活性破片飞散特性及毁伤效应研究

为了掌握活性破片的空间飞散特性及毁伤效能,采用数值仿真与试验相结合的方法研究了某预制活性破片战斗部在爆炸作用下的飞散特性,得到了活性破片的空间分布和初始速度分布参数的有关数据,分析了活性破片对靶板的毁伤规律.结果表明:活性破片战斗部在起爆300 μs后,70％的活性破片速度分布在1 500～2 000 m/s;50％的...     

G45钢破片对中大口径弹体侵彻仿真分析北大核心

为了研究不同质量G45钢破片对中大口径弹药壳体侵彻效应,利用有限元分析软件ANSYS/LS-DYNA建立破片侵彻壳体模型。将弹药壳体通过等效公式换为Q235钢板,开展了在不同速度下,不同质量G45钢破片侵彻等效靶板Q235钢数值模拟仿真。仿真分析结果表明:相同质量下,G45钢破片撞击靶板侵彻深度与侵彻直径随着速度增加呈现递增趋势;得到了4.7 g,9.8 g小质量G45钢破片在800~1800 m/s速度范围内无法有效穿透中大口径弹体等效靶的结论;19.5 g G45钢破片侵彻20 mm的中大口径弹体等效靶的极限穿透速度范围在1200~1400 m/s之间。     

预制破片侵彻靶板临界跳飞角变化规律

为研究预制破片侵彻靶板的临界跳飞角变化规律,采用数值仿真的方法对预制破片侵彻靶板的临界跳飞角变化规律进行分析.利用LS-DYNA有限元仿真软件,建立了不同形状预制破片侵彻靶板的仿真模型,通过与试验结果相对比的方式验证了模型的可信性.分析了破片形状、破片形状比例系数、破片入射速度和靶板厚度对临界跳飞角的影响规律.分析结果表明:在相同条件下,破片临界跳飞角按照圆柱形、方形和球形预制破片的顺序依次减小,随着破片入射速度和破片形状比例系数的增大而增大,并在一定范围内随着靶板厚度的增加而减小.     

着靶速度对侵彻膨胀弹横向效应的影响

在建立弹靶模型的基础上,采用有限元软件LS-DYNA对装填尼龙的侵彻膨胀弹以不同着靶速度侵彻4340钢靶板的过程进行了数值模拟。结果表明:着靶速度对侵彻膨胀弹横向效应的产生有一定的影响。在PELE能够穿透靶板的前提下,随着着靶速度的进一步增加,横向效应的作用区域呈现出先减小后增大的趋势,而PELE穿透靶板后的速度损失越来越小;综合考虑横向效应的有效发挥和常规发射条件,PELE着靶速度的选取应选取800 m/s~1 300 m/s较为合适。     

陶瓷基复合装甲防12.7mm穿甲燃烧弹的靶试研究(Ⅲ)

基于对材料特性和防弹机理的认识,设计了由600D腈纶、无纺布、Al2O3陶瓷和高强PE材料构成的陶瓷基复合靶板,靶板防护面密度ρA为92 kg/m2,尺寸为300 mm×300 mm×35 mm,用现役12.7 mm穿甲燃烧弹考核了靶板防护能力,尤其是探讨了PE在背面不受约束情况时中弹后的行为.结果表明:靶板结构是可行的,可防住V25为810 m/s的现役12.7 mm穿甲燃烧弹,PE层有优良的防二次效应的性能,而靶板结构有较大的改进空间.在靶试和讨论分析的基础上,给出了靶板结构改进的设计方案.     

陶瓷基复合装甲防12.7mm穿甲燃烧弹的靶试研究（Ⅱ）

基于对材料特性和防弹机理的认识,设计了由（SiC＋Si）陶瓷、616装甲钢和高强PE材料构成的陶瓷基复合靶板,靶板防护面密度为118 kg/m2,尺寸为500 mm×500 mm×25 mm。利用现役12.7 mm穿甲燃烧弹考核靶板在6发弹打击下的防护能力,检验靶板设计思路。结果表明：靶板结构是可行的,可防住V25为818 m/s的现役12.7 mm穿甲燃烧弹。     

破片和冲击波复合作用下靶板毁伤仿真

为了研究目标在破片和冲击波复合作用下的毁伤情况,应用有限元动力分析软件ANSYS/LS-DYNA,建立破片和冲击波复合作用下靶板毁伤模型。将两者作用分开研究,重点研究破片对金属靶板毁伤形成沟槽的前提下冲击波的毁伤作用效果,即简化了模型又保证了仿真精度,弥补了以往只以穿孔等效破片毁伤效果的不足,增强了模型的通用性,为战斗部设计、毁伤评估和目标防护研究提供参考。     

破片模拟弹侵彻钢板的有限元分析

根据破片模拟弹侵彻钢板的实验研究,采用MSC.Dytran对破片模拟弹侵彻钢板的侵彻过程、侵彻特性、钢板的破坏模式以及弹体的侵彻速度、靶板的侵彻阻力进行了有限元分析,并将分析结果与实验结果进行了比较.分析结果表明,破片模拟弹冲击钢装甲的侵彻过程可大致分为初始接触、弹体侵入、剪切冲塞和穿甲破坏4个阶段.有限元分析的破片模拟弹侵彻特性及靶板破坏模式与实验观测结果有较好的一致性,在靶板破口的正面,与弹体平面凸缘两端接触的部分,变形以剪切为主,而与切削面接触的部分,以挤压变形为主;靶板破口背面为剪切冲塞破坏;有限元模拟的弹体剩余速度与实验结果吻合较好,弹体侵彻过程中弹靶作用界面的速度和侵彻速度近似呈线性变化.有限元分析结果还表明,采用适当的模型,有限元法能较好地模拟破片模拟弹侵彻钢板的侵彻过程、侵彻特性以及钢板的破坏模式.     

半穿甲舰炮弹药侵彻舰船靶板数值仿真研究

研究了舰炮半穿甲弹对舰船靶板侵彻能力,采用LS-DYNA有限元软件对美海军奥托·梅拉127 mm和76 mm舰炮弹药临界跳弹、打击甲板和侧舷靶板进行仿真,结果表明：以300 m/s速度打击15 mmE36钢板条件下,127 mm弹的临界跳角为9.5°,76 mm弹为29°;从甲板和侧舷攻击条件下,两弹均具备穿透多层舰船靶板的能力。舰炮弹药攻击舰船目标,可考虑适当延迟舰炮弹药起爆时间,在其进入内部重要舱室时引爆,提高对船体的毁伤效果。     

导弹战斗部破片杀伤试验误差分析

导弹战斗部设计、试验中的破片威力试验,一般采用静爆法,即将战斗部置于一定高度的托弹架上,根据战斗部的威力大小和测试项目布置靶板、靶网、传感器及各种测试仪器。战斗部的威力试验多采用一靶一网、多靶多网、使用测试仪等方法,但这些方法都不能准确反映战斗部的爆炸威力,不同品种、不同批次的战斗部的试验结果存在很大差异。如某型号导弹的试验中,各批破片数和破片初速均有一定差别,但同一批战斗部爆炸后的破片数量差高达98块,破片初速差竟达682m/s。因此,要反映战斗部威力试验的真实性,就有必要对战斗部静爆后的破片进行分析研究,得出可靠的试验数据,为设计、生产提供可靠的依据。     

Investigation on the spatial distribution characteristics of behind-armor debris formed by the perforation of EFP through steel target

The behind-armor debris (BAD) formed by the perforation of an EFP is the main damage factor for the secondary destruction to the behind-armor components. Aiming at investigating the BAD caused by EFP, flash X-ray radiography combined with an experimental witness plate test method was used, and the FEM-SPH adaptive conversion algorithm in LS-DYNA software was employed to model the perforation process. The simulation results of the debris cloud shape and number of debris were in good agreement with the flash X-ray radiographs and perforated holes on the witness plate, respectively. Three-dimensional numerical simulations of EFP's penetration under various impact conditions were conducted. The results show that, an ellipsoidal debris cloud, with the major-to-minor axis radio (a/b) smaller than that caused by shaped charge jets, was formed behind the target. With the increase of target thickness (h) and decrease of impact velocity (v₀) and obliquity (θ), the value of a/b decreases. The number of debris ejected from target is significantly higher than that from EFP. Based on the statistical analysis of the spatial distribution of the BAD, An engineering calculation model was established considering the influence of h, v₀ and θ. The model can with reasonable accuracy predict the quantity and velocity distribution characteristics of BAD formed by EFP.     

Analysis of the mass of behind-armor debris generated by RHA subjected to normal penetration of variable cross-section EFP

Analyzing the mass of behind-armor debris (BAD) generated by Rolled Homogeneous Armor (RHA) subjected to normal penetration of variable cross-section Explosively Formed Projectile (EFP) is the purpose of this paper. So theoretical analysis, numerical simulation and experimental data are combined to analyze the influence of variable cross-section characteristic on the time history of crater radius. Moreover the relationships between time history of crater radius (as well as mass of BAD) and the thickness of RHA (from 30 mm to 70 mm) and the impact velocity of EFP (1650 m/s to 1860 m/s) are also investigated. The results indicate that: 1) being compared to the variable cross-section characteristic is ignored, the theoretical time history of crater radius is in better agreement with the simulation results when the variable cross-section characteristic is considered; 2) being compared to the other three conditions of plug, the theoretical mass of BAD is in the best agreement with the simulation results when the shape of plug is frustum of a cone and the angle between generatrix and bottom is 45° and the axial length of mushroom is considered.     

Formation of explosively formed penetrator with fins and its flight characteristics

The ultimate goal of weapon system employing an explosively formed penetrator (EFP) is to defeat a target at the longest standoff. In order to do this, an EFP must be aerodynamically stable so as to strike the target at a small angle of obliquity, and the decay velocity per meter of EFP must be smaller at extended standoff. As the angle of attack increases, the penetration ability of EFP greatly reduces. The fins improve the EFP aeroballistic characteristics and decrease the flight drag of EFP as well. EFP with fins formed by three-point initiation is presented. The formation of EFP with fins is studied by LS-DYNA, and the aeroballistics is studied through experiment. The experimental results show that the decay velocity per meter of EFP with fins is much smaller than that of normal EFP, and the attitude angle steadily decreases.     

串联战斗部前后级作用关系数值模拟研究

利用Autodyn有限元软件采取三维数值仿真的方法,对串联战斗部前后级的作用关系开展研究。基于串联战斗部轴对称的特点,建立了1/2有限元仿真简化模型,通过设置前后级飞行速度0 m/s、100 m/s、200 m/s以及前后级间距10 mm、30 mm、50 mm,利用控制变量法,分析了前后级相对速度、前后级间距对随进子弹受力状态的影响规律。得出了随着前后级相对速度的增大或者前后级间距的减小,随进子弹各点的受力及速度降都会增大的变化规律。仿真结果可以为相关串联战斗部的优化设计提供参考。     

A study on the surface overpressure distribution and formation of a double curvature liner under a two-point initiation

The formation mechanism of an EFP(explosively formed projectile) using a double curvature liner under the overpressure effect generated by a regular oblique reflection was investigated in this paper.Based on the detonation wave propagation theory,the change of the incident angle of the detonation wave collision at different positions and the distribution area of the overpressure on the surface of the liner were calculated.Three-dimensional numerical simulations of the formation process of the EFP with tail as well as the ability to penetrate 45# steel were performed using LS-DYNA software,and the EFP ve-locity,the penetration ability,and the forming were assessed via experiments and x-ray photographs.The experimental results coincides with those of the simulations.Results indicate that the collision of the detonation wave was controlled to be a regular oblique reflection acting on the liner by setting the di-mensions of the unit charge and maintaining the pressure at the collision point region at more than 2.4 times the CJ detonation when the incident angle approached the critical angle.The distance from the liner midline to the boundary of the area within which the pressure ratio of the regular oblique reflection pressure to the CJ detonation pressure was greater than 2.5,2,and 1.5was approximately 0.66 mm,1.32 mm,and 3.3 mm,respectively.It is noted that pressure gradient caused the liner to turn inside out in the middle to form the head of the EFP and close the two tails of the EFP at approximately 120μs.The penetration depth of the EFP into a 45# steel target exceeded 30 mm,and there was radial expansion between the head and tail of the EFE increasing the penetration resistance of the EFP.Therefore,the structural size of the unit charge and the liner can be further optimized to reduce resistance to increase the penetration ability of the EFP.     

MEFP智能雷攻击坦克毁伤效能分析

以智能雷为研究对象,在建立智能雷扫描运动模型和命中毁伤模型的基础上,分析了MEFP智能雷攻击坦克的毁伤效能.通过建立攻击过程的蒙特卡洛模型,编制了智能雷攻击坦克目标的计算机仿真软件,计算了MEFP智能雷发射不同数目的EFP对坦克目标的毁伤概率.结果表明:MEFP智能雷攻击坦克目标的毁伤效能较高,可应用于对付大规模坦克装甲车辆的进攻和武装直升飞机的攻击.     

多爆炸成型弹丸性能参数灰关联分析

为了获得各参数对多爆炸成型弹丸毁伤性能的影响程度,以EFP速度和MEFP发散角为参考序列,以药型罩和装药参数为比较序列,运用灰关联理论对影响MEFP毁伤性能的参数进行了灰关联分析。在此基础上,应用灰关联分析结果完成了MEFP战斗部优化设计。结果表明:在较少样本空间前提下,采用灰关联理论可以分析获得影响多爆炸成型弹丸毁伤性能的各因素主次关系,而且经过优化后的MEFP战斗部,大大地提高了EFP的集聚性和毁伤性能。     

Experimental investigation on enhanced damage to fuel tanks by reactive projectiles impact

Enhanced damage to the full-filled fuel tank,impacted by the cold pressed and sintered PTFE/AL/W reactive material projectile(RMP)with a density of 7.8 g/cm3,is investigated experimentally and theoretically.The fuel tank is a rectangular structure,welded by six pieces of 2024 aluminum plate with a thickness of 6 mm,and filled with RP-3 aviation kerosene.Experimental results show that the kerosene is ignited by the RMP impact at a velocity above 1062 m/s,and a novel interior ignition phenomenon which is closely related to the rupture effect of the fuel tank is observed.However,the traditional steel projectile with the same mass and dimension requires a velocity up to 1649 m/s to ignite the kerosene.Based on the experimental results,the radial pressure field is considered to be the main reason for the shear failure of weld.For mechanism considerations,the chemical energy released by the RMP enhances the hydrodynamic ram(HRAM)effect and provides additional ignition sources inside the fuel tank,thereby enhancing both rupture and ignition effects.Moreover,to further understand the enhanced ignition effect of RMP,the reactive debris temperature inside the kerosene is analyzed theoretically.The initiated reactive debris with high temperature provides effective interior ignition sources to ignite the kerosene,resulting in the enhanced ignition of the kerosene.     

Effect of change of sand properties on travel distance of ricocheted debris

The debris from exploded buildings can ricochet after colliding with the ground, thus increasing the debris travel distance and danger from any associated impacts or collisions. To reduce this danger, the travel distance of ricocheted debris must be accurately predicted. This study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand medium. Direct shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the sand. Finite element analysis (FEA) was then applied to these variables to predict the speed and angle of the debris after ricochet. The FEA results were compared with results of low-speed ricochet experiments, which employed variable temperature and water content. The travel distance of the debris was calculated using MATLAB, via trajectory equations considering the drag coefficient. As the internal friction angle decreased, the shear stress decreased, leading to deeper penetration of the debris into the sand. As the loss of kinetic energy increased, the velocity and travel distance of the ricocheted debris decreased. Changes in the ricochet velocity and travel distance of the debris, according to changes in the internal friction angle, indicated that the debris was affected by the environment.     

Characteristics structure analysis on debris cloud in the hypervelocity impact of disk projectile on thin plate

In this paper, the gauge points setting is introduced in the SPH simulation to analyze the debris cloud structure generated by the hypervelocity impact of disk projectile on thin plate. Compared with the experiments, more detailed information of the debris cloud structure can be classified from the numerical simulation. However, due to the solitary dispersion and overlap display of the particles in the SPH simulation, accurate comparison between numerical and experimental results is difficult to be performed. To track the velocity and spatial distribution of the particles in the debris cloud induced from disk and plate, gauge points are locally set in the single-layer profile in the SPH model. By analyzing the gauge points’ spatial coordinate and velocity, the location and velocity of characteristic points in the debris cloud are determined. The boundary of debris cloud is achieved, as well as the fragments distribution outside the main structure of debris cloud.