strength and non-notch impact strength of VER casting filled with 0.1 wt.% graphene increased by 5.6%, 27.6%, 11.7% and 90.5%, respectively, compared with those of unfilled VER casting. The glass transition temperature Tg of VER casting gradually increased with the increase of graphene content. The hand layup-vacuum bag molding process effectively reduced the filtering effect of the fiber fabrics on graphene sheets. When the amount of graphene was 0.1 wt.%, the flexural strength of VER/AF composite was increased by 34.2%. Due to the improvement of fracture toughness of the resin matrix, the ballistic limit velocity V
50 and specific energy absorption of the VER/AF composites were both improved.
Experimental research on impact adiabatic relationship of 30CrMnSiNi2A steel
Authors: Yan Huadong , Hu Bing , Zhang Qidong , Qu Xiaoting
Published: June 2023

As an ultra-high strength steel, 30CrMnSiNi2A steel has good plasticity, toughness and fatigue resistance, and it has been widely used in components that withstand explosion and dynamic shock loads. Therefore, the mechanical behavior of 30CrMnSiNi2A steel under strong impact load is the focus of attention. In this paper, the flyer impact experiment of 30CrMnSiNi2A steel is carried out in the pressure range of 0~20 GPa by a one-stage light air gun, and the impact adiabatic relationship of 30CrMnSiNi2A steel is studied. The Hugoniot pressure and Hugoniot temperature of 30CrMnSiNi2A steel were obtained by fitting the valid experimental data. The research results provide a reference for the application of 30CrMnSiNi2A steel in the field of explosion and impact.
Parameters identification and forward rushing motion optimization for a big calibre soft recoil gun
Authors: Zhao W , Hou B L
Published: June 2023

Aiming to deal with the problem of the forward rushing velocity reduction caused by the increase of the firing angle of the soft recoil gun, a dynamical model of the soft recoil gun during forward rushing motion is established, and an improved immune clone selection algorithm is proposed. The vaccination strategy is introduced into the immune clone selection algorithm to improve the convergence speed. The random crossover strategy and elite learning mechanism enhances the ability to escape from the local extremes and avoids premature algorithmic maturity. Based on the introduction of the above three strategies, the convergence speed and calculation accuracy of the algorithm are improved, and the convergence time is greatly shortened which saves a lot of time for subsequent parameter identification and optimization calculations. By using the improved immune clone selection algorithm, the unknown parameters in the dynamical model can be identified accurately and quickly. Then, the parameters are used to correct the dynamical model which increase the accuracy of the optimization results. Finally, the algorithm is used to optimize the initial pressure of the gas spring in the forward momentum generator, so as to ensure that different firing angles have the same maximum forward rushing velocity, which improves the stability of the forward rushing motion and the reliability of the firing. Through the optimization calculation, the pressure variation curve of the gas spring with the change of the firing angle is finally determined. The forward rushing velocity is stable at 5.65m/s with different firing angles.
Influence of High-temperature Environment on Cook-off Characteristics of Modular Charge
Authors: Qian H Y , Yu Y G
Published: June 2023

In order to study the heating process of the modular charge loaded into the chamber after the continuous firing of the large caliber gun in the high-temperature environment, a 2D transient cook-off model of the modular charge retained in the chamber was established with cook-off method. When the ambient temperature is 323K and the critical temperature of the inner wall of the gun chamber is 443K, the wall temperature distribution of the gun is solved after 2 rounds/min of continuous firing. Taking this as the initial temperature condition, the cook-off process of the modular charge in the chamber is numerically simulated, and then the cook-off-odd characteristics of the modular charge in the high-temperature environment are analyzed. The results show that after 33 rounds of continuous firing at 2 rounds/min at 323K ambient temperature, the temperature of the inner wall of the gun chamber reaches 442.7K, and the modular charge would have a cook-off response after 107.5s after loading into the chamber, and the response temperature is 483.5K. The initial response position of the modular charge is located at the inner wall of the upper right corner of the module cartridge. The consistency between numerical calculation and experimental results shows that the model could analyze the cook-off problem of modular charge in bore well.
Experimental Study and Numerical Calculation of Projectile Dynamic Engraving Process
Authors: Yang M , Zhang X W
Published: June 2023

The high temperature and pressure gas in the combustion chamber pushes the projectile towards the muzzle during the firing of the gun. The projectile belt is squeezed and deformed by the forcing cone. In order to study the dynamic engraving characteristics of the projectile, a short-barrel gun launcher was designed for experimental research. The projectile dynamics and projectile base pressure curves during the engraving process were obtained. Based on the experimental loading conditions, the J-C elastic-plastic model was used to numerically simulate the dynamic engraving process of the copper elastic belt. The deformation process of the elastic belt and the change characteristics of the resistance after the elastic were studied and the intrusion displacement obtained by the numerical calculation was compared with the experimental results and the results are consistent.
Design and experiment of broadband electric field sensor for high-power sub-nanosecond pulse measurements
Authors: Jiang Dan , Su Yun , Wang Yajie , Jin Zhaoxin
Published: June 2023

This paper briefly introduces the structure and working principle of the electric field sensor. And a conductive electric field sensor for measuring sub-nanosecond voltage pulse is designed. The sensor consists of coaxial transition section and integrated electric field probe. N-type connector and SMA connector are selected for input/direct output port and coupling output port respectively. The equivalent antenna area of electric field sensor measured by vector network analyzer is about 0.035cm2, and the 3dB bandwidth is more than 5GHz. The results show that the sensor can accurately measure the time-domain voltage pulse produced by the sub-nanosecond solid-state sources.
Engineering calculation and analysis of aerodynamic heating for hypersonic rocket sled
Authors: Hu Bing , Qu Xiaoting , Fu Liang , Yan Huadong
Published: June 2023

Aerodynamic heating and temperature distribution are one of the problems that must be considered in the design of hypersonic rocket sled. In order to evaluate the aerodynamic heating environment of hypersonic rocket sled, the typical monorail rocket sled with cone cylinder combination is taken as the research object, the aerodynamic heating calculation methods such as Modified Newton Theory, Reynolds Analogy Theory, Reference Enthalpy Method and Fourier’s Law of Heat Conduction are used, and the temperature variation law of rocket sled conical surface under Mach 5 and Mach 7 ballistic is calculated and compared with the measured data in the literature to verify the accuracy of the calculation program. The engineering calculation method can provide a reliable design basis for the rocket sled structure and thermal protection configuration. The analysis of the calculation results shows that when the speed of hypersonic rocket sled exceeds Mach 5, serious thermal heating problem cannot be ignored, and protective measures such as thermal protective materials and helium channel should be taken.
A Fuzzy Controller for PFN Trigger Time Sequence in Electromagnetic Railgun System
Authors: Zhang Huayi , Tang Yilin
Published: June 2023

For the electromagnetic launch system, how to realize the wide pulse, fast rise, and small fluctuation of pulse forming network output current is a core problem. A trigger time sequence control method based on fuzzy theory for the pulse forming network is proposed in this paper. First, circuit models of pulse forming unit, pulse forming network, and electromagnetic rail launcher is established. Second, a fuzzy trigger time sequence controller model for pulse forming network is designed by using Simulink. Third, fixed time sequence discharge tests consisting of 20 pulsed forming units on the linear simulation load are carried out to verify the accuracy of the simulation model. Finally, discharge tests on the linear simulation load and launch tests on the electromagnetic railgun are carried out to verify the precision of the fuzzy controller output respectively. The results show that the designed fuzzy trigger time sequence controller can obtain the ideal trigger time sequence, which demonstrates the pragmatic and reliability of fuzzy control algorithm.
Design and test of a compact capacitor-based energy storage pulsed power module with high repetitive discharge frequency
Authors: Wang Zhang-fei , Liu Jian , Feng Bo , Li Bao-ming
Published: June 2023

Advance in electromagnetic launch have put forward higher requirements for the pulsed power supply(PPS). A capacitive PPS for electromagnetic launcher has been constructed in NJUST recently with a basic cell of 220kJ energy storage, which has a good scalability. Design of integrated 220kJ pulsed power unit (PFU) was demonstrated in the paper. To meet the requirement of compact structure of PPS, the device design and system layout are considered and combined with simulation to optimize the magnetic field distribution in the constrained space. In order to achieve the function of continuous discharge, the reliability of thermal management system, control system and safety protection system are focused on. System description was presented in the paper. A series of experiments were conducted to verify the performance of the module. The results show that the PFU shows good reliability in 10 consecutive burst-shot tests. Due to the modular setup of this pulse formation network, it can be extended to a larger-scale pulse forming network. Flexible current pulse shapes can be formed by controlling the charging voltage and the trigger time of the PFU.
Numerical simulation analysis of armature force under muzzle arc
Authors: Gao Yuan , Zhang Ya-zhou , Li Yan-ming , Zhao Bin
Published: June 2023

the metal component arc plasma at the muzzle of railgun is simulated by magneto-hydro-dynamic(MHD) model, and the flow field under the interaction between armature and muzzle arc jet during the movement of muzzle position is modeled and simulated. The sheath model is considered in the plasma simulation near armature during the movement. According to the calculation results of the MHD model, the transient current curve through the armature is analyzed, and based on the results, the transient electromagnetic field simulation of the armature-arc-rail system is realized. The results show that during the launch process, the drastic change of armature current will produce eddy current in the armature, resulting in the component of electromagnetic force opposite to the launch direction.