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。     

板间距对铝板多冲击结构高速撞击防护性能影响的试验研究

为了研究板间距变化对铝板多冲击结构高速撞击损伤与防护特性的影响,采用二级轻气炮发射铝球弹丸对具有不同板间距的双层、三层、四层和五层铝板结构进行了高速撞击试验,弹丸直径分别为3.97 mm、5 mm和6.35 mm,撞击速度为1.72~4.88 km/s,撞击角度为0°。结果表明:在铝球弹丸的弹道段撞击速度区间,板间距变化对铝板多冲击结构的高速撞击防护性能无显著影响;在铝球弹丸的破碎段撞击速度区间,对于相同的总防护间距,具有不同板间距的铝板多冲击结构的高速撞击防护性能存在明显差异;基于该试验数据定义的三层、四层和五层铝板结构的板间距因子,可为具有高效抗高速撞击能力的铝板多冲击结构的板间距设计提供依据。     

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。     

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。     

基于动能耗散的双层铝板结构的高速撞击防护性能

通过铝球弹丸高速撞击单层铝板和双层铝板结构的动能耗散特性分析,在弹丸未破碎和已破碎两种撞击条件下,基于单层铝板撞击失效临界动能研究了双层铝板结构的高速撞击防护性能,并针对典型铝板防护结构的高速撞击防护性能评估结果进行了实验验证。结果表明,当铝球弹丸高速正撞击一定厚度的单层铝板时,铝板发生穿孔失效时的临界撞击动能近似为常数。当铝球弹丸高速正撞击双层铝板结构时弹丸击穿前板后的剩余动能,表现为弹丸初始撞击动能的比例耗散。在弹丸破碎段撞击速度区间,使双层铝板结构后板发生穿孔失效的弹丸直径越大,在弹丸击穿前板后的撞击后板有效动能中次生小碎片动能所占的比例越大。     

超高速弹丸撞击靶板的脉冲X光照相实验研究

双层靶结构是一种有效的太空防护结构,对速度为5～7km/s的小颗粒弹丸具有极好的防护作用。为研究双层靶结构的防护作用,用二级轻气炮发射超高速弹丸撞击靶板,用脉冲X光摄影系统拍摄弹丸撞击靶板后形成的碎片粒子云团。对照见证靶被侵彻的形态,可以得到内涵十分深刻的实验数据。自动跟踪式脉冲X光摄影系统是一种新型的脉冲X光摄影系统。应用该系统成功地拍摄了高速弹丸撞击靶板后弹、靶形成碎片粒子云团的形态。文章披露了铝弹撞击铝靶,钢弹撞击铅靶后某一时刻的X光拍摄的图象,并对实验结果作了初步分析。     

单层金属板对刚性弹体抗撞击特性的影响因素研究

利用38Cr Si高硬度弹体对Q235钢和45钢的单层靶进行撞击实验,研究单层金属板对刚性弹体抗撞击特性的影响因素,揭示靶体材料特性、靶体厚度及弹体头部形状对靶体抗撞击特性的影响,分析不同撞击条件下靶体主要失效特性的过渡及条件。实验结果表明,弹体头部形状对其弹道极限的影响与靶体厚度、靶体材性力学特性相关。对于薄板,弹体头部形状对低强度材料更为敏感。但是,对于厚板,弹体头部形状对高强度材料更为敏感。靶体的弹道极限随其厚度增加而增加,靶体厚度对卵形头弹的弹道极限影响最大,依次是半球形头弹和平头弹。此外,高强度靶体的弹道极限高于低强度靶体的弹道极限,其中靶体强度对卵形头弹的弹道极限影响最大。     

铝球弹丸高速撞击表面陶瓷化铝板防护结构实验研究

基于陶瓷化铝板设计了单层防护屏结构和双层防护屏结构,利用二级轻气炮对其进行高速撞击实验。用于模拟空间碎片的2017铝球弹丸直径分别为3.97 mm和6.35 mm,撞击速度为1.64~4.96 km/s。分析了铝板表面陶瓷层对防护结构高速撞击损伤及防护性能的影响。结果表明:防护屏表面的陶瓷层可使单层防护屏结构抵御更大速度范围的粒子撞击;以表面陶瓷化铝板为首层防护屏的铝网填充式防护结构有助于撞击粒子的首次破碎以及次生碎片的撞击动能吸收。     

弹体高速侵彻陶瓷复合厚靶的计算模型研究

针对平头弹高速撞击陶瓷复合厚靶的问题,以集中质量法为基础并考虑靶体的内摩擦效应对Fellows模型加以改进,建立侵彻过程的理论计算模型并利用Matlab编程求得不同撞击速度下弹体侵彻复合靶体的侵彻深度,模型得到了试验结果和数值计算结果的验证。参数分析的结果表明,陶瓷厚度的增加可提高复合靶体的抗侵彻能力,但随着初始撞击速度的提高,弹体的侵彻深度增长曲线趋于平缓。     

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。     

Cavity and crater depth in hypervelocity impact

We discuss the depth of cavities and craters caused by hypervelocity impacts as a function of impact parameters such as impact velocity, projectile and target densities, and projectile diameter, in two extreme cases: the penetration of intact projectiles at low impact pressure and the hemispherical excavation at very high impact pressure. The relations between the depth and the impact parameters are obtained. Then, previous experimental results are compiled; crater depth normalized by projectile diameter and the ratio of projectile and target densities is plotted for glass, plastic, and metal projectiles and metal, rock, ice, foam, sheet-stack, and aerogel targets. The trends of the data are consistent with the relations in the extreme cases.     

Hypervelocity impact on isotropic composites with metal or ceramic inclusions

Experimental results of studying the hypervelocity impact on isotropic heterogeneous composites consisting of an epoxy or aluminum matrix containing fine-grained metal (Al, Pb) or ceramic (SiO₂) inclusions are given. The aim of the study is to develop composite materials offering higher penetration resistance to a high-velocity projectile than the component material. This resistance is characterized by the magnitude of the ratio of the crater depth in a thick target to the diameter of spherical projectile. In the case of two particulate composites studied it is shown that the crater depth from impact of steel projectiles is lower about by one projectile diameter than for homogeneous lead or aluminum over the impact velocity ranged from 3 up to 11 km/s.     

铝球弹丸超高速正撞击薄铝板穿孔尺寸研究

利用2017-T4铝球弹丸高速正撞击不同厚度的2A12铝合金板,模拟空间碎片对航天器防护屏的高速撞击作用,分析铝合金板撞击穿孔尺寸特征。铝球弹丸直径为3.18mm~6.35mm,弹丸直径与铝板厚度之比dp/t为1.00~9.96,撞击速度为1.50km/s~6.98km/s,得到了铝球弹丸高速正撞击铝板的穿孔经验公式。实验结果表明:薄铝板高速撞击穿孔直径扩张率与弹丸直径、铝合金板厚度及撞击速度有关。当弹丸直径与铝合金板厚度之比dp/t一定时,薄铝板撞击穿孔直径扩张率随着撞击速度的增大而增大;当撞击速度一定时,薄铝板撞击穿孔直径扩张率与dp/t呈非线性关系,且随着dp/t的增加,对薄铝板撞击穿孔直径扩张率的影响减弱。     

Projectile density, impact angle and energy effects on hypervelocity impact damage to carbon fibre/peek composites

This paper explores the effects of projectile density, impact angle and energy on the damage produced by hypervelocity impacts on carbon fibre/PEEK composites. Tests were performed using the light gas gun facilities at the University of Kent at Canterbury, UK, and the NASA Johnson Space Center two-stage light gas gun facilities at Rice University in Houston, Texas. Various density spherical projectiles impacted AS4/PEEK composite laminates at velocities ranging from 2.71 to 7.14 km/s. In addition, a series of tests with constant size aluminum projectiles (1.5 mm in diameter) impacting composite targets at velocities of 3, 4, 5 and 6 km/s was undertaken at incident angles of 0, 30 and 45 degrees. Similar tests were also performed with 2 mm aluminum projectiles impacting at a velocity of approximately 6 km/s. The damage to the composite was shown to be independent of projectile density; however, debris cloud damage patterns varied with particle density. It was also found that the entry crater diameters were more dependent upon the impact velocity and the projectile diameter than the impact angle. The extent of the primary damage on the witness plates for the normal incidence impacts was shown to increase with impact velocity, hence energy. A series of tests exploring the shielding effect on the witness plate showed that a stand-off layer of Nextel fabric was very effective at breaking up the impacting debris cloud, with the level of protection increasing with a non-zero stand-off distance.     

基于A-T模型的长杆弹超高速侵彻陶瓷靶体强度分析

Alekseevskii-Tate(A-T)模型广泛应用于长杆弹超高速冲击的终点效应分析中。A-T模型对于金属弹靶强度有明确的表达式,而对于陶瓷靶体强度尤其是弹体初始冲击速度大于1 500 m/s时还没有统一的结论。基于长杆钨弹超高速(1 500~5 000 m/s)侵彻三种陶瓷(Al N,B4C,Si C)/铝复合靶体的缩比逆弹道实验数据;基于A-T模型,给出了上述陶瓷材料在不同侵彻速度范围内的靶体强度表达式。进一步通过与47发长杆钨弹超高速(1 250~2 500 m/s)侵彻陶瓷(Al N,B4C,Si C,AD85)/RHA钢复合靶体DOP实验数据对比,验证了提出的陶瓷靶体强度表达式的适用性。     

Target damage from highly oblique hypervelocity impacts of steel spheres against thin laminated targets

Target hole sizes and geometries were measured for a series of highly oblique hypervelocity impacts of steel spheres against thin laminated targets. The impact velocity was nominally 4.6 km/s for most of the experiments with a few tests conducted at 7.3 km/s. Impact obliquity ranged from 60° to 80° from the normal to the target plane. Projectiles were stainless steel spheres with masses of 222 g, 25 g, and 1 g. Targets were laminated MX-2600 silica phenolic bonded to a 2024-T3 substrate. Target thickness, t, was varied to give thickness to projectile diameter, d, ratios of t/d = 0.6 and 0.3 for each projectile. CTH Eulerian wavecode calculations of selected tests were performed to improve our understanding of the experimental results.     

Crater distribution on the rear wall of AL-Whipple shield by hypervelocity impacts of AL-spheres

All spacecraft in low orbit are subject to hypervelocity impact by meteoroids and space debris, which can in turn lead to significant damage and catastrophic failure. In order to simulate and study the hypervelocity impact of space debris on spacecraft through hypervelocity impact on AL-Whipple shield, a two-stage light gas gun was used to launch 2017-T4 aluminum alloy sphere projectiles. The projectile diameters ranged from 2.51 mm to 5.97 mm and impact velocities ranged from 0.69 km/s to 6.98 km/s. The modes of crater distribution on the rear wall of AL-Whipple shield by hypervelocity impact of AL-spheres in different impact velocity ranges were obtained. The characteristics of the crater distribution on the rear wall were analyzed. The forecast equations for crater distribution on the rear wall of AL-Whipple shield by normal hypervelocity impact were derived. The results show that the crater distribution on the rear wall is a circular area. As projectile diameter, impact velocity and shielding spacing increased, the area of crater distribution increased. The critical fragmentation velocity of impact projectile is an important factor affecting the characteristics of the crater distributions on the rear wall.     

Hypervelocity impact in metals, glass and composites

This paper is a review of hypervelocity impact research carried out during the intense activity period leading up to the Apollo lunar missions. It is intended as a historical note on the research into hypervelocity impact phenomena in metallic, glass, and composite materials and the spacecraft applications of that research. The specific areas covered include cratering and spallation in thick, semi-infinite targets, perforation and hole formation in thin, single-thickness targets, spaced dual sheet armor, impact radiation, and impact ionization. Optimum and nonoptimum dual sheet combinations are treated in some detail because of the current interest in hypervelocity impact protection for the Space Station. On the other hand, the treatment of hypervelocity impacts on composites, phenolic resins and thermosetting epoxy systems reinforced with graphite or other high strength fibers, is limited because work in this area has just begun.     

Multiple impact penetration of semi-infinite concrete

An experimental study was performed to gather multiple impact, projectile penetration data into concrete. A vertical firing range was developed that consisted of a 30-06 rifle barrel mounted vertically above a steel containment chamber. 0.41 m cubes of an Air Force G mix concrete were suspended in wet sand and positioned in the steel chamber. The concrete targets were subjected to repeated constant velocity impacts from 6.4 mm diameter steel projectiles with an ogive nose shape and a length to diameter ratio of 10. A laser sight was adapted to the rifle to ensure alignment, and a break screen system measured the projectile velocity. After each impact, the projectile penetration and crater formation parameters were recorded. The penetration and crater formation data were consistent with single impact penetration data from previous studies conducted at Sandia National Laboratories. In addition, an analytic/empirical study was conducted to develop a model that predicted the penetration depth of multiple impacts into concrete targets. Using the multiple impact penetration and crater formation data, a single impact penetration model, developed by Forrestal at Sandia National Laboratories, was extended to account for the degradation of the target strength with each subsequent impact. The degradation of the target was determined empirically and included in the model as a strength-modifying factor. The model requires geometry parameters of the ogive nose projectile, projectile velocity, the number of impacts, and target compressive strength to calculate the overall penetration depth of the projectile.     

Hypervelocity penetration of plate targets by rod and rod-like projectiles

This paper has summarized the results of experimental tests and analytical studies of the hypervelocity impact of rod and rod-like projectiles which were conducted at the Naval Research Laboratory. The results presented here provide relatively simple analytic expressions from which one can calculate the results of a hypervelocity impact of a rod or rod-like projectile even into complex targets under most impact configurations of interest. The methodology does require a knowledge of certain empirical constants which depend on the projectile and target materials. For those cases where the values of these constants have not been provided, they can easily be determined by performing a relatively few experimental impacts.