尖头弹丸撞击下金属靶板弹道极限的两种工程模型

研究了圆锥形头和卵形头刚性弹垂直撞击塑性金属靶板扩孔冲塞型和延性扩孔型穿孔模式,考虑靶板背面自由边界的影响,提出两种两阶段工程分析模型,得到最小穿透能量的解析解。由球形空腔膨胀理论和两阶段总耗能最小确定第一阶段的侵彻深度,由功能原理和圆柱形空腔膨胀理论计算第一阶段侵彻扩孔耗能,延性扩孔型第二阶段耗能近似按Taylor扩孔理论计算,扩孔冲塞型第二阶段耗能考虑了加速塞块和剪断塞块所损耗的能量。与铝合金和装甲钢靶板弹道试验数据比较表明,本文两阶段模型的计算结果与试验结果吻合较好。     

椭圆截面截卵形刚性弹体正贯穿加筋板能量耗散分析

为获得椭圆截面截卵形刚性弹体正贯穿加筋板的剩余速度，根据椭圆截面弹体贯穿靶板的破坏特征，认为贯穿过程中靶板的能量耗散方式主要为塞块剪切变形功与塞块动能、扩孔塑性变形功、花瓣动力功、花瓣弯曲变形功、靶板整体凹陷变形功、加强筋侧向凹陷变形功。推导了每种能量计算方法，计算中定量考虑了靶板扩孔、花瓣弯曲、凹陷变形的应变率效应。根据能量守恒关系，得到了椭圆截面弹体剩余速度和弹道极限速度预测公式。并通过实验结果对模型进行了验证。结果表明:考虑靶板应变硬化、应变率效应的贯穿模型可以准确预测弹体剩余速度；随着椭圆截面弹体长短轴之比的增大，靶板的弹道极限速度近似线性增大；长短轴之比小于3时，加筋板的主要耗能为花瓣弯曲变形能、整体凹陷变形能。     

球形破片侵彻下钢/铝复合靶板的失效模式与吸能机理

为研究复合靶板自身结构对其防护性能的影响，针对面密度相同的两层钢/铝、三层钢/铝/钢爆炸复合板以及均质钢板，采用系列弹道实验和LS-DYNA3D非线性有限元程序分析了复合靶板在球形破片侵彻作用下的失效模式和吸能机理，讨论了靶板层数、厚度和界面结合情况对失效模式的影响。研究结果表明:较其他因素而言，界面结合状态对靶板失效模式的影响最明显，当界面结合良好时，各层靶板均发生剪切冲塞破坏，而当结合界面发生拉伸失效时，较薄的背板以延性扩孔破坏为主；随着靶板总厚度的增大，靶板更易发生剪切冲塞破坏；当靶板的面密度和总厚度分别相等时，三层复合靶板的防护性能优于双层靶板。     

刚性弹体斜侵彻贯穿混凝土靶的姿态偏转理论模型

为描述刚性弹体斜侵彻贯穿混凝土靶的弹体姿态变化，针对已有贯穿模型存在的问题，在斜侵彻贯穿过程中考虑了弹体转动惯量对姿态偏转的影响，根据弹体贯穿靶板后的成孔特性重新假设了背靶面崩落块形状，并在弹体贯穿出靶的剪切冲塞阶段引入了弹体姿态二次偏转机制，从而建立了刚性弹体斜侵彻贯穿混凝土靶的姿态偏转理论模型，同时给出了混凝土薄靶、中厚靶和厚靶的分类方法。多种侵彻状态的理论模型计算结果均与实验测量结果吻合较好，表明本文理论模型可有效预估弹体斜侵彻贯穿混凝土靶的弹体出靶姿态。     

基于耗能模型的超空泡射弹水下侵彻鱼雷等效关系研究

超空泡射弹是水下防御技术的研究热点之一。水下毁伤试验费用大,成本高,陆上等效试验是一种可能的替代方案。为此需要获得水下超空泡射弹侵彻条件下目标与相关材料的等效关系。以MK48-5鱼雷为对象,构建由壳体和14个关键部件组成的典型鱼雷结构模型。考虑水介质对侵彻的影响,将水下超空泡射弹侵彻鱼雷的过程分为两个阶段（a. 射弹侵彻水介质和鱼雷壳体,b. 射弹侵彻鱼雷内部关键部件）;建立水介质耗能模型和靶板耗能模型;依据极限穿透速度等效原则和能量等效原则,分别得出两个阶段目标和等效靶之间的靶板厚度关系;为了获得射弹垂直命中鱼雷不同方向及不同工况毁伤效果,需要对纵向侵彻全雷和横向侵彻鱼雷战雷段、控制段、燃料舱和后舱雷尾4个典型舱段分别进行研究;并基于此建立了水下侵彻和不同工况条件下射弹侵彻鱼雷的多层等效靶模型。     

弹头部形状对侵彻影响的数值模拟研究

采用MOCL(Markoncellline)分界面跟踪算法,用二维多流体网格法的欧拉程序,对卵型头和平头动能弹侵彻混凝土平靶的过程进行了数值模拟研究,给出了侵彻过程中的物质变形情况及对应的破坏区域。基于计算结果,分析了弹头部形状对侵彻的影响。得出卵形头弹体的穿透过程是一种刺穿性模式,对靶孔周围破坏区域呈现出两头大、中间小的M型;而平头弹体则是一种挤凿性模式,对靶孔周围破坏区域较小。穿透同样的靶板,平头弹的侵彻耗能比卵形头弹侵彻耗能大,剩余速度小。     

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对穿甲弹准定常侵彻半无限厚靶 板的问题，提出了一个考虑应变率效应的包括带有蘑菇头的未碎弹体、弹的破碎及扩孔区、 靶的破坏和扩孔区的简化侵彻模型. 通过侵彻过程中简化模型各部分的力学守恒定律，得到 了侵彻问题的简化常微分方程组，并以分析和数值计算相结合的方法分析了弹、靶强度的应 变率效应及弹破碎应变的应变率效应对侵彻效果的影响. 数值计算结果跟实验结果对比基本 一致.     

WFeNiMo高熵合金动态力学行为及侵彻性能研究

为了探究不同应变速率下WFeNiMo高熵合金的变形行为和侵彻性能, 采用万能材料试验机、分离式霍普金森压杆开展了高熵合金的静动态力学性能试验, 讨论了其在不同应变速率下变形特征微观机制. 基于弹道枪试验平台开展了高熵合金与典型钨合金(93W-4.9Ni-2.1Fe,wt%)破片对有限厚钢靶侵彻作用性能试验研究, 分析了两种合金破片侵彻作用过程与靶板破坏特征、侵彻穿孔能量消耗与撞击速度间的关系. 结果表明: 高熵合金、钨合金材料屈服强度与应变率呈正相关, 且在相同的应变率下高熵合金具有更高的屈服强度; 随着应变率的提高, 高熵合金由脆性断裂、韧脆混合的准解理断裂发展至具有黏着特性的破碎变形模式; 高熵合金具有较强的局部绝热变形能力, 在侵彻薄钢靶时体现出较高的剪切敏感性; 相同撞击速度下, 高熵合金破片穿靶消耗的能量低于钨合金破片, 对于薄钢靶具有更强的侵彻穿透能力. 高熵合金具有优异的力学性能和侵彻能力, 在高速撞击薄靶板时除了传统的剪切冲塞作用还具有一定的能量释放特性, 在预制破片上有较好的应用前景.      

DYNAMIC MECHANICAL BEHAVIOR AND PENETRATION PERFORMANCE OF WFeNiMo HIGH-ENTROPY ALLOY 1)

为了探究不同应变速率下WFeNiMo高熵合金的变形行为和侵彻性能, 采用万能材料试验机、分离式霍普金森压杆开展了高熵合金的静动态力学性能试验, 讨论了其在不同应变速率下变形特征微观机制. 基于弹道枪试验平台开展了高熵合金与典型钨合金(93W-4.9Ni-2.1Fe,wt%)破片对有限厚钢靶侵彻作用性能试验研究, 分析了两种合金破片侵彻作用过程与靶板破坏特征、侵彻穿孔能量消耗与撞击速度间的关系. 结果表明: 高熵合金、钨合金材料屈服强度与应变率呈正相关, 且在相同的应变率下高熵合金具有更高的屈服强度; 随着应变率的提高, 高熵合金由脆性断裂、韧脆混合的准解理断裂发展至具有黏着特性的破碎变形模式; 高熵合金具有较强的局部绝热变形能力, 在侵彻薄钢靶时体现出较高的剪切敏感性; 相同撞击速度下, 高熵合金破片穿靶消耗的能量低于钨合金破片, 对于薄钢靶具有更强的侵彻穿透能力. 高熵合金具有优异的力学性能和侵彻能力, 在高速撞击薄靶板时除了传统的剪切冲塞作用还具有一定的能量释放特性, 在预制破片上有较好的应用前景.     

EFP对有限厚靶板侵彻过程及后效研究

描述了爆炸成型弹丸(explosive formed projectile,EFP)对有限厚靶板的侵彻过程,建立了计算EFP对有限厚靶板侵彻过程参数的一维分析模型。基于该模型编制了程序代码,对EFP侵彻有限厚靶板的后效参量及极限穿透速度进行了计算,并和试验结果进行了比较。证明该模型能较准确地对EFP侵彻有限厚靶板后效参量进行计算。     

细长尖头刚性弹对金属靶板的斜侵彻/穿甲分析

给出细长尖头刚性弹（如尖卵、尖锥形）斜侵彻/穿甲金属靶的一个分析模型。在细长尖头弹对中厚度金属靶的斜穿甲中,韧性孔洞扩张为主要的穿甲机理;着靶初期,发生方向角的改变。研究表明,金属靶的斜穿甲仅由4个量纲一参数控制,即冲击函数I、弹体几何函数N、量纲一靶厚和撞击斜角。分析得到显式的侵彻深度、终点弹道极限、剩余速度和撞击方向改变角表达式。该模型可预期跳飞发生的临界条件。理论预期与实验结果吻合较好。     

On the deep penetration and plate perforation by rigid projectiles

We present results of a large number of 2D numerical simulations in which we investigated various aspects in the deep penetration of rigid short projectiles into semi-infinite targets, as well as their perforation through thin metallic plates. In particular, we analyze the effect of the entrance phase on the penetration characteristics of short ogive and spherical nosed projectiles. The second issue which we investigate here concerns the perforation of metallic plates by sharp nosed projectiles. Our simulation results show that a simple model, which is based on energy conservation, accounts for the residual velocities when the target is penetrated by the ductile hole enlargement process. In addition, we define a new concept, the effective resisting stress which the plate exerts on the projectile during perforation. We show that it has some valuable insights for the process of perforation and we perform a parametric study to understand its dependence on various parameters. This effective stress, which determines the ballistic limit velocity of the projectile, depends on the strength of the plate, as well as on its thickness, as we show here.     

Oblique Perforation of Thick Metallic Plates by Rigid Projectiles

Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several non-dimensional numbers, i.e., the impact function, the geometry function of projectile, the non-dimensional thickness of target and the impact obliquity. Explicit formulae are obtained to predict the ballistic limit, residual velocity and directional change for the oblique perforation of thick metallic plates. The proposed model is able to predict the critical condition for the occurrence of ricochet. The proposed model is validated by comparing the predictions with other existing models and independent experimental data.The English text was polished by Keren Wang     

3D numerical simulations of ductile targets subjected to oblique impact by sharp nosed projectiles

Three-dimensional numerical simulations have been performed to study the behaviour of ductile targets subjected to normal and oblique impact by sharp nosed cylindrical projectiles. Twelve-mm-thick Weldox 460 E steel targets were impacted by 20 mm diameter projectiles with conical nose and 1-mm-thick 1100-H12 aluminum targets were impacted by 19 mm diameter ogive nosed projectiles. In both the cases, the targets were impacted at 0°, 15°, 30°, 45° and 60° obliquity or until the ricochet of the projectile occurred. The ballistic limit of 12 mm steel targets was found to be almost same up to 30° obliquity and thereafter it increased sharply. However, in the case of 1 mm aluminum targets a consistent increase in the ballistic limit was observed with increase in obliquity. The critical angle of projectile ricochet was found to increase with increase in impact velocity. Both the targets failed through ductile hole enlargement. Petal formation occurred in the aluminum targets and four petals were generally formed in each plate, however, the size of the upper two petals decreased and that of the lower two petals increased with increase in target obliquity. In the case of the steel targets the perforation occurred through the formation of a hole enclosed by a bulge. Both the bulge and the hole were circular in normal impact and elliptical in oblique impact. Petal formation in steel targets was observed at 60° obliquity. The ABAQUS/explicit finite element code was used to carry out numerical simulations.     

Effect of air gap and order of plates on ballistic resistance of two layered armor

The high velocity normal impact of a three-dimensional rigid conical impactor penetrating into a two-layered ductile armor with an air gap is studied using a simplified model for an impactor–armor interaction. The goal of the study is to investigate analytically the dependence of the ballistic resistance of the armor on the order of the plates in the armor and on the width of an air gap between the plates. It is found that the ratio between the values of a single parameter depending on the material properties of the plates determines this dependence in both cases. This parameter characterizes the properties of the material of the plate; for the most widely used models of impactor–armor interaction, it is the ratio of the distortion pressure to the density of the plate.     

Q235钢板对半球形头弹抗侵彻特性

利用轻气炮进行了半球形头杆弹正撞击单层板和等厚接触式三层板的实验, 得到了这两种结构靶体的初始-剩余速度曲线以及弹道极限。采用ABAQUS/EXPLICIT数值模拟软件对杆弹撞击金属板的过程进行了数值模拟研究, 通过对比数值模拟和实验结果, 验证了数值模拟材料模型和参数的有效性。研究了靶体结构对抗侵彻特性的影响, 并分析了弹体对靶体的撞击过程。研究结果表明:多层板的弹道极限高于等厚单层板。单层板主要失效模式为剪切, 而多层板的主要失效模式为整体的蝶形变形和局部的盘式隆起。对于多层板, 靶板具体的失效模式与其在靶中位置相关。     

A membrane model for the response of thin plates to ballistic impact

The axisymmetric response of an infinite plate to an impacting projectile is determined analytically on the hypothesis that, for large deformations, a ductile plate behaves to a good approximation like a membrane under uniform tension. The lowest projectile velocity that results in perforation (the ballistic limit), and the residual velocity after perforation, then are determined on the basis of a critical-strain failure criterion. A figure of merit that depends only on the material properties of the target and characterizes the resistance of the material to impact appears naturally in the analysis. Variations in the ballistic limit with target thickness and projectile dimensions can be determined when this figure of merit is known. The theoretical ballistic limit and residual velocity for a steel cylinder impacting a titanium plate are found to agree with available measured values. Further support for the membrane model and an estimate of its range of validity are obtained by comparing the maximum displacement of an impulsively-loaded, circular membrane with experimental data for circular plates.     

Behaviour of uniaxially preloaded aluminium plates subjected to high-velocity impact

The purpose of this paper is to evaluate the behaviour of structural thin plates made of 7075-T6 aluminium alloy under normal impact of spherical steel projectiles, when they are subjected to uniaxial in-plane tensile preload. Also, nonloaded plates were tested under high-velocity impact. The impact and residual velocity were measured in all tests. From the relationships between the impact and residual velocities, the ballistic limit was estimated by a least-squares method. No significant differences were found between the ballistic limits under the two loaded conditions. Above the ballistic limit in the preloaded plates, unstable cracks that can generate the catastrophic failure of the plate were observed. At similar velocities, this phenomenon was not observed in nonloaded plates.