刚性卵形头弹撞击角度对编织复合材料层合板侵彻特性的影响

利用一级气炮发射卵形头弹撞击2 mm厚度的编织复合材料层合板,撞击角度分别为0°、30°和45°,通过高速相机记录弹靶撞击过程,并获得弹体速度数据。基于拟合公式处理试验数据,计算获取弹道极限,分析撞击角度对弹道极限、靶板能量吸收率及其失效模式的影响规律及机制。结果表明：弹体撞击角度为45°时,靶板弹道极限最高,其次为0°,撞击角度为30°时最小。随着冲击角度增加,层合板损伤形状从菱形逐渐转变为椭球形,损伤面积随冲击速度增加而增大,且45°冲击时层合板损伤面积最大,0°和30°冲击时损伤面积近似相等。弹体初始撞击角度对靶体失效模式存在影响,弹体撞击角度为0°时,纤维断口主要是剪切应力导致的横截面。撞击角度为30°时,纤维断口主要是剪切应力和拉伸应力导致的斜截面。45°斜撞击时,纤维断口主要是拉伸应力导致的横截面。     

弹体头部形状对碳纤维层合板抗冲击性能影响实验研究

为研究弹体头部形状对碳纤维层合板抗冲击性能的影响,利用一级气炮发射卵形头弹、半球形头弹和平头弹,对2 mm厚碳纤维层合板进行了冲击实验。利用公式拟合处理实验数据,揭示弹体头部形状对靶板弹道极限与能量吸收的影响,并且分析靶板冲击损伤形貌及机理特征。研究结果表明:平头弹弹道极限最高,半球形头弹次之,卵形头弹最低。弹体在低速度冲击时,弹体头部形状对靶板能量吸收率的影响更为显著。平头弹冲击时,靶板迎弹面受到均匀分布的环向剪切力,纤维同时被剪切,基体发生大面积剪切破坏。半球形头弹冲击时,靶板迎弹面受到非均匀分布的剪切力和挤压作用,纤维发生剪切断裂和拉伸断裂,基体发生剪切破坏和挤压破碎。卵形头弹冲击时,纤维发生单一的拉伸断裂,而基体则发生挤压破碎。弹体头部形状对靶板损伤的影响主要集中在迎弹面和中部纤维层。     

单层A3钢薄靶在不同头型弹体斜撞击下的失效模式和防护性能研究

利用轻气炮设备对平头、卵形弹进行了以5种角度撞击2 mm单层A3钢薄靶的斜穿甲试验,得到了不同头型弹体在各个角度撞击单层靶的初始-剩余速度曲线及靶板的弹道极限,获得并对比分析了弹体头部形状、撞击角度对靶板的防护性能及失效模式的影响。结果发现,平头弹在各个撞击角度下较卵形弹更容易击穿靶板,撞击角度较大时卵形弹较平头弹更容易发生跳飞现象;靶板的防护性能与弹体造成的靶板损伤和失效模式紧密相关,随着斜撞击角度变大,平头弹造成的靶板局部穿孔毁伤模式逐步由剪切冲塞失效转向以拉伸撕裂失效为主,同时整体结构弯曲和膜变形减小,而薄板在卵形弹斜撞击下的失效模式则以局部斜形非对称花瓣开裂为主。     

间隙对A3钢薄板抗卵形头弹侵彻性能影响的实验研究

为了分析板间间隙大小对双层板失效模式以及抗侵彻性能的影响,本文利用轻气炮进行了卵形杆弹正撞击单层板和等厚双层板的实验研究,得到了各种结构靶体的初始-剩余速度曲线和弹道极限速度。实验表明,对于卵形弹,单层板的弹道极限高于双层板的弹道极限,包括接触式和间隙式。当总厚度一定时,多层板的弹道极限随分层数目的增加而减小。此外,间隙大小对间隙式双层板的抗侵彻性能影响小,并且随着弹体初始速度的增加而减小。     

TC4钛合金板厚度对其撞击失效特性影响研究

为了揭示TC4钛合金板抗撞击性能与失效模式随厚度的变化规律及机理,采用ABAQUS/Explicit有限元软件建立平头弹撞击不同厚度靶板的模型,对弹体撞击不同厚度靶板进行计算。通过对比数值仿真与撞击实验结果,验证仿真模型的有效性。研究结果表明,靶板的主要失效模式、耗能机制、弹道极限随其厚度增加会发生改变,靶板厚度存在对应的转折值。对于TC4钛合金薄板,当靶板厚度比较小时,靶板拉伸撕裂破坏占主导作用。但是,当靶板厚度比较大时,靶板主要失效模式是局部剪切破坏。当靶板厚度小于4 mm、大于8 mm时,弹道极限速度随靶板厚度的增加而增加;当厚度为4~8 mm时,弹道极速度变化不明显。     

分层对TC4钛合金板抗平头弹撞击失效特性的影响

使用Abaqus/Explicit有限元分析软件,开展平头弹撞击不同厚度双层TC4钛合金板数值模拟,研究双层TC4钛合金板撞击失效特性与失效模式随厚度变化规律及机理。通过对比撞击试验与仿真结果,验证数值模型和参数的有效性。在此基础上与等厚度单层TC4钛合金板的抗侵彻性能进行对比,结果表明,对于12.68 mm直径的平头弹,在靶板厚度2~16 mm内,双层结构的弹道极限与总厚度近似呈线性关系。由于单层靶板在4~10 mm内随着厚度增加,弹道极限无明显变化,所以等厚接触式双层结构在该厚度范围相比单层靶有明显的优势。在总厚度为8 mm时,双层靶优势最为明显,弹道极限相比单层靶提高了43%左右。     

金属薄靶板冲塞破坏最小穿透能量分析

基于大量弹道极限试验分析和高应变率下材料的简化热塑性本构关系,提出一种计算塑性金属靶板在刚性平头弹亚弹速冲击下冲塞剪切耗能的简化模型,建立了刚性平头弹穿透靶板所需最小能量(最小穿透能量)的无量纲表达式,得到一个计算低碳钢靶板最小穿透能量的半理论半经验公式。介绍并分析讨论了现有金属靶板最小穿透能量经验公式,得到一些有意义的结论。经分析比较,表明本文公式适用性较广、精度较好。     

2A12铝合金薄板对卵形头弹抗冲击性能研究

利用轻气炮撞击实验研究卵形弹丸冲击总厚度相等的2A12铝合金单层板和双层板,分析靶板分层和板间间隙对靶板失效模式以及抗冲击性能的影响,通过高速相机图片获取弹体速度数据。实验结果表明,单层板的弹道极限高于双层板的弹道极限,包括间隙式和接触式,并且接触式双层板的弹道极限高于间隙式双层板。随着弹体初始速度增加,靶体结构对其抗侵彻性能的影响随之减小。此外,利用Abaqus软件建立了数值模拟模型对实验工况进行了计算,将数值模拟和实验结果进行了对比,两者之间存在较好的一致性,这也表明数值模拟能够有效地测靶体的弹道极限。     

7A04-T6高强铝合金板对平头杆弹抗侵彻行为的试验与数值模拟研究

为了解高强铝合金对动能杆的抗侵彻性能,在一级轻气炮上开展了直径5.98 mm的平头刚性弹侵彻6mm厚7A04-T6铝合金靶板的打靶试验,撞击速度范围为73.9~446.5 m/s。获得了弹体贯穿靶板后的剩余速度以及靶板的断裂行为,通过拟合初始-剩余速度数据得到了弹道极限。同时,在ABAQUS/Explicit中建立了三维有限元模型对打靶试验进行了数值计算,7A04-T6的力学行为通过Johnson-Cook本构模型和修正的Johnson-Cook断裂准则描述。试验结果表明,7A04-T6高强铝合金靶板在平头弹撞击下发生剪切冲塞,塞块表面有明显裂纹产生,弹道极限为156.0 m/s,剪切冲塞可在撞击速度不低于约0.90倍弹道极限时形成。数值仿真发现,有限元计算可成功再现靶板的剪切冲塞及冲塞表面的断裂;预报的弹道极限为168.8 m/s,比试验结果高约9%;撞击速度不低于0.92倍弹道极限时靶板发生剪切冲塞破坏,与试验结果十分接近。     

尖头弹侵彻延性金属靶板弹道极限的解析模型

现有的尖头弹侵彻金属靶板的弹道极限计算模型往往需要大量的试验数据和靶板材料的动态性能参数,且没有考虑侵彻速度对侵彻效果的影响,这给工程应用带来了很大的不便和误差。基于这一问题,考虑速度效应和靶板材料参数对侵彻的影响,结合流体动力学原理与动态空穴膨胀理论,分别提出了双模式和单模式侵彻模型。双模式侵彻模型的侵彻过程可分为两个阶段：流体动力变形阶段和塑性变形阶段,当侵彻速度小于靶材产生流体动力变形的临界速度时,侵彻进入塑性变形阶段,根据功能原理,建立了计算弹道极限的解析模型;单模式侵彻模型仅考虑塑性变形阶段。解析模型计算的弹道极限与弹道试验结果吻合的较好,且模型中不涉及弹道试验数据和靶板材料的动态性能参数,易于迅速求解,便于工程应用,可用于对延性金属靶板抗尖头弹侵彻能力的评估。     

Direct force measurement in normal and oblique impact of plates by projectiles

An experimental investigation of the forces produced by the penetration and perforation of thin aluminum and steel plates by cylindro-conical and hemispherically-tipped projectiles at 0, 15, 30 and 45° angles of incidence has been performed. Additionally, force histories were recorded for normal impact on Lexan, nylon and ceramic targets by conically-tipped strikers. Similar tests on Kevlar were not successful owing to the generation of voltages by rubbing of fibers that completely overwhelmed the transducer signal. A piezoelectric crystal bonded to the tail of the 12.7 mm diameter, 30 g projectiles followed by an inertial mass and a trailing wire provided the instrumentation. The strikers were propelled by means of a pneumatic gun at velocities ranging from 45 to 170 ms⁻¹. Displacement data obtained from high-speed photography for selected runs allowed curve fits to an analytical function which were compared to the directly recorded force histories.The effects of changes in initial velocity, angle of obliquity and striker tip on the peak force have been analyzed. A simple model has been developed for the perforation of plates by hemispherically-tipped projectiles at oblique incidence, and comparisons have been made with the measured force histories. A model was also devised to predict the peak forces obtained for oblique impact by cylindro-conical projectiles. The peak forces obtained experimentally were found to be relatively independent of the initial projectile velocity for shots where perforation occured. For the tests at speeds below the ballistic limit, the maximum forces were approximately proportional to the initial velocity.     

The ballistic performance of metal plates subjected to impact by projectiles of different strength

In this paper, the ballistic performance of monolithic, double- and three-layered steel plates impacted by projectiles of different strength is experimentally investigated by a gas gun. The ballistic limit velocity for each configuration target is obtained and compared based on the investigation of the effect of the number of layers and the strength of projectiles on the ballistic resistance. The results showed that monolithic plates had higher ballistic limit velocities than multi-layered plates for projectiles of low strength regardless their nose shape, and also the ballistic limit velocities of plates decreased with the increase of the number of layers. Moreover, monolithic plates showed greater ballistic limit velocities than multi-layered plates for ogival-nosed projectiles of high strength, and also the ballistic limit velocities of plates decreased with the increase of the number of layers. However, monolithic plates had lower ballistic limit velocities than multi-layered plates for blunt-nosed projectiles of high strength, and also the ballistic limit velocities of plates increased with the increase of the number of layers. The differences in the ballistic limit velocities between various impact conditions can be related to the transitions of perforation mechanisms and failure models of plates and projectiles.     

A numerical comparison of the ballistic performance of unitary rod and segmented-rods against stationary and moving oblique plates

The purpose of this paper is to investigate the ballistic performance of segmented-rods against stationary or moving oblique plates. To do this, a series of three-dimensional numerical simulations for the impact characteristics of segmented-rods (5 of L/D=1) into stationary or moving oblique thin-plate targets is conduced. To provide a base line data, an L/D=5 unitary rod projectile which has the same mass and kinetic energy is also considered. The ballistic characteristics of the projectiles are evaluated by examining the crater profile in a thick witness target that is placed behind the oblique plate. The impact velocities considered are 1400, 1800 and 2200 m/s. The results for the test range show that the unitary rod projectile shows better performance in the moving oblique target than the stationary one and the segmented-rods always show slightly better performance in the stationary target. From the impact velocity of 2200 m/s, the outstanding penetration performance of the segmented-rods can be observed. This trend is due to the interaction between the reactive plate and projectile. The extent of the interaction relies on the relative velocities of the plate and projectiles, the plate angle and extended total length of the segmented-rods     

Q235钢单层板对平头刚性弹抗穿甲特性研究

采用撞击实验和理论模型对单层金属板的抗侵彻性能进行了研究,分析了靶体厚度对抗侵彻性能的影响。通过对比撞击实验和理论模型计算结果,验证了理论模型和参数的有效性。结果表明,采用合适的理论模型能够有效地预测靶板在弹体撞击下的弹道极限。此外,分析了靶体在弹体撞击下的塑性变形总耗能,包括靶板局部变形和整体变形的耗能,同时考虑了靶体材料的应变率效应。在平头弹撞击厚靶的工况中,引入了一个修正函数对靶体厚度进行修正。     

Normal impact of ogive nosed projectiles on thin plates

Single plates of aluminium of various thicknesses were subjected to normal impact by ogive nosed projectiles at velocities normally greater than their ballistic limit. The observed values of the residual velocity and ballistic limit are presented and influence thereon of various parameters is discussed. Based on the mechanism of deformation observed and the data of residual and incident velocities, analytical and empirical relations have respectively been developed for the determination of both residual velocity and ballistic limit. These relations are seen to match the experiments well.     

Experimental investigation on the ballistic resistance of monolithic and multi-layered plates against ogival-nosed rigid projectiles impact

In this paper, the ballistic performance of single, two-, three- and four-layered steel plates impacted by ogival-nosed projectiles were experimentally investigated. Thin multi-layered plates arranged in various combinations of the same total thicknesses were normally impacted with the help of a gas gun. Ballistic limit velocity for each configuration target was obtained and compared based on the investigation of the effect of the air gap between layers, the number, order and thickness of layers on the ballistic resistance of targets. The results show that the thin monolithic targets have greater ballistic limit velocities than multi-layered targets if the total thickness less than a special value, and also the ballistic limit velocities of multi-layered targets decrease with the increase of the number of layers. Otherwise, the moderate thickness monolithic targets give lower ballistic limit velocities than multi-layered targets. Furthermore, the ballistic limit velocities of in-contact multi-layered targets are greater than those of spaced multi-layered targets. The order of layers affects the ballistic limit velocities of multi-layered targets, the ballistic resistance of the multi-layered targets is better when the first layer is thinner than the second layer.