Numerical Simulation of the Shaped Charge Jet Velocity Effected by Warhead Shell

The numerical simulation for the process of shaped charge jet produced with the shell of explosives is performed by means of the ANSYS/LS-DYNA 3D software. The effect of warhead shell on shaped charge jet velocity has been analyzed qualitatively in this paper. The numerical simulation results are creditable and in agreement well with that of the corresponding experiment. The research results show that the jet velocity of explosive with metal shell is higher than that without shell; when the shell thickness increases, jet＇ s head speed also increases; when the shell thickness increased to certain value, the jet velocity will not change any longer; with the same shell thickness, the bigger material density the higher jet＇s head velocity.

Numerical Simulation of High Performance Shaped Charge Penetrating Concrete Targets

Tandem warhead systems consist of a precursor shaped charge and a following kinetic energy projectile containing high explosive filling. This paper presents a numerical simulation analysis of the penetration forming and the process in which the shaped charge penetrated into concrete targets by using AUTODYN software. The shaped charge is consist of different materials, different standoff, different liner curvature and thickness. Parameters for the liner structure which can detemine ideal aperture and penetration depth are acquired. The simulation results are in agreement with them of the experiment.

Selection of shaped charges parameters for producing aluminum particles with velocities in the range of 2.5-16 km/s

Testing rocket and space technology objects in ground conditions for resistance to the impact of meteoroids and fragments of space debris can be carried out using shaped charges. To substantiate the design parameters of shaped charges that ensure the formation of aluminum particles in a wide velocity range(from 2.5 to 16 km/s), numerical modeling of the formation process was carried out within the framework of a two-dimensional axisymmetric problem of continuum mechanics using three different computing codes to increase the reliability of the results. The calculations consider shaped charges with a diameter of 20-100 mm with aluminum liners of various shapes. It is shown that the formation of particles with velocities close to the lower limit of the considered range is ensured by gently sloping segmental liners of degressive thickness. To form higher-velocity particles with velocities over 5 km/s, it is proposed to use combined liners, the jet-forming part of which has the shape of a hemisphere of constant thickness or the shape of a semi-ellipsoid or semi-superellipsoid of rotation of degressive thickness.

Influence of shaped charge structure parameters on the formation of linear explosively formed projectiles

The research of LEFP(linear explosive forming projectile)is of great value to the development of new warhead due to its excellent performance.To further improve the damage ability of the shaped charge warhead,a special shell overhanging structure was designed to increase the charge based on the traditional spherical charge,in which case the crushing energy of LEFP could be guaranteed.LS-DYNA was used to simulate different charge structures obtained by changing the number of detonation points,the length of shell platform,the radius of curvature and the thickness of liner.The RSM(response surface model)between the molding parameters of LEFP and the structural parameters of charge was established.Based on RSM model,the structure of shaped charge was optimized by using multi-objective genetic algorithm.Meanwhile,the formation process of jet was analyzed by pulsed X-ray photography.The results show that the velocity,length-diameter ratio and specific kinetic energy of the LEFP were closely related to the structural parameters of the shaped charge.After the optimization of charge structure,the forming effect and penetration ability of LEPP had been significantly improved.The experimental data of jet velocity and length were consistent with the numerical results,which verifies the reliability of the numerical results.

Simulation and Experimental Investigation of Jetting Penetrator Charge at Large Stand-off Distance

In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and spherical segment liner, are designed. The numerical simulation analysis of the formation, elongation and penetration processes of rod-like jet is conducted by using LS-DYNA software. And the penetrating test is carried out at long stand-off distance. The test results show that the rod-like jet formed by the optimized spherical segment liner can pierce through a 90mm thick 45# steel target at 20 charge diameters(CD) stand-off distance when the charge detonation mode is a central point initiation, and the penetration depth can be up to 1.6CD. It is concluded that, at 20 CD stand-off distance, the penetration performance of JPC with spherical segment liner is the best, that of truncated wide-angle liner takes second place, and that of spherical cone liner is the worst.

A comparative study for the impact performance of shaped charge JET on UHPC targets

With the development of two-stage munitions(a precursor shaped charge(SC)and a following kinetic energy projectile)to attack the hard concrete targets,as well as the increasing applications of ultra-high performance concrete(UHPC)in both civil and military protective structures,a comparative study on the impact performance of SC formed jet on UHPC target is performed experimentally and numerically at present.Firstly,a series of jet penetration/perforation test on the UHPC,45# steel and UHPC/45# steel composite targets are conducted.By assessing the penetration depth and borehole(crater and tunnel)diameter,the influences of target material and configuration as well as the standoff distance of SC on the impact performance of jet are experimentally discussed.Then,by adopting the 2 D multi-material Arbitrary Lagrange-Euler(ALE)algorithm,Fluid-Structure Interaction(FSI)method and erosion algorithm implemented in the finite element code LS-DYNA,the formation and impact performance of jet in the present test are well reproduced.Finally,based on the validated numerical algorithms,constitutive models and the corresponding parameters,the influences of target material(UHPC,NSC and 45# steel),standoff distance,target configuration(stacked and spaced)and weight efficiency on the impact performance of jet are further discussed.The derived conclusions could provide helpful references for evaluating the ballistic performance of jet and designing the protective structures.

Penetration and internal blast behavior of reactive liner enhanced shaped charge against concrete space

Penetration and internal blast behavior of reactive liner enhanced shaped charge against concrete space were investigated through experiments and simulations.The volume of the enclosed concrete space is about 15 m^(3).The reactive liner enhanced shaped charge utilizes reactive copper double-layered liner,which is composed of an inner copper liner and an outer reactive liner,while the reactive material liner is fabricated by PTFE/Al(Polytetrafluoroethylene/Aluminum)powders through cold-pressing and sintering.Static explosion experiments show that,compared with the shaped charge which utilizes copper liner,the penetration cavity diameter and spalling area of concrete by the novel shaped charge were enlarged to 2 times and 4 times,respectively.Meanwhile,the following reactive material had blast effect and produced significant overpressure inside the concrete closed space.Theoretical analysis indicates concrete strength and detonation pressure of reactive material both affect the penetration cavity diameter.To the blast behavior of reactive material inside the concrete space,developing TNT equivalence model and simulated on AUTODYN-3 D for analysis.Simulation results reproduced propagation process of the shock wave in concrete space,and revealed multi-peaks phenomenon of overpressure-time curves.Furthermore,the empirical relationship between the peak overpressure and relative distance for the shock wave of reactive material was proposed.

Bore-center annular shaped charges with different liner materials penetrating into steel targets

The bore-center annular shaped charge(BCASC)is a new type of shaped charge which can generate a larger-diameter hole in steel targets than classical shaped charges.In this paper,the influence of three liner materials,i.e.molybdenum,nickel and copper,on BCASC formation and penetrating into steel targets was investigated by experiment and numerical simulation.The simulation results were well consistent with the experimental results.This study showed that,at 0.50D standoff distance,the axial velocity of the molybdenum projectile was lower than that of the nickel and copper projectiles.The nickel and copper projectiles had almost the same head velocity.The absolute values of the radial velocity of the molybdenum projectile head was lower than that of the nickel and copper projectiles.However,at 0.75D standoff distance,the absolute values of the radial velocity of the molybdenum projectile head became much greater than that of the nickel and copper projectile heads.The projectile formed by BCASC with the molybdenum liner had the highest penetration depth of 61.5 mm,which was 10.0%and 21.3%higher than that generated by the copper and nickel projectiles.

Theoretical and numerical simulation study on jet formation and penetration of different liner structures driven by electromagnetic pressure

The use of a shaped liner driven by electromagnetic force is a new means of forming jets. To study the mechanism of jet formation driven by electromagnetic force, we considered the current skin effect and the characteristics of electromagnetic loading and established a coupling model of "ElectriceMagnetic eForce" and the theoretical model of jet formation under electromagnetic force. The jet formation and penetration of conical and trumpet liners have been calculated. Then, a numerical simulation of liner collapse under electromagnetic force, jet generation, and the stretching motion were performed using an ANSYS multiphysics processor. The calculated jet velocity, jet shape, and depth of penetration were consistent with the experimental results, with a relative error of less than 10%. In addition, we calculated the jet formation of different curvature trumpet liners driven by the same loading condition and obtained the influence rule of the curvature of the liner on jet formation. Results show that the theoretical model and the ANSYS multiphysics numerical method can effectively calculate the jet formation of liners driven by electromagnetic force, and in a certain range, the greater the curvature of the liner is, the greater the jet velocity is.

A numerical study on the disturbance of explosive reactive armors to jet penetration

The disturbance of flat and V-shaped sandwich reactive armor configurations to shaped-charge jet is studied by a numerical approach. The disturbing and cutting effects of the two reactive armor configurations to the jet are successfully captured. The predicted disturbance characteristics and patterns are in fairly good agreement with the X-ray photographic observations. The residual depth of penetration into a semiinfinitive homogeneous steel target behind the reactive armor is computed for a series of jet/armor parameters. For the flat configuration, it is demonstrated that the residual penetration depth is not significantly reduced for a normal impact while it is reduced up to 75% for an oblique impact. In comparison, the V-shaped configuration reduces the penetration depth of the jet to 90%, and it is observed that the penetration depth is not sensitive to the V-shaped angle.

Research on Matching Relationship Between Number of Initiation Points and Charge Diameter

For shaped charges,LS-DYNA software was adopted to explore the influence of number of initiation points on the penetrator formation numerically.Changed the number of initiation points from 4 to 36,the performance of penetrator under four different kinds of typical charge diameter was analyzed,and the effect of detonation wave pressure on the liner was discussed.The minimum number of initiation points to substitute for annular initiation was obtained for each of four warheads with different charge diameters,and the curve representing the relation between the number of initiation points and charge diameter was found out also by using polynomial fitting.The simulation result provides a reference for the design of multimode warhead.

基于AGEP-DNN的水下聚能装药比冲量预测模型

聚能装药比冲量是表征水下爆炸中冲击波对目标破坏作用的重要参数。为实现水下聚能装药比冲量智能预测,提出一种自适应基因表达式编程(adaptive gene expression programming, AGEP)优化深度神经网络(deep neural network, DNN)的聚能装药比冲量预测模型(AGEP-DNN)。考虑装药结构与比冲量数值之间的复杂非线性关系,通过AUTODYN软件建立有限元模型,对水下爆炸过程进行仿真,采用经验公式验证仿真数据的有效性;基于仿真实验数据,设计AGEP算法优化DNN超参数,构建AGEP-DNN模型,对比冲量进行智能预测。实验结果显示,AGEP-DNN聚能装药比冲量预测模型在9种对比智能预测模型中具有最优的预测精度。

烤燃条件下JEO聚能装药战斗部泄压结构研究

为提高JEO聚能装药战斗部的热安全性,对烤燃条件下JEO聚能装药战斗部的泄压结构进行研究。建立考虑热分解压力对烤燃过程影响的炸药烤燃多相流组分输送模型。设计多点测温-测压实验,对JEO炸药烤燃过程中的温度-压力变化特性进行研究并对模型相关参数进行校核,对聚能装药结构下JEO炸药的热分解过程进行数值模拟,获得不同升温速率下炸药温度、固相体积分数的变化规律,并确定了该结构下炸药的点火位置、点火压力。针对JEO炸药点火后的燃烧过程,引入泄压延迟时间,建立考虑泄压结构的炸药压力增长模型,确定该结构下JEO炸药的临界泄压面积,以热分解数值模拟中获得的点火位置和点火压力为初始条件,计算获得不同装药点火位置对炸药内部压力变化的影响规律。根据临界泄压面积、点火位置、炸药中的压力增长规律,确定侧壁泄压孔面积大小和端面药型罩压螺尺寸,设计适合该结构下JEO炸药的泄压孔-药型罩推出组合泄压结构。针对采用该泄压结构的JEO聚能装药战斗部进行快速烤燃和慢速烤燃实验,验证泄压结构的有效性。研究结果表明:随着升温速率的降低,JEO装药聚能战斗部的点火时间随之延长,点火位置由装药表面移动至装药中心;随着点火位置和泄压结构之间距离的增加,点火延迟时间增大,聚能装药战斗部内部压力峰值随之增加,战斗部的反应烈度随之增加。

不同组合式聚能战斗部对水下目标的毁伤研究

为研究不同组合药型罩聚能型鱼雷战斗部对含水复合结构的穿透性能,建立了聚能装药侵彻含水复合结构的数值计算模型,分析了射流成型过程和穿靶过程。结果表明:圆柱-球缺组合罩相比于其他2种组合药型罩对含水复合结构的穿透性能更好,对后效靶造成的穿深最大。圆柱-球缺组合罩形成的射流长度相比于其他2种组合药型罩分别长10.4%和28.9%,头部速度分别高20.6%和54.3%。侵彻含水复合结构时,圆柱-球缺组合罩形成的水下空腔、水介质径向扩展速度均最小,所以在侵彻含水复合结构后得以保留最大的剩余动能,从而对后效靶造成的穿深最大。合理匹配圆柱-球缺药型罩圆柱部直径d和高度h可提升其对含水复合结构的穿透能力,当d=22 mm、h=16 mm时,圆柱-球缺组合罩可对后效靶取得最大穿深411 mm。结论可为聚能型鱼雷战斗部的组合药型罩选择提供参考。

不同药型罩结构对环形EFP成型及侵彻性能影响的数值模拟

为研究不同药型罩结构对环形EFP成型及侵彻性能的影响,利用LS-DYNA动力学分析软件对环形药型罩进行了数值模拟与对比分析。首先设计了环锥形罩、环半球罩和环亚半球罩3种典型药型罩结构,数值模拟发现环亚半球罩成型的环形EFP成型效果最好、侵彻效果最优,但成型过程环形EFP的姿态仍然具有向外偏斜的趋势。进一步采用变壁厚设计思路,对环亚半球罩进行了优化设计,当壁厚偏移量取0.15时,成型的环形EFP不仅具有优良的飞行稳定性,还具有最好的成型和侵彻效果。本研究对于环形药型罩结构设计具有一定的指导意义。

圆柱-双锥结合药型罩结构参数对侵彻性能的影响规律

为提高聚能破甲战斗部的毁伤能力,设计了一种圆柱-双锥结合药型罩。用数值模拟方法,通过对该药型罩的正交优化设计,研究了药型罩圆柱部直径d、高度h、上锥角α、下锥角β对射流头部速度和侵彻深度的影响。研究结果表明,上锥角和圆柱部直径分别是影响射流头部速度和侵彻深度的主要因素。因此,在优化设计中得到了兼顾射流速度和侵彻深度的最佳药型罩结构:d=8 mm、h=12 mm、α=36°和β=56°时,射流头部速度为8 667 m/s,侵彻深度达到173.7 mm。优化设计的研究结果具有一定的实际工程指导意义,可为聚能破甲战斗部的性能提升提供有效的设计方案。

近距爆炸装药形状对板架结构的损伤规律研究

为了研究近距爆炸时柱形装药长径比对板架结构变形损伤的影响规律,以某典型缩比板架结构作为研究对象,采用经实验验证的有限元模型,分析了5种不同长径比装药爆炸对板架变形损伤的影响,并对比分析了药柱与板架夹角为0°和90°两种情形的区别。研究结果表明:随着装药长径比的增大,夹角为90°情况下冲击波反射超压和冲量逐渐减小,夹角0°情况下冲击波反射超压和冲量逐渐增大,高压区逐渐从装药轴线方向到径向方向移动;板架的残余位移与装药质量近似满足线性关系,装药长径比增大时,夹角为90°时靶板的残余位移逐渐减小,夹角为0°时位移逐渐增大;基于板架中心点最大残余位移D,拟合得到了药柱轴线与靶板表面夹角为90°和0°时的轴向等效形状因子β_(1)和径向等效因子β_(2),当比例距离在0.4~0.7 m/kg^(1/3)范围内时,预测误差小于15%,能较好的预估不同装药长径比下板架的中心点残余位移,获取结构的损伤水平。

辅助药型罩对射流性能的影响

辅助药型罩结构能实现超聚能效应,有效地提高破甲威力。为了研究辅助药型罩对射流性能的影响,设计一种辅助型双锥药型罩,通过AUTODYN数值模拟的方法,分析辅助药型罩材料和结构对射流性能的影响。结果表明,当主药型罩采用铜,辅助药型罩材料为钨时,射流综合性能优异;设计主药型罩大锥角70°,小锥角40°,壁厚2 mm,辅助药型罩厚度在2~6 mm时,随着厚度增加,射流性能改善,6 mm时射流性能最佳,辅助药型罩直径在20~28 mm时,26 mm时射流综合性能最佳。

水平岩层单孔切缝聚能爆破效果影响因素研究

隧道水平岩层聚能爆破效果的影响因素众多,且各因素对爆生裂隙扩展特性的影响尚不明确。针对这一问题,采用有限元建立单孔聚能爆破模型,验证其正确性,开展了水平岩层单孔正交数值模拟试验分析,通过研究揭示各因素对单孔聚能爆破效果的影响规律。结果表明,对水平岩层单孔聚能爆破效果影响程度最大的是不耦合系数,聚能爆破下岩体内水平爆生裂隙扩展长度、贯穿充填节理长度、非聚能方向围岩损伤范围,都与不耦合系数呈负相关,并综合考虑不耦合系数对爆破效果的影响给出了其建议值。

近自由液面聚能战斗部水下爆炸威力场

聚能战斗部反舰武器因其高效毁伤能力而受到重视,然而现阶段对其在近自由液面的威力场研究较少。为此,结合聚能战斗部对水下靶板毁伤试验结果,建立与之相对应的数值仿真模型,利用任意拉格朗日欧拉(arbitrary Lagrange-Euler,ALE)算法模拟了金属射流形成和毁伤靶板全过程。同时,在验证模型算法有效性的基础上,通过系列工况设置,研究了小锥角聚能战斗部在近自由液面爆炸冲击波和射流特点。研究结果表明,近自由面聚能战斗部水下爆炸压力具有不对称性;自由液面对金属射流无明显影响,但受自由液面处反射的稀疏波影响,近自由液面冲击波压力下降,出现空化区域。