A3钢钝头弹撞击45钢板破坏模式的数值分析

不同速度范围内的A3钢钝头弹撞击45钢靶板分别表现为泰勒撞击、向日葵型花瓣帽形失效和靶板冲塞穿甲等3种不同的破坏模式,利用LS-DYNA对这种复杂的破坏机理和相应的影响因素进行了数值模拟研究。采用Johnson-Cook强度模型和累积损伤失效模型描述弹靶材料的力学性能,并考虑了塑性变形的绝热温升效应。数值模拟再现了不同破坏模式的失效过程,得到了与实验一致的结果。研究还指出,弹靶的冲塞穿甲实际是在高速撞击下,弹体发生花瓣帽形变形失效后继续穿甲靶板的后续结果。     

细长薄壁弹体的屈曲和靶体等效分析

利用金属靶开展动能深侵彻弹的穿甲屈曲实验研究。实验观察到长/短型弹体动塑性屈曲破坏分别表现为轴向皱褶型和轴向外翻撕裂型2种基本模式。不同的屈曲破坏模式与弹体几何、撞击初条件以及靶材等密切相关。区别于刚性尖头弹穿甲金属靶的韧性隧道开孔,尖头弹因屈曲破坏易变形为钝头形,导致弹体穿透靶板表现为挤凿穿甲。利用薄壁中空柱壳的弹性欧拉屈曲分析和弹体塑性屈服的极限分析给出弹体动塑性屈曲的临界条件。同时给出屈曲实验中混凝土靶和金属靶的等效条件。     

Effect of projectile nose shape,impact velocity and target thickness on deformation behavior of aluminum plates

The present study deals with the experimental and numerical investigations of aluminum target plates impacted by blunt, ogive and hemispherical nosed steel projectiles. The projectiles were normally impacted on the target plates of 0.5, 0.71, 1, 1.5, 2, 2.5 and 3 mm thicknesses at different velocities with the help of a pneumatic gun. Effect of projectile nose shape, impact velocity and plate thickness on the deformation of the target plates was studied. Hemispherical nosed projectile caused highest global deformation (dishing) of the target plates. Ogive nosed projectiles were found to be the most efficient penetrator for the case of plates of thicknesses 0.5, 0.71, 1.0 and 1.5 mm. For the case of plates of thicknesses 2.0, 2.5 and 3.0 mm however, blunt nosed projectiles required least energy to perforate the target plates. The ballistic limit velocity of hemispherical nosed projectiles was found to be highest as compared to the other two projectiles. Finite element analysis of the problem was carried out using ABAQUS finite element code. Results of the numerical analysis were compared with the experiments and good correlation between the two was found.     

A3钢钝头弹撞击45钢板破坏模式的试验研究

为了研究破片模拟弹的终点弹道效应,进行了不同质量A3钢钝头弹(弹径25 mm)撞击45钢板的试验研究,其中A3钢强度弱于45钢。在约200～800 m/s的撞击速度范围内,随着撞击速度的增加,分别观察到弹体出现泰勒撞击、向日葵型花瓣帽形失效及靶板冲塞穿甲三种破坏模式。伴随弹体和靶体经历的不同结构破坏模式,弹材和靶材也经历着相当复杂的材料失效。     

Incremental deformation and penetration analysis of deformable projectile into semi-infinite target

In this paper, a new analytical method for projectile deformation and penetration into a semi-infinite target has been developed. This method is based on separated, successive and incremental steps. In deformation step, the target assumed rigid and the increment of projectile deformation was evaluated, whilst in penetration step, the projectile assumed rigid and the increment of penetration was evaluated. These sequential steps continued untill the projectile stopped.Furthermore, a series of ballistic tests have been carried out with ogival projectiles with striking velocity of 600–900 m/s. The projectiles and target plates material has been chosen from 4 types of steel. In this way, 210 tests for 48 combinations of projectile, target and velocity have been carried out. Numerical simulation has been also performed using the LS-DYNA code.Comparison between the depth of penetration obtained by this analytical method and those of the experimental and numerical ones shows a good agreement.     

A numerical study on the deformation and fracture modes of steel projectiles during Taylor bar impact tests

A heterogeneous material model based on macro-mechanical observations is proposed for simulation of fracture in steel projectiles during impact. A previous experimental study on the deformation and fracture of steel projectiles during Taylor bar impact tests resulted in a variety of failure modes. The accompanying material investigation showed that the materials used in the impact tests were heterogeneous on scales ranging from microstructure as investigated with SEM to variation in fracture strains from tensile tests. A normal distribution is employed to achieve a heterogeneous numerical model with respect to the fracture properties. The proposed material model is calibrated based on the tensile tests, and then used to independently simulate the Taylor bar impact tests. A preliminary investigation showed that the simulations are sensitive to assumptions regarding the anvil behaviour and friction properties. A flexible anvil and a yield-limited friction law are shown to be necessary to correctly reproduce the experimental behaviour. The proposed model is then shown to be capable of correctly reproducing all fracture modes but one, and also predict critical impact velocities for projectile fracture with reasonable accuracy. Fragmentation at velocities above the critical velocity is not well reproduced due to excessive element erosion. Measures to make the element erosion process more physical are proposed and discussed with their respective drawbacks. The use of a simple fracture criterion in combination with an element erosion technique accentuates the effect of distributing the fracture parameter.     

Ti-6Al-4V弹体破坏模式对冲击反应的影响研究

Ti-6Al-4V材料是武器结构轻量化时的重要替代材料，其冲击反应将可能增加战斗部毁伤威力，但目前缺乏对其冲击反应条件及反应机理的研究。本文将采用试验与理论分析方法，研究结构破坏模式对Ti-6Al-4V材料冲击反应的影响，获得其冲击反应条件及反应机理。设计并开展了钛合金弹（头部与壳体均为钛合金）与复合弹（头部碳/碳复合材料、壳体空心钛合金圆柱）正侵彻混凝土试验，撞击速度在222~1008 m/s之间。钛合金弹激发了剧烈的氧化冲击反应，但复合弹未产生冲击反应。破坏模式宏细观分析显示，钛合金弹侵彻后宏观结构基本完整，仅表面发生摩擦磨损，以细观组织剪切变形为主要失效模式，形成尺寸在微米量级至百微米量级的颗粒碎片，碎片个数可高达3×106。复合弹的钛合金空心圆柱被撕裂成块，撕裂面沿剪切带方向发展，碎块尺寸在毫米或以上量级，个数至多百余个。碎片供氧和供热的效率均与碎片尺寸成反比，而特定供氧与供热条件下，碎片尺寸足够小是Ti-6Al-4V材料发生冲击反应的必要条件，这是钛合金弹发生冲击反应而钛合金空心圆柱无法激发冲击反应的本质原因。在具备冲击反应必要条件的前提下，碎片个数越多，冲击反应烈度越高。     

大长细比结构弹体侵彻2024-O铝靶的弹塑性动力响应

为研究大长细比结构弹体在撞击典型硬目标早期的结构动力学响应,利用57轻气炮进行了直径1.4 cm、量纲一壁厚0.1和0.15、长细比8和12、头部系数3和4.5的卵形空心弹体对2024-O铝靶的侵彻实验研究,利用高速摄影系统记录了弹体撞靶过程,观察到大长细比弹体垂直撞击硬目标过程中的局部墩粗、塑性屈曲2种结构破坏模式,以及斜侵彻过程中的整体塑性弯曲、弯曲与墩粗耦合、弯曲与屈曲耦合3种结构破坏模式和实时动力学响应过程。基于对指数硬化材料的空腔膨胀理论建立了弹体垂直侵彻模型,给出了在轴向及横向载荷交互作用下计算刚塑性自由梁危险截面屈服函数的控制方程,计算值与实验结果吻合较好。     

基于物质点法的船体板架结构高速侵彻毁伤模式研究

本文通过数值模拟的方法研究了截卵型弹体冲击下921A钢板的毁伤模式。 跟以往试验进行对比，发现数值结果与实验结果吻合良好。 在3种不同工况下，剩余速度与实验结果吻合良好，误差小于5%。随着弹着点位置的变化，加筋板的失效模式发生变化。击中靶板中心时，加强筋发生撕裂，目标板在左右两侧产生对称的花瓣型破坏模式。 随着弹着点位置的偏移，加强筋的撕裂程度逐渐减小，最后仅仅发生塑性应变。并且目标板上的破坏不再对称，左侧板的动态响应从花瓣破坏变为小面积断裂，最后仅保留塑性变形。右侧板始终产生花瓣型失效模式，但花瓣的数量和形式始终在变化。结果表明，物质点法可以很好地应用，并为今后舰船穿透研究提供参考。     

80%钨纤维增强锆(Zr)基块体金属玻璃复合材料长杆弹侵彻钢靶实验研究

本文在765~1766m/s速度范围内,对钨纤维体积分数为80%的增强锆(Zr)基块体金属玻璃复合材料长杆弹进行侵彻Q235钢靶的穿甲试验,对残余弹体进行宏、细观观测,研究弹体材料的失效破坏模式。穿甲试验表明,在大于1000m/s速度侵彻时,钨纤维非晶弹拥有头形自锐能力,表现出优秀的侵彻能力。弹材变形和破坏主要发生于弹体头部边缘层,呈局域化和尖锐化特点,而且边缘层厚度在整个高速穿甲过程中保持动态平衡。由于非晶基体作用,弹体材料易发生剪切断裂等破坏,通过流动形成质量侵蚀并导致弹体头部边缘层形成自锐。     

Kevlar层合板动静态侵彻贯穿特性的实验研究

本文以Kevlar/环氧树脂层合材料为对象,通过动静态侵彻实验,研究层合板的抗贯穿特性。利用MTS810材料试验机进行准静态侵彻实验,根据测得的加载载荷-位移曲线及靶板的破坏模式,分析了靶板的准静态侵彻行为。实验指出,准静态侵彻时层合板的整体弯曲变形是其主要吸能模式,织物铺层板的吸能量要高于无编织铺层板,表现出更好的抗侵彻性。采用7.62mm口径滑膛枪开展了初速为200～700m/s的弹道冲击实验,讨论了不同弹形弹丸侵彻靶板的效果以及不同铺设方式靶板的抗弹性能和破坏模式。通过与准静态侵彻实验结果的对比,发现靶板的抗侵彻性能和破坏模式与侵彻速度有明显关系。动态侵彻时层合板的破坏局域化,破坏模式多样化。弹形对侵彻效果的影响主要体现于接近弹道极限的低速段。     

装甲钢/UHPC复合靶体抗侵彻性能试验与数值模拟研究

装甲钢/超高性能混凝土（UHPC）复合防护结构在重点工程中抵抗弹体的高速侵彻作用具有广泛的应用前景。为评估该复合结构的抗侵彻性能,对两种复合靶体开展侵彻试验与数值模拟研究。首先,开展了12发30 mm口径30CrMnSiNi2A弹体372~646 m/s速度侵彻复合靶试验。随后通过一系列静动态力学性能试验标定装甲钢材料的本构模型参数,并建立三维有限元模型对上述试验开展数值模拟分析。通过对比试验和数值模拟得到的弹体侵彻深度、残余弹体长度和装甲钢板的失效模式,验证了装甲钢本构模型参数的可靠性。进一步基于弹道效益系数对复合靶抗侵彻性能进行了定量评估。最后,确定了不同装甲钢板厚度复合靶体的临界贯穿速度,并对弹体侵彻复合靶的弹、靶失效模式进行了讨论。     

Perforation of steel and polycarbonate plates by tumbling projectiles

An experimental investigation to assess the effect of tumbling by hard-steel, blunt-faced cylindrical projectiles on the impact response of thin 4130 steel and polycarbonate target plates was performed. Deformation and failure phenomena were observed and discussed; comparisons of the results with analytical models and numerical stimulation, described in a previous paper, were also performed for the steel targets. The final velocity of the projectile and the crater length in the target were correlated with the striker impact angle (or yaw angle with a zero oblique angle); reasonable agreement was attained among the experimental, analytical and numerical results. It was found that an increase of the impact angle can increase the velocity drop and the crater length markedly. The increase tends to be stabilized after the impact angle exceeds 50° and the consequences in such a case are almost the same as in side-on impact.     

不同撞击速度下穿燃弹侵彻陶瓷/铝合金复合靶板时弹芯破碎失效特性研究

为了研究12.7 mm穿燃弹以不同速度撞击陶瓷/铝合金复合靶板时弹芯的破碎及失效特性,开展了12.7 mm穿燃弹以434.5～844.6 m/s速度撞击SiC陶瓷/6061T6铝合金复合靶板的弹道试验,分析了弹靶的失效模式。弹芯在侵彻靶板后会产生不同尺寸的碎片,使用回收箱收集弹芯碎片并用不同孔径筛网对其进行筛分、称重,得到了不同撞击速度下弹芯碎片的质量分布,并对不同部位的弹芯碎片断口形貌进行了宏观和微观观测分析。研究结果表明:背板失效模式为碟形变形-剪切穿孔-花瓣形失效,试验后的弹芯碎片累积质量分布符合Rosin-Rammler幂率分布规律,且随着着靶速度的增大,小质量碎片质量增加;弹芯在冲击过程中等效直径较大碎片（大于8 mm）失效模式为拉伸脆性断裂,而等效直径小于2 mm的碎片上存在局部塑性剪切断裂。     

在椭圆横截面弹体正侵彻下有限厚铝靶的破坏模式及响应特性

基于30 mm口径弹道炮平台,开展了3种不同椭圆横截面弹体在200~600 m/s撞击速度范围内正侵彻2A12铝靶的实验,获得了2A12铝靶的破坏形貌及弹体的剩余速度。在此基础上,建立了相应的数值模型,结合实验结果验证了所建模型的有效性,并系统分析了弹体横截面长短轴长度比对靶体的破坏情况及响应特性的影响。研究结果表明:弹体最大横截面面积是影响弹体剩余速度的主要因素,而弹体横截面长短轴长度比对弹体剩余速度的影响较弱;在圆形横截面弹体侵彻下靶体背部形成的花瓣大小和形状一致,空间分布均匀,而在椭圆横截面弹体侵彻下,随着弹体横截面长短轴长度比的增大,靶体背部形成的花瓣数量增加、尺寸变小,且在短轴方向的花瓣数量和靶体表面隆起高度均大于长轴方向的;靶体在圆形横截面弹体侵彻下的径向位移、径向应力和切向应力与其在椭圆横截面弹体侵彻下的显著不同,前者沿周向方向各点的变化规律基本一致,靶体处于简单的压缩状态,切向应力为零,而后者各点的应力状态与弹体横截面长短轴长度比和周向角密切相关,靶体受到压缩和剪切应力的耦合作用。     

弹体超高速侵彻石灰岩靶体地冲击的数值模拟研究

为探究超高速动能武器的对地破坏效应及其影响因素,采用数值模拟方法对弹体超高速侵彻的地冲击规律进行了研究。首先,基于石灰岩静动态力学性能实验数据对材料模型参数进行了标定,并对已有弹体大范围着速侵彻石灰岩靶体进行了模拟,验证了所采用材料模型和数值模拟方法的合理性。随后,开展了钨合金长杆弹超高速侵彻石灰岩靶体的数值模拟,细致分析了地冲击传播的现象和机理:弹体超高速侵彻靶体时,弹靶交界面处会产生瞬时高压,并以应力波的形式在靶体中传播,对靶体内部造成破坏,且当弹体初速度高于3.0 km/s时,地冲击显著增强。最后,进一步研究了不同弹靶参数对地冲击的影响,发现从相对深度来看,弹体参数（弹体长径比、密度）对地冲击规律影响不大;而靶体特征特别是孔隙率对地冲击传播具有较大影响。     

弹体高速侵彻钢筋混凝土靶试验研究

为研究结构弹体对钢筋混凝土靶的高速侵彻破坏效应,利用口径35 mm弹道炮开展了1 030～1 520 m/s速度范围内的高速侵彻试验,获得了弹体的撞击速度、破坏形态、剩余长度、剩余质量和靶体中的侵彻深度及成坑尺寸等试验数据,分析了侵彻深度和侵彻机理随速度的变化关系。结果表明:在1 030～1 390 m/s的速度范围内,弹体头部磨蚀,磨蚀程度随侵彻速度增加而加剧,侵彻深度随撞击速度近似线性增大;撞击速度在1 390～1 480 m/s范围内,弹体头部严重磨蚀,侵彻深度随撞击速度增加而减小;撞击速度大于1 480 m/s后,弹体严重破碎,侵彻深度急剧下降。针对结构弹体高速侵彻过程中的破坏特点,将侵彻速度划分为刚体侵彻区、准刚体侵彻区、侵蚀体侵彻区和破碎体侵彻区,可为钻地弹结构设计提供参考。     

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.     

A study of the perforation of stiffened plates by rigid projectiles

In the present paper, a four-stage perforation model that accurately predicts the residual velocity is developed by adopting an energy method. The four stages are plug formation, dishing formation, petal formation and projectile exit. In addition, some important experimental results are presented and analyzed to validate the present perforation model. In the experiments, high speed camera system is used to record the perforation process. Observations on target damage and measurements of initial velocities and residual velocities with the aid of the system are presented. Numerical simulations are carried out for projectiles against single and layered plates adopted in the experiments. The perforation process is studied and the deformation and failure modes are obtained. The predictions of numerical simulations and analytical model are found in reasonably good agreement with those of experiments, and can be used to predict the ballistic limit and residual velocity of stiffened plates perforated by rigid projectiles. The project supported by the National Natural Science Foundation of China (90305018) The English text was polished by Yunming Chen     

W25Fe25Ni25Mo25高熵合金高速侵彻细观结构演化特性

为了探究W₂₅Fe₂₅Ni₂₅Mo₂₅高熵合金弹体在侵彻过程中宏观变形行为与材料微细观结构之间的联系, 基于对两相流动模型的简化, 建立了考虑软、硬相密度、流速以及浓度差异的等截面直管两相流动演化模型. 类比宏观状态下侵彻弹体头部材料的流入流出特性, 选定分析区域, 建立两相细观结构下材料在分析区域的流入流出关系, 再结合细观结构演化方程, 给出了分析区域中浓度演化结果, 提出了表征材料浓度演化速率的流动稳定系数t/l_length. 为了对比不同细观结构弹体的侵彻行为, 选取典型两相材料钨铜合金(W₇₀Cu₃₀), 基于小口径弹道枪发射平台开展两种弹体侵彻半无限钢靶试验, 对比两种合金弹体细观结构演化行为. 结果表明, 硬相浓度分布总体上体现“中心浓, 边缘稀”的特点; 硬相的浓度越高, 密度越大, 驱动速度越快, 则流动稳定系数t/l_length值越小, 侵彻过程中弹体的流动稳定性越好, 弹体头部材料越容易形成连续的塑性流动带. 等截面直管两相流动演化模型可用于描述侵彻过程中弹体头部材料的流动稳定性, 揭示了侵彻过程中弹体头部变形与细观两相结构之间的关联机制.