力学进展  2019 , 49 (1): 201905-201905 https://doi.org/10.6052/1000-0992-17-015

装甲陶瓷的界面击溃效应

谈梦婷1, 张先锋1, 包阔1, 伍杨2, 吴雪1

1 南京理工大学机械工程学院, 南京 210094
2 瞬态冲击技术重点实验室, 北京 102202

Interface defeat of ceramic armor

TAN Mengting1, ZHANG Xianfeng1, BAO Kuo1, WU Yang2, WU Xue1

1 Ministerial Key Laboratory of ZNDY, Nanjing University of Science and Technology, Nanjing 210094, China
2 Science and Technology on Transient Impact Laboratory,Beijing 102202, China

中图分类号:  O385

文献标识码:  A

通讯作者:  † E-mail: lynx@njust.edu.cn

收稿日期: 2017-07-4

接受日期:  2018-02-1

网络出版日期:  2019-01-15

版权声明:  2019 中国力学学会 This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

基金资助:  国家自然科学基金面上项目(11772159)、瞬态冲击技术重点实验室基金项目(6142060101162606001)、南京理工大学自主科研专项计划项目(30917011104)、高性能陶瓷和超微结构国家重点实验室开放课题基金(SKL201602SIC)、江苏省研究生科研创新计划项目(KYCX17_0385)资助项目

作者简介:

张先锋, 博士, 南京理工大学机械工程学院教授, 博士生导师,中国兵工学会军用防护技术专业委员会委员;主要研究方向包括材料动力学行为及损伤, 材料动态本构模型,高效毁伤与防护技术, 爆炸与冲击动力学等; 在International Journal of Impact Engineering, Journal of Applied Physics,Materials and Design等国内外重要期刊上发表论文80余篇,其中SCI(E)收录19篇, EI收录20篇, 申请专利15项;获国防技术发明奖二等奖1项、教育部技术发明奖二等奖1项.

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摘要

界面击溃效应(interface defeat)是射弹撞击陶瓷材料过程中,陶瓷表面产生的特有现象.国内外学者在近30年来对陶瓷界面击溃效应开展的大量研究工作表明界面击溃效应中射弹界面驻留(dwell)时间的增加以及界面击溃/侵彻转变速度的升高能够大量消耗弹体动能、有效提高装甲陶瓷的抗弹性能.本文主要从实验、理论和数值模拟三方面介绍国内外学者开展的工作,包括陶瓷界面击溃效应的宏观与微观力学机制及其研究方法等.针对现今对界面击溃效应研究的不足, 提出了关于未来研究方向的建议.

关键词: 装甲陶瓷 ; 界面击溃 ; 冲击动力学 ; 裂纹扩展

Abstract

Interface Defeat, which can effectively defeat the long-rod projectile (LRP), is a specific phenomenon of ceramic armor. Studies on this area have been conducted for the last three decades both at home and abroad proving that delaying dwell time or increasing interface defeat/penetration transition velocity can defeat projectile and enhance the ballistic performance of ceramic armor. Related researches on the experimental techniques, theoretical models and numerical simulations of interface defeat are introduced, including the study of interface defeat at the micro and macro scale, a method for the design of the ceramic composite armor, etc. According to the insufficient work of interface defeat, some suggestions are proposed in this paper.

Keywords: ceramic ; interface defeat ; impact dynamics ; crack expansion

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谈梦婷, 张先锋, 包阔, 伍杨, 吴雪. 装甲陶瓷的界面击溃效应[J]. 力学进展, 2019, 49(1): 201905-201905 https://doi.org/10.6052/1000-0992-17-015

TAN Mengting, ZHANG Xianfeng, BAO Kuo, WU Yang, WU Xue. Interface defeat of ceramic armor[J]. Advances in Mechanics, 2019, 49(1): 201905-201905 https://doi.org/10.6052/1000-0992-17-015

1 引言

陶瓷具有低密度、高硬度和高压缩强度的特点,可以有效减轻装甲重量并提高装甲的抗弹性能. 随着陶瓷材料力学性能的提高,冲击载荷作用下装甲陶瓷特有的界面驻留/界面击溃现象越来越常见.在射弹界面驻留/击溃过程中, 弹体材料在靶体表面径向流动伴随质量侵蚀、速度下降,而靶体表面未有明显的侵彻现象(Hauver et al. 1992).长杆弹撞击装甲陶瓷的界面驻留/击溃效应与侵彻现象如图1所示(Lundberg 2004).

图1   长杆弹撞击装甲陶瓷的界面驻留/击溃与侵彻现象(Lundberg 2004). (a)界面驻留/击溃效应, (b) 侵彻

   

界面击溃/侵彻转变速度(transition velocity,TV)是描述界面击溃效应及靶体抗侵彻性能的重要参量. 射弹速度较低时,陶瓷表面的驻留效应将持续整个撞击过程, 这种现象称为界面击溃效应.射弹速度较高时, 界面驻留效应只在陶瓷表面持续一段时间, 紧接着弹体侵彻陶瓷,此时对应的射弹撞击速度称为转变速度. 界面驻留时间越长,弹体材料在靶体表面消耗的能量越多, 说明靶体的抗侵彻能力越强.界面击溃向侵彻转变过程示意图如图2所示(Lundberg 2004).国内外学者期望通过延长射弹界面驻留时间和提高界面击溃/侵彻转变速度的方法使射弹能量急剧下降,增强装甲陶瓷的抗弹性能.

图2   界面击溃向侵彻转变过程示意图 (Lundberg 2004)

   

半个世纪以来,陶瓷界面击溃效应的研究工作从最初的获得界面击溃效应(Wilkins 1963;Hauver et al. 1993, 1994, 2005; Rosenberg & Tsaliah 1990;Anderson & Walker 1991; Anderson & Morris 1992;Anderson & Royal-Timmons 1997; Anderson et al. 1993a, 1995, 1999, 2005; Den Reijer 1991; Bless et al. 1992; Lundberg et al. 1996; Westerling et al. 2001)转为研究界面击溃过程中弹、靶动态力学响应(Lundberg 2004, 2007;Lundberg P & Lundberg B 2005; Lundberg et al. 2000, 2001, 2006, 2013, 2016; LaSalvia & McCauley 2010; LaSalvia 2002a, 2002b, 2005a, 2005b; LaSalvia et al. 2001, 2005, 2007, 2009, 2010a, 2010b; LaSalvia & Normandia 2002; Deshpande & Evans 2008; Deshpande et al. 2011; Anderson & Orphal 2003;Pickering et al. 2016), 以明确界面击溃效应作用机理,为界面击溃效应在工程上的应用奠定基础. 在实验方法和技术方面,主要围绕陶瓷材料、弹体形状、尺寸效应等影响因素开展撞击实验,获得不同弹靶条件下的界面击溃效应(Lundberg 2004, 2007; Lundberg P & Lundberg B 2005; Lundberg et al. 2000, 2001, 2006, 2013, 2016). 一方面国内外学者加强了实验观测技术,宏观观测界面击溃过程并对回收后的靶体材料破坏情况进行细观观测,以了解界面击溃效应对弹靶破坏的作用(Anderson et al. 2005, 2008, 2009, 2011a, 2011b; Anderson 2009, 2010; Anderson & Gooch 2011; Lundberg et al. 2000, 2001; Thoma et al. 2007; Strassburgeret al. 2016; Behner et al. 2008, 2016). 另一方面,通过不同影响因素下的界面击溃效应实验,获得界面击溃/侵彻转变速度等参数,以深入探索界面击溃/侵彻转变过程的作用机理(Lundberg 2004; Lundberget al. 2005, 2006). 在界面击溃效应理论研究方面,陶瓷的锥裂纹(Lundberg 2007; Lundberg et al. 2013, 2016)和微观翼型裂纹理论 (LaSalvia 2002a, 2002b, 2005a, 2005b;LaSalvia et al. 2001, 2005, 2007, 2010a, 2010b; LaSalvia & Normandia 2002;LaSalvia & McCauley 2010)是通过靶体的破坏解释界面击溃效应的重要模型.弹体在界面击溃效应中的参数变化主要依靠修正的AT模型获得(Anderson & Walker 2005; 李继承和陈小伟 2011a, 2011b; Li et al. 2014, 2015; Li & Chen 2017).数值模拟作为辅助实验和理论研究界面击溃效应的手段,其关键问题是确定可靠的陶瓷本构模型.学者们采用不同的陶瓷本构模型及参数对影响界面击溃效应的因素进行了数值模拟(Anderson 2006; Anderson et al. 1993b;Holmquist & Johnson 2002a, 2002b, 2003, 2005a, 2005b, 2008, 2011; Holmquist et al. 2001, 2008; Quan et al. 2006; Fountzoulas et al. 2009; Fountzoulas & LaSalvia 2013; Chi et al. 2013, 2015; Serjouei 2014; Yuan et al. 2016; 谈梦婷等 2016). 此外, 从陶瓷的微观结构入手,对界面击溃效应进行数值模拟研究是当今的一大热点.

本文综述了陶瓷界面击溃效应的理论、实验、数值模拟研究,着重介绍陶瓷界面击溃过程中的损伤演化过程,探讨陶瓷界面击溃的影响因素及其作用规律.

2 装甲陶瓷界面击溃效应实验技术

陶瓷界面击溃实验技术包括了实验发射装置和实验观测技术,其中实验观测包括界面击溃作用过程观测及实验后试件的回收观测.国内外学者针对陶瓷的界面击溃效应开展了不同弹靶条件的系列实验研究,包括不同的弹体、陶瓷靶体材料,不同的弹体头部形状与尺寸和不同的装甲结构(裸靶、带盖板、不带盖板、施加预应力、施加约束)等.

2.1 界面击溃效应实验发射装置

陶瓷界面击溃实验通常借助二级轻气炮进行,实验方法主要有直接弹道实验和小尺寸逆向弹道实验, 如图3所示(陈小伟和陈裕泽 2006). 直接弹道实验采用测量侵彻深度(depthof penetration, DOP)方法,通过测量弹体侵彻陶瓷复合靶中金属后效靶的侵彻深度评估陶瓷靶抗侵彻能力.该方法的优点是可以获得真实的弹靶撞击后的结果,避免了尺寸效应对实验结果影响而产生误差. 缺点是信息量少,每次实验只能测得剩余侵彻深度.小尺寸逆向弹道实验通过发射靶体反向撞击弹体,并利用X闪光摄像获得侵彻的时空历程.该方法的优点是获得的实验数据比DOP方法多,可以得到比直接弹道实验方法更清晰的弹靶撞击过程.缺点是只能做小尺寸实验, 无法排除尺寸效应对实验结果产生的影响.Franzen等(1997)关于不同陶瓷小尺寸逆向弹道实验的研究结果表明侵彻深度与长杆弹侵蚀长度的比值在准定常侵彻阶段基本保持为常数,该常数由初始撞击速度决定.

图3   实验测试装置示意图. (a) DOP 实验原理(陈小伟和陈裕泽 2006), (b) 逆向弹道实验装置(Lundberg 2004)

   

Lundberg(2004, 2007), Lundberg等(2000, 2013, 2016),Renström等(2004, 2009), Andersson等(2007), Anderson(2009, 2010), Anderson和 Royal-Timmons(1997), Anderson等(2009, 2011a),Behner等(2011), Orphal(1997), Orphal 和 Franzen(1997)Pickup等 (2002, 2004)采用逆向弹道实验方法对钨合金、金和钼等高密度金属材料长杆弹撞击SiC,B$_{4}$C, Al$_{2}$O$_{3}$等陶瓷材料进行了研究. Crouch等(2015)开展了低碳钢芯撞击碳化硼的实验. 图3(b)为Lundberg研究长杆弹和靶体相撞产生的s界面击溃效应和侵彻现象时采用的实验装置,该装置通过特定发射装置加速陶瓷撞击长杆弹. 图4为长杆弹以一定角度撞击装甲陶瓷的实验装置示意图(Anderson et al. 2011a).

图4   s 长杆弹斜侵彻靶板实验示意图(Anderson et al. 2011)

   

2.2 界面击溃效应作用过程实验观测技术

为了清晰地观测侵彻过程中弹体头部和靶表面破坏情况,学者们采用了高速录像、X光摄影等设备和技术观测了陶瓷靶的界面击溃效应作用过程.Anderson等(2005, 2008, 2011a),采用X光摄影技术对不同角度斜置靶体撞击弹体过程进行了研究.Lundberg等(2000)Westerling等(2001)利用X光摄影技术观测了直径为2mm、长径比分别为40和75的钨合金射弹撞击SiC等陶瓷的界面击溃作用过程,获取了不同陶瓷的界面击溃/侵彻转变速度. 结果表明,陶瓷材料强度及韧性均对界面击溃过程有显著的影响.对陶瓷材料界面击溃现象研究较多的另一团队是来自德国的Ernst-Mach-Institut(EMI)的研究小组(Thoma et al. 2007, Strassburger et al. 2016,Behner et al. 2016), 他们利用先进的多通道X光摄影设备研究了7.62mmAPM2 子弹撞击陶瓷材料时的界面击溃效应(如图5所示),研究了背板材料的影响规律、界面驻留时间以及弹体侵蚀现象,并进行了相关的数值模拟. 实验观测结果表明背板材料强度越大,界面驻留持续时间越长,但该部分工作未能将侵彻速度变化与陶瓷材料力学性能相关联.

图5   EMI侵彻实验观测装置(Strassburger et al. 2016)

   

2.3 陶瓷界面击溃现象及其影响因素的研究

2.3.1 弹体材料及几何形状

为研究杆弹材料对界面击溃效应的作用, Lundberg等(2000), Anderson(2010), Anderson和 Royal-Timmons(1997), Anderson等 (2009, 2011a)和Orphal等 (1996, 1997), Orphal(1997), Behner等(2013)以及Aydelotte 和 Schuster(2015)等分别开展了钨、钼、金等杆弹材料撞击陶瓷靶的界面击溃实验,探讨了弹体性能对界面击溃效应的影响,并发现弹体材料的强度和密度是重要的影响因素.实验研究表明不同头部形状杆弹的界面击溃效应存在差异(Lundberg et al. 2006). 在撞击带缓冲片的陶瓷靶的情况下,平头弹对应的界面击溃/侵彻转变速度高于锥形弹对应的转变速度.对于侵彻不带缓冲片的陶瓷靶, 锥形弹对应的界面击溃/侵彻转变速度更高,约为 1100m/s. 两者差异产生的原因可能是, 侵彻不带缓冲片的陶瓷靶,锥形杆弹在初始时期对靶的作用范围小,靶体内部损伤未有足够时间的累积, 因此靶体不容易被破坏,转变速度较高. 侵彻带缓冲片的陶瓷靶,锥形杆弹在侵彻缓冲片时动能损失少,因此在侵彻陶瓷时更容易对陶瓷产生破坏, 转变速度较低.李继承和陈小伟( 2011a, 2011b)结合流体伯努利方程、AT模型对不同头部形状杆弹在界面击溃过程中速度、长度的变化进行了分析计算.结果表明, 锥形杆弹的动能下降较慢, 且头部锥角越大, 动能下降越明显,该结论与实验观察到的结果相一致.

2.3.2 陶瓷材料

目前,已应用于装甲防护领域的陶瓷材料主要有碳化硅陶瓷、氧化铝陶瓷、碳化硼陶瓷、二硼化钛陶瓷、氮化硼陶瓷以及氧化硼陶瓷等.其中碳化硼陶瓷密度最小、硬度较高, 防护能力最好,是装甲陶瓷材料的首选, 但其制作成本高, 暂时无法广泛应用.与碳化硼相比, 碳化硅成本较低, 是较为理想的装甲材料.其唯一的缺点是抗多次打击能力差,当其在同一位置点遭遇弹体二次撞击时, 其抗弹性能最多能下降70%(宋健 2011). 氧化铝陶瓷密度仅为普通合金钢的一半,同等质量下氧化铝陶瓷的抗弹性能可以达到钢的3$\sim $5倍,成本低、工艺成熟, 是现阶段应用最广泛的装甲材料(满蓬 2012).

Anderson(2007, 2009, 2010), Anderson 和 Morris (1992), Anderson和Royal-Timmons(1997), Anderson等(1995, 2005, 2006, 2009),Lundberg (2004) Lundberg等(2000, 2005, 2006)对多种陶瓷进行了钨合金/金/钼长杆弹的高速撞击实验,研究了侵彻速度、侵彻深度与界面驻留的关系,确定不同陶瓷的界面击溃/侵彻转变速度. 相关研究结果表明陶瓷硬度越高,防护性能越好(Roberson & Hazell 2003, Flinders et al. 2005,Sternberg 1989). LaSalvia等(2010b)通过研究发现一定硬度的陶瓷材料可能使弹体变形并产生界面击溃现象,但不明确硬度对陶瓷材料的界面击溃/侵彻转变过程的作用机理. McCauley和 Wilantewicz(2009)获得了一定范围内SiC的努氏硬度和加载应力的关系.根据Meyer's定律(Meyer 1908)得

$$HK=kF^{c } (1)$$

式中, $HK$为努氏硬度, $F$为加载力,$k$和$c$由$HK$和$F$的关系回归分析可得.

Hilton等(2012)McCauley和 Wilantewicz(2009)关于硬度的研究成果基础上, 将准塑性值与硬度值结合,给出了转变速度与硬度的拟合线性关系如图6所示,得到转变速度与硬度的经验公式, 见式(2).通过压痕实验测得硬度、准塑性参数研究其对界面击溃的作用.存在的问题是硬度测试实验中, 陶瓷硬度随压头尺寸的增加而增加,存在压痕尺寸效应(indentation-size effect, ISE). 此外,压痕实验中产生的损伤也对转变速度有影响,需要开展更深入的研究(Hallam et al. 2015).

$$ TV = 33.59[{\rm Hardness(1N)} + Abs(1 / c)] + 261.42 (2)$$

式中, $TV$为转变速度.

图6   预测不同陶瓷的界面击溃/侵彻转变速度与硬度及塑性的关系(Hilton et al. 2012)

   

2.3.3 陶瓷靶结构

陶瓷作为新型装甲材料,在硬度及密度上具有金属材料不可企及的优异性能. 陶瓷抗侵彻性能突出,其脆性却制约了陶瓷在装甲上的实际应用. Hauver等(1992)最先通过钢/陶瓷/钢结构, 发现界面击溃现象, 如图7所示.

图7   Hauver实验装置示意图(Hauver et al. 1992)

   

Anderson(2009, 2010), Anderson等(2009) Holmquist等(2008)经过实验研究发现, 陶瓷表面带有铜缓冲片时,界面击溃/侵彻转变速度明显增大. 相同时刻, 陶瓷内部应力减小.考虑杆弹撞击靶体时存在位置误差, Behner等(2008) Anderson(2010)对不同尺寸缓冲片的界面击溃效应进行了实验研究,实验结果表明缓冲片大小对界面击溃的影响较小. 另一方面,由于陶瓷的脆性特性,通常采用延展性较好的金属材料作为背板防止陶瓷产生崩落. 为此,Jubin等(2013)研究了界面击溃效应中, 金属背板对能量耗散的影响规律,结果表明能量耗散与界面驻留时间呈线性关系,高强度、高韧性的背板材料可以增加界面击溃时的能量耗散.金属/陶瓷/金属结构是一种常见的陶瓷复合靶结构.实验研究结果表明陶瓷与背板之间的吸能层可以有效提高装甲的防护能力(Rabiei 2014, Feli & Asgari 2011, Garcia-Avila et al. 2014). 近来,北卡罗莱纳州立大学Garcia-Avila等(2014)利用碳化硅陶瓷作为靶体打击外层,粉末冶金加工的复合金属泡沫作为吸收子弹动能的吸能中间层,铝或凯夫拉(Kevlar)作为背板层的复合靶结构, 如图8所示,装甲总厚度小于25mm. 实验研究采用7.62mm$\times$51mmM80步枪子弹和7.62mm$\times$63mm M2穿甲弹进行弹靶撞击实验,撞击速度在850m/s左右, 实验中产生了明显的界面击溃效应. Behner等(2016)最新研究表明,陶瓷在实验尺寸条件下没有径向约束也可以获得界面击溃效应,或短暂的界面驻留过程, 同时,陶瓷表面的缓冲片可以缓解冲击作用并提高转变速度,最佳的缓冲片厚度为弹体直径的一半.

图8   北卡罗莱纳州大学的陶瓷复合装甲侵彻实验(Garcia-Avila et al. 2014)

   

Lundberg等(2006)研究了约束条件对陶瓷界面击溃的影响.通过陶瓷锥裂纹模型揭示了陶瓷由界面击溃向侵彻转变与断裂韧性和约束应力的关系.约束产生的预应力越大, 陶瓷能够承受的弹体加载的压力越大. 此外,实验研究表明在一定范围内, 约束应力越大, 转变速度越高.约束应力继续增大时, 转变速度并不会增大. Hauver等(2005)Anderson等(2011a)通过实验获得了钨合金/金制长杆弹斜侵彻陶瓷靶的界面击溃、侵彻及其转变过程,并获得了不同弹靶条件下的转变速度,其中斜侵彻靶的转变速度与正侵彻相比较高,表明斜侵彻可以提高靶体的抗弹性能.

2.3.4 尺度效应

Lundberg等(2013)Holmquist等(2010)Behner等(2011)等学者通过实验研究发现相同的弹靶材料, 靶体尺寸越大,界面击溃/侵彻转变速度越低, 陶瓷靶越容易被侵彻. 同时, 实验表明,小尺寸的陶瓷裸靶与大尺寸带约束的陶瓷靶产生界面击溃的能力与抗侵彻能力相似,这表明陶瓷的界面击溃效应存在尺度效应. Lundberg等(2013)为此开展了陶瓷界面击溃的理论计算和实验研究, 如图9所示.理论计算表明陶瓷界面击溃/侵彻转变速度与尺寸的1/2次方成反比,这与实验中尺寸越大, 界面击溃/侵彻转变速度越小的结果相一致, 如图10所示. 因此, 将陶瓷靶体应用于实际时,需要考虑弹靶尺度效应的影响.

图9   界面击溃尺度效应实验实验装置示意图(Lundberg et al. 2013)

   

图10   Lundberg实验结果. (a) 转变速度$v_{\rm p}$和(b)界面击溃/侵彻转变时对应的弹体应力$p_{0}$与弹体尺寸--半径$a$的关系,实线为理论计算结果, 虚线分别为拉伸失效(TF),初始塑性屈服(IY)和完全塑性屈服(FY)的边界情况(Lundberg et al. 2013)

   

3 装甲陶瓷界面击溃效应理论研究

Hauver等(1994)通过大量实验发现TiB$_{2}$在界面击溃过程中,撞击区域的正下方出现大片粉碎区域, 另有锥形裂纹从陶瓷表面开始扩展,如图11所示. 目前关于陶瓷界面击溃理论的研究工作可分为三类:一是从宏观陶瓷锥入手研究界面击溃/侵彻转变速度与弹靶表面压力的关系(Lundberg 2004, 2007; Lundberg et al. 2000, 2013, 2016; Renström et al. 2004, 2009; Andersson et al. 2007)以及撞击表面下锥裂纹的形成和扩展对界面击溃的影响;二是基于微观翼型裂纹扩展模式研究轴向应力与界面击溃/侵彻转变速度的关系(LaSalvia 2002a, 2002b, 2005a, 2005b; LaSalvia et al. 2001, 2010b; LaSalvia & McCauley 2010),结合翼型微裂纹与塑性区域的产生对界面击溃现象进行研究;三是基于AT模型研究不同头部形状长杆弹在界面击溃条件下的动能变化(Anderson & Walker 2005; 李继承和陈小伟 2011a, 2011b; Li et al. 2014, 2015; Li & Chen 2017).

图11   SiC陶瓷内部损伤形态. (a)WC破片撞击时,SiC内部产生的裂纹(Iyer 2007); (b)界面击溃时, TiB$_2$内裂纹情况(Hauver et al. 1994)

   

3.1 界面击溃/侵彻转变过程力学机制

国内外学者对装甲陶瓷的界面击溃/侵彻转变过程的力学机制进行了多方面的假设与分析.回收界面击溃、侵彻实验后的靶体试件可以观测到靶体在撞击作用下产生大量的微观裂纹和锥裂纹,如图11所示(Hauver et al. 1994). 因此,大部分研究认为界面击溃/侵彻转变过程是由于靶体内部产生裂纹使靶体的抗侵彻能力下降所致.Lundberg(2004)Lundberg等(2000, 2013, 2016)认为当弹靶表面压力超过临界值时, 陶瓷由界面击溃向侵彻现象转变,该临界值主要受陶瓷内部锥裂纹的影响. LaSalvia等(2001)LaSalvia(2002a)认为陶瓷在撞击过程中产生的微观翼型裂纹是导致界面击溃向侵彻转变的主要原因.Zhang等(2017)谈梦婷等(2017)结合翼型裂纹和锥裂纹扩展理论建立了界面击溃条件下陶瓷材料的损伤演化模型,包括表面压力分布、陶瓷内部应力状态、微观裂纹扩展以及宏观锥裂纹的扩展过程.Uth 和 Deshpande(2013)认为弹靶作用过程可看作是流动的弹体和变形体靶之间的流固耦合(fluid-structure interaction, FSI) 问题,界面击溃向侵彻转变的原因是靶体变形导致弹体反向流动,两者作用下弹靶接触力增大, 使得靶体被侵彻, 如图12所示.弹体的反向流动的速度和角度与靶体表面的初始开坑相关联.陶瓷作为脆性材料, 初始开坑可能与损伤累积相关,陶瓷靶体结构将对侵彻速度有较大的影响.

图12   界面击溃/侵彻过程的流固耦合机制. (a)界面击溃时,靶体为平面,弹体径向流动; (b)侵彻时, 弹体成一定角度反向流动

   

3.2 界面击溃过程中弹体参数变化

长杆弹撞击装甲陶瓷界面击溃时,弹体材料在陶瓷表面径向流动可视为是流体材料. Alekseevski(1966)Tate(1967)根据长杆弹对陶瓷靶的高速侵彻特征,在呈半流体状的弹靶界面区域, 给出修正的Bernoulli方程如下

$$ \dfrac{1}{2}\rho _{\rm p} \left( {\upsilon - \mu }\right)^2 + Y_{\rm p} =\dfrac{1}{2}\rho _{\rm t} \mu ^2+R_{\rm t} (3)$$

$$ \rho _{\rm p} l '\dfrac{{\rm d}\upsilon }{{\rm d}t} =- Y_{\rm p} (4)$$

$$ \dfrac{{\rm d}l'}{{\rm d}t} = - \left( {\upsilon -\mu } \right) (5)$$

$$ \dfrac{{\rm d}P}{{\rm d}t} = \mu (6)$$

式(3)$\sim $式(6)中, $\rho _{\rm p}$和$\rho _{\rm t}$分别为弹体材料密度和靶体密度, $Y_{\rm p}$为弹体材料流动应力,$R_{\rm t}$为靶体侵彻阻力, $\mu $, $\upsilon $, $P$,$l$分别为侵彻速度、弹体速度、侵彻深度和弹体长度, $t$为时间.

李继承和陈小伟 ( 2011a, 2011b)在AT模型的基础上,阐述了不同头部形状长杆弹在界面击溃条件下速度、长度、动量变化规律.理论计算结果表明, 陶瓷界面击溃过程中,速度下降引起的动能损失远小于质量侵蚀引起的动能损失, 如图13所示. 对于靶体斜侵彻问题, Li 和 Chen(2017)认为长杆弹在斜侵彻下撞击特点与正侵彻区别较大,杆弹弹体参数随之变化.研究得到的结论是斜侵彻对界面击溃的作用大于盖板.该理论模型主要针对大尺寸的靶体,未考虑尺寸以及约束等其他影响因素对界面击溃的作用.

图13   不同头部形状长杆弹界面击溃过程中弹体参数变化情况. (a)不同头形长杆弹的相对质量变化曲线, (b)不同头部形状长杆弹的相对动能变化曲线(李继承和陈小伟 2011a)

   

3.3 弹靶表面压力分布

Lundberg等(2000) 建立的界面击溃时陶瓷表面压力分布模型如图14所示.

图14   界面击溃过程中, 陶瓷表面压力分布(Lundberg et al. 2000)

   

模型假设界面击溃过程中, 弹体是理想弹塑性体, 陶瓷靶体为线弹性体,弹靶接触为准静态过程, 忽略弹靶接触初期的应力瞬变现象(Lundberg et al. 2000). $z$轴方向的运动方程为

$$ \dfrac{\partial \sigma_{{zz}} }{\partial z} + \dfrac{1}{r}\dfrac{\partial }{\partial r}\left( {r\sigma _{rz} } \right) = \rho \left( {v_r\dfrac{\partial v_z }{\partial r} + v_z \dfrac{\partial v_z}{\partial z}} \right) (7)$$

式中, $\rho $, $v$和$\sigma$分别表示密度、速度和应力.

由于弹体材料是完全塑性实体,因此满足Von-Mises屈服准则和关联流动法则

$$\left.\begin{array}{l} d_{rz} = \dfrac{1}{2}\left( {\dfrac{\partial v_r}{\partial z} + \dfrac{\partial v_z }{\partial r}} \right)\\\left| \pmb d \right| = \sqrt { d _{ij} d _{ij} } = \sqrt{\left(\dfrac{\partial v_r }{\partial r}\right)^2 + \left(\dfrac{\partial v_z }{\partial z}\right) ^2 + \left(\dfrac{v_r}{r}\right)^2 + 2\left(\dfrac{\partial v_r }{\partial z} +\dfrac{\partial v_z }{\partial r}\right)^2}\\ \sigma _{rz} =\dfrac{\sqrt 6 }{3}\sigma _{\rm yp} \dfrac{{\rm d}_{rz}}{\left|\pmb d\right|} \end{array}\right\} (8)$$

式中, $d$是变形张量, $\sigma _{\rm yp}$为弹体材料屈服强度.

根据连续介质力学运动方程和Von-Mises屈服准则, Lundberg等(2000)得出了弹靶表面最大压力与弹体体积模量、密度、撞击速度及弹体屈服强度的关系表达式为

$$ v_{\rm p} = \sqrt {\dfrac{2K_{\rm p} }{\rho _{\rm p} }\left(\sqrt {1 +\dfrac{2(P_0 - 3.27\sigma _{\rm yp} )}{K_{\rm p} }} - 1\right)} (9)$$

式中, $v_{\rm p}$为弹体速度, $\rho _{\rm p}$为弹体材料密度, $K_{\rm p}$为弹体材料体积模量,$P_{0}$为弹靶表面最大接触应力.

在计算过程中, Lundberg等(2000)采用水流在靶体表面形成的归一化应力分布规律近似代替弹靶撞击时的弹靶表面压力分布.通过Boussinesq方程和撞击作用下获得的滑移线方程求解得出了界面击溃/侵彻转变速度的上下边界,即式(10).

$$ (1.30 + 1.03\nu )\sigma _{\rm y} \leq p_0 \leq 2.85\sigma _{\rm y} (10)$$

式中, $\nu $为靶体材料泊松比, $\sigma _{\rm y}$为靶体材料屈服强度.

Lundberg等(2000)开展了系列长杆弹撞击装甲陶瓷的实验研究,并对基于陶瓷锥的损伤破坏模型进行了验证,实验结果表明陶瓷表面压力分布模型可以较好地预测界面击溃/侵彻转变速度的上下限.该模型还应用于研究弹体屈服强度、压缩特性、弹体的惯性效应在界面击溃过程中对弹靶接触表面压力的影响.在装甲设计对界面击溃效应的影响方面, Lundberg等(2016)研究了外加约束对陶瓷内部应力及界面击溃/侵彻转变过程的作用.

此外, Li等(2015)在Lundberg关于陶瓷压力分布模型的基础上深入分析转变过程,重新定义了陶瓷界面击溃时最大表面接触应力的极限值.他认为陶瓷类脆性材料, 当撞击压力小于雨贡紐弹性极限 $\sigma _{\rm HEL}$时, 陶瓷内部只有弹性形变, 换而言之, 只有压力超过 $\sigma_{\rm HEL}$时, 损伤或失效才开始产生. 因此,用于计算界面击溃/侵彻转变速度的$P_{0}$可以限定为 $\sigma _{\rm HEL} \leq P_{0} \leq 2.85 \sigma _{y}$,在此基础上获得了界面击溃/侵彻转变速度和时间的表达式.

Uth 和 Deshpande(2013)综合分析了现有的界面击溃理论模型,认为其存在的缺陷有: (1)当SiC, WC和B$_{4}$C都存在界面击溃效应时,SiC中存在微裂纹导致的粉碎区域, 但在WC和B$_{4}$C中并不存在该区域.因此, 现有的界面击溃理论模型无法适用于所有陶瓷材料; (2)微裂纹产生的时间较短, 在1$\mu $s左右(Bourne 2010),界面击溃时间可能达几百微秒, 推测微裂纹的形成阶段可以忽略(Lundberg 2004, Andersson et al. 2007); (3) 研究中一般认为界面击溃过程中,弹体侵彻速度为0, 实验表明在界面击溃过程中, 侵彻速度不为0,靶板会被侵彻或推动(Subramanian & Bless 1995). Renström等(2004)通过研究发现在高速冲击下, 弹体可视为流体对陶瓷靶产生冲击,借鉴流固耦合机制在三明治靶板中的成功应用(Wadley et al. 2013, Liu et al. 2013),可以将弹靶界面击溃问题演变成流体弹与变形体靶之间的流固耦合问题.文中采用了水流撞击柔软透明的高真空润滑脂材料类比观察陶瓷与弹体之间的界面击溃与侵彻现象,如图15所示.采用尺寸相似模型的优点是可以清楚地观测界面击溃效应.

图15   水流撞击高真空润滑脂类材料(Uth & Deshpande 2013)

   

3.4 陶瓷锥裂纹模型

陶瓷破坏的初始阶段出现锥裂纹,裂纹从陶瓷表面开始产生并向陶瓷内部发展. Lundberg(2004)、Lundberg等(2000, 2013)从20世纪初开始研究界面击溃过程中陶瓷内部损伤扩展,建立了基于陶瓷内部锥裂纹扩展的材料损伤破坏模型.为简化问题作如下假设: (1) 裂纹沿主应力方向传播, 忽略其他类型裂纹;(2) 裂纹的径向延伸由断裂韧性$K_{\rm IC}$决定; (3)界面击溃为准静态过程. 模型示意图如图16所示,模型中计算了裂纹尖端应力大小和陶瓷材料的临界应力,用于判断界面击溃/侵彻现象并预测了转变速度.

图16   锥裂纹模式下的界面击溃(Lundberg et al. 2013)

   

裂纹尖端主应力 $\sigma _{1}(r)$表达式为

$$ \sigma _1 (r) = \sigma_{rr} (r,z_1 (r))\sin ^2\theta - 2\tau _{rz} (r,z_1 (r))\sin\theta \cos \theta + \sigma _{zz} (r,z_1 (r))\cos ^2\theta (11)$$

式中, $\sigma _{rr}$为径向应力, $\tau _{rz}$为剪切应力, $\sigma _{zz}$为轴向应力, $r$为径向距离, $z$为轴向距离,$\theta $为裂纹扩展法向与径向轴线的夹角.

材料临界应力 $\sigma _{\rm c}$表达式为

$$\sigma _{\rm c} = \dfrac{K_{\rm IC} }{p_0 \sqrt {a\pi c} } (12)$$

式中, $K_{\rm IC}$为陶瓷材料断裂韧性, $a$为弹体半径,$c$为裂纹长度.

陶瓷界面击溃锥裂纹模型的理论计算结果表明: 在弹靶条件相同的情况下,界面击溃/侵彻转变速度随弹体半径的增加而减小(Lundberg et al. 2013).Lundberg等(2013)建立的关于界面击溃效应的陶瓷锥模型,可以较好地预测界面击溃/侵彻转变速度, 对靶体设计具有指导意义.Jaansalu(2013)在锥裂纹模型的基础上研究了材料弹性极限、形状、撞击压力对界面击溃的影响,优化了界面击溃/侵彻转变速度的计算模型.

3.5 靶体内部翼型裂纹扩展模型

陶瓷等脆性材料在微观状态下存在原生裂纹等缺陷.陶瓷内部原生裂纹在压缩载荷作用下在材料内部扩展, 演变成翼型裂纹,发展为塑性变形.翼型裂纹扩展模型建立在脆性材料压缩失效模型的基础之上.陶瓷内部翼型裂纹扩展使陶瓷材料剪切失效,当失效区域到达弹靶接触表面时, 陶瓷材料破坏, 弹体开始侵彻靶体.翼型裂纹扩展模型主要研究了转变速度与延性系数、泊松系数与摩擦系数等靶体材料特性的关系.脆性材料压缩失效模型, 如图17所示,假设原生裂纹$PP'$通过剪切作用在其尖端产生翼型裂纹$PQ$,$P'Q'$与塑性区$PO$, $P'O'$, 长度分别为$l_{\rm t}$和$l_{\rm p}$(LaSalvia 2002a, LaSalvia & McCauley 2010).翼型裂纹扩展方向与原生裂纹的夹角为$\theta $, $\mu $为摩擦系数.在微裂纹的相互作用下, 最终形成宏观裂纹导致材料失效.

图17   脆性材料压缩失效翼型裂纹扩展模型示意图(LaSalvia 2002a)

   

不考虑温度和应变率的情况下,脆性材料的压缩失效机制主要包括轴向分裂和原生缺陷(Horii & Nemat-Nasser 1986). 在压缩作用下,脆性材料内部的原生裂纹由剪切作用向外扩展, 并发展成为翼型裂纹.LaSalvia等(2001)在Horii、Nemat-Nasser的翼型裂纹模型的基础上,从陶瓷内部微裂纹扩展理论入手,研究陶瓷硬度、泊松系数、摩擦系数、剪切强度等靶体材料属性与界面击溃/侵彻转变速度的关系.断裂韧性表达式为

$$\varDelta =\dfrac{K_{\rm IC} }{\tau _{\rm Y}\sqrt {\pi c} } = \dfrac{\left( {\dfrac{\sigma _1 }{\tau _{\rm Y} }} \right)\left[ {\left( {1 - \dfrac{\sigma _2 }{\sigma _1 }}\right) - \mu \left( {1 + \dfrac{\sigma _2 }{\sigma _1 }} \right)- \sqrt 2 \pi \left( {\dfrac{\sigma _2 }{\sigma _1 }}\right)\left( {\sqrt {\dfrac{l_{\rm t} }{c}} } \right)^2}\right]}{\sqrt 2 \pi \sqrt {\dfrac{l_{\rm t} }{c}} } (13)$$

$$ \dfrac{\sigma _1 }{\tau _{\rm Y} } = - \dfrac{2\left\{ {1 - \left( {\dfrac{2}{\pi }}\right)\sin ^{ - 1}\left[ {1 / \left( {1 + \dfrac{l_{\rm p}}{c}} \right)} \right]} \right\}}{\left( {1 - \dfrac{\sigma _2}{\sigma _1 }} \right) - (2\mu / \pi )\left( {1 + \dfrac{\sigma_2 }{\sigma _1 }} \right)\sin ^{ - 1}\left[ {1 / \left( {1 +\dfrac{l_{\rm p} }{c}} \right)} \right]} (14)$$

式(13)$\sim $式(14)中, $\varDelta $为延性系数, $\varDelta=K_{\rm IC}/[\tau _{\rm Y}(\pi c)^{1/2}]$,代表材料在压缩作用下脆性失效强度与韧性失效强度的比值, 其中 $\tau_{\rm Y}$是陶瓷的剪切强度, $\sigma _{1}$和 $\sigma _{2}$为主应力.

界面击溃过程中, 陶瓷材料内部的原生裂纹在弹体的撞击作用下,产生剪切应力导致裂纹向外扩展,最后裂纹形成的塑性区域到达陶瓷表面使损伤的陶瓷成为没有约束的自由面.此时, 杆弹开始侵彻陶瓷. 在求解翼型裂纹尖端应力时, LaSalvia(2002a)主要采用了Hertz接触理论(Johnson 1987, Fischer-Cripps 2010),对轴线上的翼型裂纹扩展进行了分析. 利用Hertz接触理论,获得陶瓷轴线方向上压力分布关系式为

$$ \dfrac{\sigma _1^{\rm H} }{p_0 } = - \dfrac{1}{1 + \left({z / a} \right)^2} (15)$$

$$ \dfrac{\sigma _2^{\rm H} }{p_0 } = \dfrac{\sigma _3^{\rm H} }{p_0} = - \left( {1 + \nu } \right)\left[ {1 - \left( {\dfrac{z}{a}}\right)\tan ^{ - 1}\left( {\dfrac{a}{z}} \right)} \right] +\dfrac{1}{2\left[ {1 + \left( {z / a} \right)^2} \right]} (16)$$

$$ \dfrac{\tau ^{\rm H}}{p_0 } = \dfrac{1}{2}\left| {\left( {1+ \nu } \right)\left[ {1 - \left( {\dfrac{z}{a}} \right)\tan ^{ -1}\left( {\dfrac{a}{z}} \right)} \right] - \dfrac{3}{2\left[ {1 +\left( {z / a} \right)^2} \right]}} \right| (17)$$

式(15)$\sim $式(17)中$a$为弹靶接触半径.

联立上式可得$P_{\rm m}$与延性系数$\varDelta $, 泊松系数$\nu $,陶瓷剪切屈服强度的关系为

$$ P_{\rm m} =\dfrac{\sqrt 2 \pi \varDelta \tau _{\rm y} }{3\left( {1 - 2\nu }\right)\left( {1 - 1.154\varDelta } \right)\sqrt {1 - R^2} } (18)$$

LaSalvia(2002a)建立的界面击溃模型采用Hertz接触理论获得轴线上的应力分布,进而建立陶瓷撞击区域轴线上裂纹分布以及粉碎区形成的模型.该理论模型存在两方面的不足,一方面翼型裂纹模型采用了对弹性体适用的Hertz接触理论,假设与实际情况存在差异. 另一方面,翼型裂纹模型主要用于假设裂纹的尺寸大于晶粒尺寸的现象,并不一定与实际现象对应. 此外,模型只考虑单一的轴线方向翼型裂纹模型,这与实际观测中发现陶瓷损伤区域存在多种裂纹分布不相符.

4 陶瓷界面击溃效应数值模拟

数值模拟是研究一种物理现象本质的工具之一.国内外学者大多采用LS-DYNA或AUTODYN等有限元软件对陶瓷界面击溃进行数值模拟,辅助界面击溃的实验和理论研究工作.数值模拟在深入了解陶瓷侵彻过程、精确分析影响因素对陶瓷界面击溃的作用和预测陶瓷材料在未来假定条件下的响应方面具有优势.数值模型的一部分建立在实验基础之上,其准确性与可靠性是其实用性的重要标准. 因此,发展陶瓷材料界面击溃效应的数值模拟,完善其精准性是未来开展界面击溃研究、设计高性能陶瓷复合装甲工作的关键.

4.1 陶瓷的本构模型

界面击溃效应是陶瓷在大应变、高应变率和高温高压下的一种动态响应过程.陶瓷材料本构及损伤模型是开展陶瓷界面击溃效应及冲击破坏过程数值模拟计算的基础.相关研究结果表明, 在准静态情况下,基本可以假定陶瓷材料是线弹性体直至材料破碎, 与损伤无关(Chen 1995).陶瓷在高速撞击过程中产生损伤破坏, 部分破坏的陶瓷,甚至完全破碎的材料力学性能都对抗侵彻过程有十分重要的影响,因此建立考虑损伤的本构模型对陶瓷的界面击溃效应、抗侵彻机理研究及装甲陶瓷的设计至关重要.目前大多数陶瓷材料的本构关系都建立在连续介质力学及损伤理论的基础上.国内外许多学者对此进行了研究, 并将其应用于各类软件中,主要的陶瓷材料本构模型有以下几类.

4.1.1 Wilkins陶瓷模型

Wilkins陶瓷模型是基于材料拉伸失效的模型,通过模拟冠状裂纹的发展获得陶瓷材料本构关系(Wilkins 1963).当模型中一个单元内最大主应力超过最大拉伸应力时, 材料出现断裂.材料开始断裂后, 随着载荷的增大, 裂纹在单元内以剪切波速度传播,在有限时间内, 全部单元产生裂纹. 在此失效准则下, 陶瓷将很快失效,因此需要参照其他失效准则.另一个裂纹准则是单元的初始裂纹只在单元表面或紧邻的陶瓷单元完全破裂的情况下产生.在此情况下, 损伤以裂纹形式传播, 传播速度是剪切波速度的一部分.此外, 当拉伸应力小于拉伸应力准则时, 裂纹停止传播.

McGlaun等(1990)和Walker 和 Anderson(1991)将Wilkins陶瓷模型应用于CTH代码的中,模拟了7.62mm穿甲弹撞击7.62mm厚B$_{4}$C陶瓷过程,陶瓷采用 6061-T6铝作为基底,得到该陶瓷的弹道极限速度为820m/s并观察了陶瓷内部断裂锥形体的变化.Wilkins模型最初未考虑材料完整性与强度的关系,引入Drucker-Prager模型后,Wilkins模型弥补了失效的陶瓷材料没有强度的缺陷. 然而,在实验数据的重现、冲击失效情况下的剩余速度的预测、材料界面击溃效应的准确预测等方面,Wilkins模型仍存在缺陷.

4.1.2 Rajendran-Grove (RG)模型

RG模型是基于微观力学发展而来,该模型中材料的弹性常数随着损伤的累积而减小(Rajendran 1994,Rajendran & Grove 1996).损伤值通过测量无量纲化的微裂纹密度确定.微裂纹的演化规律是以单个裂纹在动态加载情况下为基础,根据断裂力学推导而出的.

RG模型的另一个内容是陶瓷“软化”(弹性常数劣化)方程.该方程是关于微裂纹量纲密度的函数, 当损伤到达临界值时,陶瓷材料完全失效. 陶瓷粉碎前, 该模型允许微孔塌陷,以考虑孔隙周围基体材料的局部微塑性流动导致压缩过程中完整陶瓷初始孔隙率的变化.RG模型最初的目的是研究飞片实验的冲击波传播过程,后被应用于侵彻过程研究(Rajendran 1994).

4.1.3 Johnson-Holmquist (JH)模型

JH模型(Johnson & Holmquist 1992, 1994; Holmquist & Johnson 2005a, 2005b, 2011)是现今计算机数值模拟研究领域应用范围最广的陶瓷本构模型,主要通过陶瓷材料的破坏现象确定材料本构参数.该模型假设材料在屈服面产生非弹性应变, 该应变是关于压力的函数.通过JH模型可以得出材料在完整和失效两种状态下压力、应变率与等效应力的函数关系,而损伤累积可由塑性应变确定. 损伤$D$可以表示为

$$ D=\sum\Delta \varepsilon _{\rm p}\Big/\varepsilon _{\rm p}^{\rm f} (19)$$

式中, $\Delta \varepsilon _{\rm p}$ 为塑性应变增量, $\varepsilon_{\rm p}^{\rm f}$ 为与压强相关的失效应变

$$\varepsilon _{\rm p}^{\rm f}=\phi(P+T) (20)$$

式中, $\phi$ 为损伤系数.

状态方程中压强可以表示为

$$ P=K_1\mu+K_2\mu^2+K_3\mu^3+P_{\rm dil} (21)$$

式中, $\mu=\rho/\rho_0-1$, $P_{\rm dil}$为材料膨胀引起的压力变化.

JH-1模型是Johnson 和Holmquist(1992)建立的第一个关于脆性材料的本构模型.该模型考虑了材料的大变形, 但没有考虑变形扩大导致的损伤累积,采用线性分段函数描述脆性材料的压力强度关系、损伤和应变率效应.JH-2模型是在JH-1模型的基础上发展而来. JH-2模型(Johnson & Holmquist 1999)用无量纲解析方程描述了应力和强度的关系,材料强度随损伤的累积而逐渐降低.该本构主要用于描述陶瓷等脆性材料在大变形、高应变率以及高压下的强度、应变率效应及损伤劣化等力学行为.状态方程是考虑了应变率、静水压力以及损伤相关的强度模型的多项式.JH-2模型是在JH-1模型基础上,加入强度的连续损伤劣化效应来描述材料的梯度破坏过程.脆性材料在加载过程中首先表现为弹性变化,当应力水平达到材料的屈服极限时, 材料开始产生损伤.随着材料内部损伤逐渐累积, 脆性材料发生劣化, 最终完全破碎.该模型参数主要通过MTS拉压实验,Hopkinson杆拉压实验、飞片冲击实验与DOP弹道侵彻实验确定. Leavy等(2008)采用新的试验技术确定JH-1本构参数,所得参数应用于球形破片冲击实验的数值模拟, 其结果与实验结果相吻合.JH-1和JH-2模型主要分强度、损伤和应力三部分, 如图18所示.文献表明, JH-1对SiC陶瓷材料的动态响应过程描述更为合理(Holmquist & Johnson 2002a). Templeton等(2002)、 Holmquist 和Johnson ( 2002a, 2002b)以及Quan等(2006)使用JH-1模型对B$_{4}$C与SiC陶瓷进行了长杆弹撞击陶瓷界面击溃效应进行了数值模拟,计算结果与实验结果吻合较好,并对不同弹靶条件下的界面击溃或侵彻现象进行了预测.谈梦婷等(2016)在Quan的工作基础上,对不同头部形状长杆弹、盖板厚度以及预应力进行了数值模拟研究.Serjouei(2014)采用JH-2模型对弹体撞击陶瓷靶体时的界面击溃、侵彻以及界面击溃/侵彻转变过程进行了数值模拟.为了适应Al$_{3}$N$_{4}$在高应变、高应变率及高压下的相变特性,Johnson等(2003)在JH-2模型的基础上, 加入了相变特性, 得到JHB模型.Fountzoulas等(2009), Fountzoulas和LaSalvia(2013)采用JH-2模型开展了杆弹撞击B$_{4}$C陶瓷界面击溃效应的数值模拟.数值模拟结果表明标准的JH-2模型参数无法准确描述界面击溃过程中裂纹分布,未来的工作还需要更为具体的弹靶参数.

图18   JH-1和JH-2模型中应力、应变和压强的关系. (a) JH-1, (b) JH-2

   

4.1.4 Deshpande-Evans(DE)模型

Deshpande-Evans (DE)模型不同于JH等唯象学模型, 是基于Ashby(Ashby & Hallam 1986; Ashby & Sammis 1990)建立的翼型裂纹扩展模型发展而来,用于描述陶瓷中非弹性形变和断裂的本构模型(Deshpande & Evans 2008). 模型主要包括4个特征:(1)基于应力强度和裂纹扩展规律的微裂纹扩展率;(2)裂纹密度包括裂纹闭合对刚度的影响; (3) 高约束压力下的塑性;(4)晶粒大小时的原生裂纹.模型可以通过预测不同应力状态下的应力/应变响应获得三向应力较小时的微裂纹扩展向三向应力较大时的塑性滑移转变的过程,包括微裂纹作用下的膨胀机制. 三向应力增大,损伤陶瓷的剪切强度也增大. 冲击破坏机制主要研究了3个方面:(1)准静态压缩, 应力导致裂纹扩展至陶瓷表面, 陶瓷破坏;(2)中等撞击速度,由于弹性波的反射在陶瓷内部产生的拉伸和压缩应力造成陶瓷损伤;(3)高速撞击, 内表面塑性损伤、外表面由应力波拉伸作用产生的碎片崩落.空腔应力在准静态作用下对晶粒大小敏感, 在动态加载作用下不敏感.该模型可以有效地观测陶瓷在准静态和动态加载下内部裂纹扩展情况(如图19所示), 是解释界面击溃的重要手段.现阶段的研究仍停留在陶瓷的准静态破坏及球形破片撞击陶瓷的数值模拟阶段,还未开展子弹及长杆弹高速撞击陶瓷靶的情况.DE模型可以从物理本质上反应陶瓷材料动态力学响应,但现阶段的DE本构对数值模拟条件要求高, 未能广泛应用, 值得深入研究.

图19   采用DE模型的钢球撞击Al$_{2}$O$_{3}$数值模拟与实验结果对比(Deshpande et al.2011)

   

4.2 陶瓷界面击溃影响因素的数值模拟研究

4.2.1 陶瓷约束

陶瓷的约束一般考虑轴向和径向两个方向, 轴向约束主要为缓冲片及盖板,径向约束一般在陶瓷外围的金属环. Dehn(1996)提出随着陶瓷厚度的增大,在高速冲击载荷作用下, 需要考虑陶瓷内部波动造成的损伤破坏.同过采用HULL代码进行数值模拟,结果表明合适的约束可以产生界面击溃效应. Grove 和 Rajendran(2001)采用了RG陶瓷本构模型对约束陶瓷的界面击溃效应进行了数值模拟,并验证了RG模型研究陶瓷材料动态响应的可行性. Simha等(2002)由杆动态撞击和飞片实验获得了陶瓷的本构参数并使用EPIC代码对陶瓷的侵彻和界面击溃进行了数值模拟,研究结果表明: 盖板的材料、形状和撞击速度会影响界面击溃效应.Fountzoulas和LaSalvia(2012)在EPIC代码中采用JHB模型对有铜缓冲片、大尺寸缓冲片及无铜缓冲片的SiC靶进行了高速撞击的数值模拟,结果表明缓冲片有助于产生界面击溃, 提高界面击溃/侵彻转变速度; 此外,厚盖板惯性效应使弹体碎片沿盖板/陶瓷表面流动对盖板产生破坏.Fountzoulas和LaSalvia(2011)对LaSalvia的实验进行了数值模拟,并未获得与实验类似的界面击溃现象.推测是由于约束使失效陶瓷的强度高于原本构模型中的失效强度,导致实验和数值模拟误差的产生,更加表明了数值模拟的可靠度取决于材料模型及合适的材料参数,Normandia(2004)对不同SiC陶瓷的数值模拟得到了相同的结论. Yuan等(2016)在Autodyn软件中对含铜缓冲片的陶瓷靶和径向预应力的陶瓷靶体进行了数值模拟,结果表明与径向预应力相比, 铜缓冲片更能在高速下产生界面击溃.径向预应力可以提高陶瓷强度,但无法改变应力分布及消除弹体边缘损伤的产生.缓冲片可以扩大表面压力作用范围, 增大陶瓷的局部静水压和陶瓷强度,阻止弹靶接触面损伤的产生. Malaise等(2000)将弹封装进PC中,使其对陶瓷产生“动态约束”, 并将该过程用欧拉OURANOS进行数值模拟,结果表明破碎陶瓷的响应是研究陶瓷界面击溃效应的关键. Partom(2011)运用了脆性剪切失效模型对不加盖板和加盖板陶瓷的冲击损伤进行了数值模拟,验证了剪切失效模型的可靠性,并通过观察发现加盖板陶瓷比不加盖板陶瓷的界面击溃/侵彻转变速度提高了约400m/s.

4.2.2 预应力效应

破碎陶瓷和完整陶瓷的强度与压力相关,给陶瓷施加预应力从理论上可以提高陶瓷强度. Holmquist 和 Johnson( 2003, 2005a, 2005b, 2008) (如图20所示)、Serjouei等(Serjouei 2014, Serjouei et al. 2016)和Chi等(2013, 2015)等开展的预应力陶瓷界面击溃效应仿真模拟研究工作,通过数值模拟获得了界面击溃效应并验证了预应力可以提高陶瓷性能的可行性.

图20   预应力陶瓷的仿真(Holmquist & Johnson 2005)

   

Savio等(2011)关于小口径弹体侵彻预应力陶瓷的研究表明,预应力可以减少裂纹及损伤在陶瓷内部的产生. Holmquist 和 Johnson(2003)进行了预应力陶瓷的数值模拟,研究了靶体厚度、预应力大小以及预应力状态对弹道性能的影响.结果表明, 较高的初始应力对接触应力变化历程影响较小,靶体的中心位移显著减小. 综上所述,提高预应力能提高陶瓷的强度与韧性、减少陶瓷材料拉伸失效行为,进而提高陶瓷靶的抗弹性能.

4.2.3 陶瓷复合靶结构

为弥补陶瓷脆性的缺陷, 装甲设计中陶瓷常以复合装甲的形式出现.传统的陶瓷复合装甲一般采用金属/陶瓷/金属的结构.表面金属消耗弹体动能, 陶瓷作为中间层侵蚀弹体,背面辅以金属材料吸收弹体动能. 现阶段利用界面击溃效应,复合装甲采用陶瓷作为迎弹面侵蚀弹体, 泡沫金属作为中间层,铝/kevlar等韧性材料作为背面.泡沫金属材料是在金属基底中填入空心球状金属,具有低密度、高强度的特性. Gama等(2001)对添加泡沫铝的陶瓷复合靶进行了数值模拟,研究了复合靶中应力波的传播.数值模拟结果表明泡沫铝的添加可以延迟应力波的传播与衰减.在陶瓷、泡沫铝、玻璃、橡胶组成的陶瓷复合靶中,陶瓷、泡沫铝、玻璃复合靶的性能最佳. Krishnan等(2010)采用JH-2陶瓷本构模型对子弹撞击陶瓷/UHMWPE(超高分子量聚乙烯)进行了建模与计算,数值模拟与实验结果相一致, 其数据对轻型装甲的设计具有指导作用.由于陶瓷复合靶结构的数值模拟不仅涉及多种材料参数,还需要考虑计算效率, 这类数值模拟还未进行系统的研究.

4.3 陶瓷界面击溃效应微观机制数值模拟

JH等唯象本构模型最大的缺点是许多描述非弹性过程的参数无法通过实验确定,需要另外加入非弹性机制描述材料的响应.这类本构模型对材料从完整到粉碎的过程的定义是主观的,与实验结果存在较大误差, 为材料参数的确定带来困难.基于陶瓷力学本质的本构模型则可以解决上述本构模型的不足.

陶瓷在撞击过程中的内部微裂纹变化是研究建立陶瓷力学本质的本构模型关键.Espinosa等( 1998a, 1998b)和 Zavattieri(2000),提出了基于固体微观力学的多平面微裂纹模型(MPM),在该模型中陶瓷的力学响应由晶粒大小、断裂韧性等材料微观结构参数决定.采用该本构模型的数值模拟可以反映射弹撞击陶瓷过程中的时间与空间响应,包括材料内部压力形成、剪切波的传播等,为了解界面击溃与侵彻现象提供良好的观测条件.Espinosa将该模型写入了EPIC95软件中用以研究陶瓷的非弹性行为.数值模拟结果表明陶瓷的界面击溃效应与弹靶结构、陶瓷种类、缓冲片及陶瓷的约束密切相关,尤其是盖板和背板的刚度决定了能否使陶瓷避免弯曲与拉伸波的破坏.此外,研究结果表明只有对弹靶进行同步的实验与数值模拟研究才能准确地进行轻型复合装甲的设计.Meyer等(2000)采用了统计裂纹力学(SCM)研究界面击溃效应,他将该陶瓷模型编入了波传播代码CTH进行裂纹扩展的模拟,数值模拟结果与实验结果吻合. Steinhauser和Grass(2005),采用了在JH模型基础上加入离散元模型(DEM),该模型可以重复实验中VISAR技术获得的实验数据以及实验中观测的断裂模式和应力应变行为.Deshpande和Evans(2008),~和 Deshpande等(2011),在有限元软件中采用DE陶瓷材料本构模型进行了陶瓷材料的动静态响应的数值模拟,通过观察陶瓷内部裂纹扩展等情况对本构模型的准确性进行了验证.该数值模拟方法可以获得不同应变率情况下的陶瓷内部非弹性变形行为,并分析拉伸波与压缩损伤对陶瓷破坏的影响.但由于陶瓷动态加载下数值模拟的复杂性,子弹及长杆弹撞击陶瓷的界面击溃与侵彻现象还未有公开报道.

5 总结与展望

现阶段研究表明界面击溃现象是一个多因素(陶瓷材料、约束条件、预应力、射弹材料、形状、交汇条件、盖板和背板的设计以及尺寸效应等)作用下的复杂动力学问题,与弹靶破坏的时间效应、靶中破坏波和陶瓷中裂纹与损伤的演化紧密相关.界面击溃的重要科学意义和广阔应用前景主要体现在:界面击溃过程中陶瓷材料的损伤演化及吸能机制、界面击溃形成机理与发展规律的深入研究将为丰富我国的终点毁伤和防护力学研究领域理论和技术突破奠定坚实基础,为我国弹道国防新材料的研究和制备提供科学依据,并促进我国新概念攻防武器和装备的研制. 在宏观尺度上,国内外学者在不同因素对陶瓷界面击溃效应的作用研究已取得了阶段性成果.在微观尺度上,国际上主要基于陶瓷内部裂纹扩展、损伤演化、塑性变形等机理分析界面击溃向侵彻转变的过程.国内学者对陶瓷界面击溃现象的研究起步较晚,关于陶瓷界面击溃综述性文献(陈小伟和陈裕泽 2006, 杨江丽和宋顺成 2007, Hu et al. 2009)对界面击溃的研究现状与发展进行了展望.理论方面的研究主要有李继承开展的界面击溃过程中弹靶参数变化(李继承和陈小伟 2011a, 2011b; Li et al. 2014, 2015; Li & Chen 2017)和高举斌等对背板对界面击溃的影响规律研究和陶瓷基复合材料弹靶表面驻留行为的分析(高举斌等 2013, 2017). 实验方面, 胡欣等(2010)通过对约束的AD95陶瓷进行弹击实验,获得了驻留现象. 未来可研究的方向主要有:

(1) 陶瓷本构模型.现阶段对陶瓷界面击溃效应的数值模拟工作主要采用JH-1或JH-2本构模型.JH模型是唯象学经验本构模型, 模型中参数测定复杂,在数值模拟过程中具有局限性. 发展完善陶瓷本构模型,才能减少参数校准实验, 提高数值模拟效率,建立可靠的长杆弹撞击装甲陶瓷界面击溃效应的数值模型.

(2) 陶瓷界面击溃效应的多尺度理论.现今的理论模型只能分析特定弹靶条件下的界面击溃现象, 适用性较窄,对界面击溃/侵彻转变速度的预测准确性有待提高.需要深入了解陶瓷靶冲击破坏过程的微观机制,研究界面击溃过程中陶瓷材料微裂纹扩展、损伤演化过程的特征参量,深入了解陶瓷材料冲击破坏微观机制与界面击溃间的关联机制,建立多因素耦合作用下陶瓷材料界面击溃/侵彻转变速度预测模型.

(3) 有限厚陶瓷复合装甲的界面击溃效应.现阶段的研究主要集中于半无限厚陶瓷靶界面击溃效应机制的解释,将半无限靶理论发展至有限厚陶瓷靶, 有助于轻型装甲的优化设计,对轻型装甲的工程应用具有指导意义.

(4) 陶瓷硬度对陶瓷界面击溃效应的影响.较高硬度的陶瓷可以使弹体在接触瞬间破碎,直接影响弹体对陶瓷的后续破坏.陶瓷硬度的提高可以显著提高界面击溃/侵彻转变速度.但硬度对界面击溃效应的作用机理并不明确,需要建立相应的模型进行描述.

(5) 新的弹道实验方法.现阶段关于长杆弹撞击装甲陶瓷界面击溃效应实验的研究均采用逆向弹道技术,需要耗费大量的人力物力, 实验的准确性也有待提高.设计新的实验发射装置以及采用相关替代实验以提高陶瓷界面击溃现象的研究效率是未来的研究发展趋势.

致谢

The authors have declared that no competing interests exist.


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Chinese Journal of Theoretical and Applied Mechanics, 43: 63-70).

DOI      URL      [本文引用: 6]      摘要

在Alekseevski-Tate模型基础上,理论分析了尖锥头长杆弹的界面击溃过程,分别给出在锥头侵蚀阶段和弹身侵蚀阶段的弹体速度下降及质量侵蚀计算公式;随后分析弹体的动能损失,讨论半锥角对弹体动能损失的影响.通过分析小子弹撞击陶瓷/金属复合靶板的例子,验证了该理论的正确性,并对比分析了尖锥头长杆弹与小子弹及平头长杆弹在界面击溃中动能损失之间的差异.
[6] 李继承, 陈小伟. 2011b.

柱形长杆弹侵彻的界面击溃分析

. 爆炸与冲击,31: 141-147

DOI      URL      [本文引用: 5]      摘要

在Alekseevski-Tate模型的基础上,分析了柱形长杆弹的界面击溃过程,给出了弹体速度下降及质量侵蚀的计算公式;讨论了弹体速度下降及质量侵蚀对动能损失的影响;特别针对柱形长杆弹在界面击溃过程中弹体速度准定常小量变化的特点,近似给出了弹体速度、弹体质量随时间变化的简化解析表达式,为工程应用提供便利。

(Li J C, Chen X W.2011b. Theoretical analysis on the interface defeat of a long rod penetration. Explosion and Shock Waves, 31: 141-147).

DOI      URL      [本文引用: 5]      摘要

在Alekseevski-Tate模型的基础上,分析了柱形长杆弹的界面击溃过程,给出了弹体速度下降及质量侵蚀的计算公式;讨论了弹体速度下降及质量侵蚀对动能损失的影响;特别针对柱形长杆弹在界面击溃过程中弹体速度准定常小量变化的特点,近似给出了弹体速度、弹体质量随时间变化的简化解析表达式,为工程应用提供便利。
[7] 满蓬. 2012.

氧化铝基陶瓷复合装甲面板与背板的配置效应研究

. [硕士论文]. 南京: 南京理工大学

URL      [本文引用: 1]      摘要

本文采用穿深试验方法对氧化铝基陶瓷复合装甲面板与背板的配置效 应(陶瓷厚度、面/背板界面状态、面/背板波阻抗匹配等主要因素)进行了研究。试验使用12.7mm穿甲燃烧弹垂直射击。陶瓷复合装甲由陶瓷面板和金属背 板组成。试验结果显示,在陶瓷面板厚度3.5mm~12mm范围内,随陶瓷面板厚度的增大,陶瓷面板的防护系数Nc先增加后降低,陶瓷复合装甲的防护系数 N先迅速增加而后增加趋势变缓,陶瓷面板存在(一)最佳厚度(约8mm),在此厚度时陶瓷面板的防护系数最大,即能最大程度的发挥陶瓷的高效抗弹性能。在 面板/背板配置不变的情况下,面/背板粘结时陶瓷复合装甲的...

(Man P.2012.

Study on the effect of configuration on front plate and back plate of ceramic composite armor based on Al$_{2}$O$_{3}$

. [Master Thesis]. Nanjing: Nanjing University of Science and Technology).

URL      [本文引用: 1]      摘要

本文采用穿深试验方法对氧化铝基陶瓷复合装甲面板与背板的配置效 应(陶瓷厚度、面/背板界面状态、面/背板波阻抗匹配等主要因素)进行了研究。试验使用12.7mm穿甲燃烧弹垂直射击。陶瓷复合装甲由陶瓷面板和金属背 板组成。试验结果显示,在陶瓷面板厚度3.5mm~12mm范围内,随陶瓷面板厚度的增大,陶瓷面板的防护系数Nc先增加后降低,陶瓷复合装甲的防护系数 N先迅速增加而后增加趋势变缓,陶瓷面板存在(一)最佳厚度(约8mm),在此厚度时陶瓷面板的防护系数最大,即能最大程度的发挥陶瓷的高效抗弹性能。在 面板/背板配置不变的情况下,面/背板粘结时陶瓷复合装甲的...
[8] 宋健. 2011.

弹体入射陶瓷复合靶板毁伤效应研究: [硕士论文]

. 哈尔滨: 哈尔滨工业大学

[本文引用: 1]     

(Song J.2011.

Research on damage effects of ceramic composite target under impact of projectile

. [Master Thesis]. Harbin: Harbin Institute of Technology).

[本文引用: 1]     

[9] 谈梦婷, 张先锋, 何勇, 刘闯, 于溪, 郭磊. 2016.

长杆弹撞击装甲陶瓷的界面击溃效应数值模拟

. 兵工学报, 37: 627-634

DOI      URL      [本文引用: 2]      摘要

利用动力有限元软件AUTODYN模拟了长杆弹撞击装甲陶瓷的界面击溃效应及其影响因素。在验证计算模型、参数及算法可靠的基础上,模拟研究了长杆弹头部形状、盖板、陶瓷预应力等对界面击溃效应的影响规律。结果表明:平头、球形和锥形头部形状长杆弹界面击溃/侵彻转变速度有显著差异;增加盖板及对陶瓷施加预应力均可减小陶瓷的损伤破坏程度,提高陶瓷的界面击溃/侵彻转变速度,提高装甲陶瓷抗弹能力。

(Tan M T, Zhang X F, He Y, Liu C, Yu X, Guo L.2016.

Numerical simulation on interface defeat of ceramic impacted by long-rod projectile

. Acta Armamentarii, 37: 627-634).

DOI      URL      [本文引用: 2]      摘要

利用动力有限元软件AUTODYN模拟了长杆弹撞击装甲陶瓷的界面击溃效应及其影响因素。在验证计算模型、参数及算法可靠的基础上,模拟研究了长杆弹头部形状、盖板、陶瓷预应力等对界面击溃效应的影响规律。结果表明:平头、球形和锥形头部形状长杆弹界面击溃/侵彻转变速度有显著差异;增加盖板及对陶瓷施加预应力均可减小陶瓷的损伤破坏程度,提高陶瓷的界面击溃/侵彻转变速度,提高装甲陶瓷抗弹能力。
[10] 谈梦婷, 张先锋, 葛贤坤, 刘闯, 熊玮. 2017.

长杆弹撞击装甲陶瓷界面击溃/侵彻转变速度理论模型

. 爆炸与冲击, 37: 1093-1100

DOI      URL      [本文引用: 1]      摘要

为预测长杆弹撞击装甲陶瓷界面击溃/侵彻转变过程,采用Hertz接触理论确定靶体内部应力,将其分别应用于陶瓷锥裂纹与翼型裂纹扩展理论。通过比较两种裂纹扩展模型计算得到的界面击溃/侵彻转变速度,提出准确预测界面击溃/侵彻转变速度的理论模型。结果表明:将两种裂纹扩展理论相结合的理论模型可以合理地解释界面击溃/侵彻转变过程,转变速度计算结果与已有实验结果吻合较好。弹体半径较小时,锥裂纹扩展控制界面击溃/侵彻转变过程;弹体半径较大时,翼型裂纹扩展控制界面击溃/侵彻转变过程。

(Tan M T, Zhang X F, Ge X K, Liu C, Xiong W.2017.

Theoretical model of interface defeat/penetration transition velocity of ceramic armor impacted by long-rod projectile

. Explosion and Shock Waves, 37: 1093-1100).

DOI      URL      [本文引用: 1]      摘要

为预测长杆弹撞击装甲陶瓷界面击溃/侵彻转变过程,采用Hertz接触理论确定靶体内部应力,将其分别应用于陶瓷锥裂纹与翼型裂纹扩展理论。通过比较两种裂纹扩展模型计算得到的界面击溃/侵彻转变速度,提出准确预测界面击溃/侵彻转变速度的理论模型。结果表明:将两种裂纹扩展理论相结合的理论模型可以合理地解释界面击溃/侵彻转变过程,转变速度计算结果与已有实验结果吻合较好。弹体半径较小时,锥裂纹扩展控制界面击溃/侵彻转变过程;弹体半径较大时,翼型裂纹扩展控制界面击溃/侵彻转变过程。
[11] 杨江丽, 宋顺成. 2007.

国外陶瓷材料抗侵彻研究进展

. 兵器材料科学与工程, 30: 72-74

DOI      URL      [本文引用: 1]      摘要

分别从理论分析及抗侵彻模型、陶瓷高应力率本构关系、数值计算与 数值模拟、陶瓷对侵彻弹丸的闭锁现象等方面给出国外陶瓷材料抗侵彻的研究进展.在理论分析模型中主要包括空穴膨胀理论、Tate方程的应用以及V50的计 算;在本构方程研究中Johnson-Holmquist模型和Partom模型令人关注;在数值计算方面,主要介绍用已有程序对人们感兴趣的问题进行的 研究.

(Yang J L, Song S C.2007.

Research progress in ceramic material for anti-penetration

. Ordnance Material Science and Engineering, 30: 72-74).

DOI      URL      [本文引用: 1]      摘要

分别从理论分析及抗侵彻模型、陶瓷高应力率本构关系、数值计算与 数值模拟、陶瓷对侵彻弹丸的闭锁现象等方面给出国外陶瓷材料抗侵彻的研究进展.在理论分析模型中主要包括空穴膨胀理论、Tate方程的应用以及V50的计 算;在本构方程研究中Johnson-Holmquist模型和Partom模型令人关注;在数值计算方面,主要介绍用已有程序对人们感兴趣的问题进行的 研究.
[12] Alekseevski V P.1966.

Penetration of a rod into target at high velocity

. Combustion, Explosion, and Shock Waves, 2: 63-66.

DOI      URL      [本文引用: 1]      摘要

No Abstract available for this article.
[13] Anderson Jr C E.2006.

A review of computational ceramic armor modeling. Ceramic Engineering and Science Proceedings

, American Ceramics Society. 27: 1-18

[本文引用: 2]     

[14] Anderson Jr C E.2009.

Dwell and postdwell penetration of long rods on borosilicate glass targets

. Shock Compression of Condensed Matter, 1195: 1447-1452.

[本文引用: 5]     

[15] Anderson Jr C E.2010.

Dwell and interface defeat on borosilicate glass

. International Journal of Applied Ceramic Technology, 7: 776-786.

DOI      URL      [本文引用: 4]      摘要

We have conducted impact experiments using gold long rods into borosilicate glass and the measured the penetration velocity as a function of impact velocity. At sufficiently low-impact velocities, the glass target resists penetration and there is dwell; dwell is observed to approximately 450 m/s for bare glass. If a copper buffer is placed over the glass to eliminate the impact shock, significant dwell can be seen at impact velocities as high as 890 m/s. These impact velocities correspond to Bernoulli stresses of approximately 2.0 and 7.6 GPa, respectively. The paper describes the experimental data, and summarizes the results and our findings.
[16] Anderson Jr C E, Gooch W A.2011.

Numerical simulations of dynamic X-ray imaging experiments of 7.62-mm Apm2 projectiles penetrating B4C//19th International Symposium of Ballistics,

Interlaken, Switzerland. 1423-1429.

[本文引用: 2]     

[17] Anderson Jr C E, Morris B L.1992.

Ballistic performance of confined alumina ceramic tiles

. International Journal of Impact Engineering, 12: 167-187.

DOI      URL      [本文引用: 2]      摘要

The penetration of aluminum oxide tiles inserted into a 4340-steel block that also serves as a emi-infinite steel substrate is investigated for two length-to-diameter projectiles at a nominal impact velocity of 1.5 km/s. The experimental observable is the depth of penetration of the projectile into the backup steel. These data are compared with the total penetration into semi-infinite steel. The data are analysed and displayed as normalized depth of penetration as a function of areal density and tile thickness. Data from Woolsey et al. ( Fifth Annual TACOM Armor Coordinating Conference , Monterey, CA, 1989) are in good agreement with data from this study, and are used to extend the range of tile thicknesses. A methodology, assuming quasi-steady-state penetration, provides an estimate of the penetration resistance R 1 of the ceramic tile; R 1 is then used to estimate the erosion rate and length of projectile eroded as it penetrates the ceramic. A second approach that does not rely as heavily on the assumption of steady-state penetration is also developed and applied to the data to estimate the length of projectile eroded. It is found that the various measures of ceramic performance, for a well-confined target, are relatively constant as tile thickness is varied.
[18] Anderson Jr C E, Orphal D L.2003.

Analysis of the terminal phase of penetration

. International Journal of Impact Engineering, 29: 69-80.

DOI      URL      [本文引用: 1]      摘要

ABSTRACT The terminal phase, or Phase 3, of penetration is investigated using numerical simulations. Results of the first set of simulations, for zero-strength tungsten-alloy projectiles into armor steel at velocity of 1.5, 3.0, and 6.0 km/s are reported here. For these simulations, the mechanisms for Phase 3 penetration are limited to the transient deceleration of the eroding projectile and "afterflow," the extension of penetration after the projectile has fully eroded. It is found that for projectile L/D less than or equal to similar to2, there is effectively no steady-state penetration (Phase 2) and penetration is dominated by Phase 3. For projectiles of L/D greater than or equal to 3, steady-state penetration is achieved. For L/D greater than or equal to 3, the deceleration of both the nose and tail of the projectile are essentially independent of LID. For LID greater than or equal to 3, the target penetration associated with Phase 3 is found to increase with impact velocity approximately as P-3/D proportional to V (1.0). "After-flow" as a separate, identifiable mechanism could not be discerned in the results. We therefore question whether the phenomenon of "after-flow," as usually defined, exists; rather, projectile deceleration and crater depth growth are intimately coupled.
[19] Anderson Jr C E, Royal-Timmons S A.1997.

Ballistic performance of confined 99.5%-Al$_{2}$O$_{3}$ ceramic tiles

. International Journal of Impact Engineering, 19: 703-713.

DOI      URL      [本文引用: 3]     

[20] Anderson Jr C E, Walker J D.1991.

An examination of long-rod penetration

. International Journal of Impact Engineering, 11: 481-501.

DOI      URL      [本文引用: 2]      摘要

The one-dimensional modified Bernoulli theory of Tate [ J. Mech. Phys. Solids 15 , 287 399 (1967)] is often used to examine long-rod penetration into semi-infinite targets. The theory is summarized and the origins of the target resistance term examined. Numerical simulations were performed of a tungsten-alloy, long-rod projectile into a semi-infinite hardened steel target at three impact velocities sufficiently high to result in projectile erosion. The constitutive responses of the target and projectile were varied parametrically to assess the effects of strain hardening, strain-rate hardening, and thermal softening on penetration response. The results of one of the numerical simulations were selected to compare and contrast in detail with the predictions of the Tate model.
[21] Anderson Jr C E, Walker J D.2005.

An analytical model for dwell and interface defeat

. International Journal of Impact Engineering, 31: 1119-1132.

DOI      URL      [本文引用: 6]      摘要

An analytical model that captures the essential mechanics of dwell and interface defeat—the phenomenon where an impacting projectile flows radially outward (erodes) along the surface of the target (usually ceramic) with no significant penetration—is presented. During dwell, the projectile loses kinetic energy due to mass loss and deceleration. It is shown that model predictions are in very good agreement with experimental data.
[22] Anderson Jr C E, Behner T, Templeton D W, Holmquist T J, Wickert M, Hohler V.2006.

Interface defeat of long rods impacting borosilicate glass

. Southwest Research Inst San Antonio Tx.

[本文引用: 1]     

[23] Anderson Jr C E, Behner T, Orphal D L, Nicholls A E, Templeton D W.2008.

Time-resolved penetration into pre-damaged hot-pressed silicon carbide

. International Journal of Impact Engineering, 35: 661-673.

DOI      URL      [本文引用: 2]      摘要

We have conducted a series of experiments to examine projectile penetration of cylindrical hot-pressed silicon carbide (SiC) ceramic targets that are pre-damaged to varying degrees under controlled laboratory conditions prior to ballistic testing. SiC was thermally shocked to introduce non-contiguous cracks. Another set of targets was thermally shocked and then additional damage was induced by load nload cycling in an MTS machine while the ceramic specimen was confined in a 7075-T6 aluminum sleeve. Finally, targets were made by compacting SiC powder into a 7075-T6 aluminum sleeve. For each of these target types, long gold rod penetration was measured as a function of impact velocity v p over the approximate range of 1 3 km/s, with most data between 1.5 and 3 km/s. Penetration as a function of time was measured using multiple independently timed flash X-rays. Results are compared with previous results for non-damaged (intact) SiC targets. Key results from these experiments include the following: (1) penetration is nominally steady state for v p>1.5 km/s; (2) for all target types, the penetration velocity u is a linear function of v p (except for the lowest impact velocities); and (3) it is found that u intact< u pre-damaged< u in-situ comminuted< u powder< u hydrodynamic.
[24] Anderson Jr C E, Behner T, Holmquist T J, Orphal D L, Wickert M.2009.

Dwell, interface defeat, and penetration of long rods impacting silicon carbide

. Southwest Research Institute Technical Report.

URL      [本文引用: 3]     

[25] Anderson Jr C E, Behner T, Holmquist T J, King N L, Orphal D L.2011a.

Interface defeat of long rods impacting oblique silicon carbide

//Proceedings of 26th International Symposium on Ballistics, Miami, FL, USA, DEStech Publications, Inc, Lancaster, PA, USA (1728-1735).

[本文引用: 6]     

[26] Anderson Jr C E, Behner T, Holmquist T J, Orphal D L.2011b.

Penetration response of silicon carbide as a function of impact velocity

. International Journal of Impact Engineering, 38: 892-829.

DOI      URL      [本文引用: 1]      摘要

Reverse ballistic experiments were used to investigate confinement, pre-damaged and intact, and rod size effects on penetration of long, gold rods into silicon carbide (SiC-N). Rod diameters were 1.002mm and 0.7502mm, and lengths were 7002mm and 5002mm, respectively. Within data scatter, penetration velocity was the same for intact (bare or sleeved), pre-damaged (thermally shocked with non-contiguous cracks), and Highlights? Penetration rate of long Au rods into SiC determined as function of impact velocity. ? Intact, pre-damaged, in situ comminuted, sleeved, and bare SiC tested. ? Two different rod diameters tested. ? Penetration function of impact velocity but independent of other variables examined. ? Failure front predamages ceramic in front of rod, so rod penetrates failed material.
[27] Anderson Jr C E, Burkins M S, Walker J D, Gooch W A.2005.

Time-resolved penetration of B4C tiles by the APM2 bullet

. CMES, 8: 91-104.

[28] Anderson Jr C E, Littlefield D L, Walker J D.1993a.

Long-rod penetration, target resistance, and hypervelocity impact

. International Journal of Impact Engineering, 14: 1-12.

DOI      URL      [本文引用: 2]     

[29] Anderson Jr C E, Mullin S A, Kuhlman C J.1993b.

Computer simulation of strain-rate effects in replica scale model penetration experiments

. International Journal of Impact Engineering, 13: 35-52.

DOI      URL      摘要

A computational study was performed to quantify the effects of strain rate on replica-model (scaled) experiments of penetration and perforation. The impact of a tungsten-alloy, long-rod projectile into an armor steel target at 1.5 km s 1 was investigated. It was found that over a scale factor of 10, strain-rate effects change the depth of penetration, for semi-infinite targets, and the residual velocity and length of the projectile, for finite-thickness targets, by an order of 5%. Although not modeled explicitly in the present study, the time-dependence of damage was examined. Damage accumulation is a strong function of absolute time, not scaled time. At homologous times, a smaller scale will have less accumulated damage than a larger scale; therefore, the smaller scale will appear stronger, particularly in situations where the details of damage evolution are important.
[30] Anderson Jr C E, Orphal D L, Franzen R R, Walker J D.1999.

On the hydrodynamic approximation for long-rod penetration

. International Journal of Impact Engineering, 22: 23-43.

DOI      URL      摘要

Steady-state hydrodynamic theory, or variations thereof, has been applied to long-rod penetration since the 1940s. It is generally believed that projectile strength is of little consequence at high velocities, and that hydrodynamic theory is applicable to long-rod penetration when penetration pressures are much greater than the target flow stress. Substantiating this belief is the observation that at approximately 2.5 km/s, for tungsten alloy projectiles into armor steel, normalized penetration (P/L) nominally saturates to the classical hydrodynamic limit of the square root of the ratio of the projectile to target densities. Experimental data herein, however, show penetration velocities and instantaneous penetration efficiencies fall below that expected from hydrodynamic theory, even at impact velocities as high as 4.0 km/s. Numerical simulations, using appropriate strength values, are in excellent agreement with the experimental data. Parametric studies demonstrate that both projectile and target strength have a measurable effect even at such high impact velocities.
[31] Anderson Jr C E, Walker J D, Lankford J.1995.

Investigation of the ballistic response of brittle materials

. Southwest Research Inst San Antonio Tx.

[本文引用: 2]     

[32] Andersson O, Lundberg P, Renström R.2007.

Influence of confinement on the transition velocity of silicon carbide//Proceedings of 23rd International Symposium on Ballistics, Tarragona,

Spain, April. 16-20.

[本文引用: 4]     

[33] Ashby M F, Hallam S D.1986.

The failure of brittle solids containing small cracks under compressive stress rates

. Acta Metall, 34: 497-510.

DOI      URL      [本文引用: 1]      摘要

Brittle materials (ceramics, rocks and ice are examples) may contain a distribution of small, grain-sized, cracks. When loaded in compression, these cracks propagate stably until they interact to give final failure. A model is developed for the growth and interaction of cracks in brittle solids under compressive stress states. A critical stress is required to initiate crack growth: it depends on the initial crack length and orientation, on the coefficient of friction and on the stress state. The cracks then grow in a stable way until they start to interact; interaction increases the stress intensity driving crack growth and leads to instability and final failure. This chain of events is modelled, and the framework of a theory of damage mechanics is suggested.
[34] Ashby M F, Sammis C G.1990.

The damage mechanics of brittle solids in compression

. Pure & Applied Geophysics, 133: 489-521.

DOI      URL      [本文引用: 1]      摘要

The development of microcrack damage in brittle solids in compression is analyzed, using a simple model. The model is developed from recent detailed analysis of the initiation, propagation and linkage of microfractures from pre-existing cracks, voids, or other inhomogeneities. It describes the evolution of damage with strain and from it a criteria for failure can be established. The results are used to construct failure surfaces in stress space which combine information about brittle failure with data describing the onset of plastic yielding. Such failure surfaces are constructed for a number of rocks and are compared with previously published experimental data.
[35] Aydelotte B, Schuster B.2015.

Impact and penetration of SiC: The role of rod strength in the transition from dwell to penetration

. Procedia Engineering, 103: 19-26.

DOI      URL      [本文引用: 1]      摘要

The phenomenon of dwell during projectile impact on ceramics has been an active area of research for several decades. Dwell in confined ceramics has received much attention, particularly the role of cover plates and their influence over the dwell to penetration transition. Dwell during long rod impact on unconfined ceramics has received relatively less attention. The present work will compare and contrast the results of two series of long rod impacts on hot pressed silicon carbide targets. One series utilized gold wire rods. The other series utilized rods fabricated from tungsten carbide with 10% cobalt matrix. A novel ten-flash X-ray system captured spatially resolved images of the penetration events. The experimental results are compared with simulations and predictions from the Alekseevskii-Tate equation to explore the role of shock pressure, the effects of the strength of the rod material in dwell to penetration transition behavior, and the behavior of defects within silicon carbide.
[36] Behner T, Anderson Jr C E, Holmquist T J, et al.2008.

Interface defeat for unconfined SiC ceramics. Army Tank-Automotive and

Armaments Command Warren Mi.

[本文引用: 2]     

[37] Behner T, Anderson Jr C E, Holmquist T J, Orphal D L, Wickert M, Templetone D W.2011.

Penetration dynamics and interface defeat capability of silicon carbide against long rod impact

. International Journal of Impact Engineering, 38: 419-425.

DOI      URL      [本文引用: 2]      摘要

To determine the behavior of silicon carbide (SiC) against long rod impact a detailed study with experiments in the velocity range from 0.8 to 3 km/s at normal impact conditions was performed in recent years. Interest ranged from penetration performance of intact and pre-damaged SiC to interface defeat capability of SiC. Together with impact data in the hypervelocity regime this paper provides a comprehensive overview of the penetration dynamics of SiC over a wide velocity range and during different phases of the penetration process.
[38] Behner T, Heine A, Wickert M.2013.

Protective properties of finite-extension ceramic targets against steel and copper projectiles//27th International Symposium on Ballistics,

Freiburg, Germany. 1598-1607.

[本文引用: 1]     

[39] Behner T, Heine A, Wickert M.2016.

Dwell and penetration of tungsten heavy alloy long-rod penetrators impacting unconfined finite-thickness silicon carbide ceramic targets

. International Journal of Impact Engineering, 95: 54-60.

DOI      URL      [本文引用: 3]      摘要

Impact experiments with a tungsten heavy alloy long rod projectile against silicon carbide tiles were performed to study the transition from dwell to penetration and to compare against earlier investigations which focused either on small scale semi-infinite set-ups or on finite thickness set-ups with confinement. A depth-of-penetration configuration consisting of a ceramic tile and an extended steel backing was used to assess the impact response of the unconfined finite-thickness ceramic. The ceramic tile was either bare or had a cover plate attached to the front. The cover plate thickness has been varied and gives best results for a thickness of about half the projectile diameter used in the experiments. For the bare ceramic, a long dwell phase can be maintained up to impact velocities of around 900 /s. For the buffered ceramic, partial dwell can be achieved up to around 1700 /s. The results corroborate those of earlier investigations mentioned above. More importantly, the present results show that it is possible to substantially erode a heavy alloy long-rod penetrator at the surface of a finite thickness ceramic element without lateral confinement in direct impact experiments even at high impact velocities.
[40] Bless S, Benyami M, Apgar L.1992.

Structures under shock and impact II

. Computational Mechanics.

URL      [本文引用: 1]      摘要

This Work Brings Together The Experience Of Specialists In The Behaviour Of Concrete And Metal Structures, Both Above And Below The Ground, To Actions Of Blast, Penetration And High Speed Collisions. From The Second International Conference, "structures Under Shock And Impact", This Volume Aims To Help Stimulate Future Research Analysis.
[41] Bourne N.2010.

On kinetics of failure in, and resistance to penetration of metals and ceramics

. Advances in Applied Ceramics, 109: 480-486.

DOI      URL      [本文引用: 1]      摘要

The performance of armour materials depends upon the deformation mechanisms operating during the penetration process. The critical mechanisms determining the behaviour of armour ceramics have not been isolated using traditional ballistics. It has recently become possible to measure strength histories in materials under shock. The data gained for the failed strength of the armour are shown to relate directly to the penetration measured. Furthermore, it has been demonstrated in one-dimensional strain that the material can be loaded and recovered for post-mortem examination. Failure is by microfracture, which is a function of the defects and then cracking activated by plasticity mechanisms within the grains and failure at grain boundaries in the amorphous intergranular phase. Thus, it appears that the shock induced plastic yielding of grains at the impact face that determines the later time penetration through the tile.
[42] Chen W.1995.

Dynamic failure behavior of ceramics under multiaxial compression

. California Institute of Technology//Joint Applied Mechanics and Materials Summer Meeting, Los Angeles, CA.

URL      [本文引用: 1]      摘要

An experimental technique has been developed that is capable of (1) dynamically loading the specimen in multiaxial compression; (2) controlling the stress state in the specimen in the range from uniaxial stress to uniaxial strain; and (3) allowing the recovery of the sample after loaded by a single, well defined pulse for the characterization of the failure mode. In this technique, cylindrical ceramic specimens were loaded in the axial direction using a split Hopkinson pressure bar modified to apply a single loading pulse, and were confined laterally either by shrink fit sleeves, or by eletro-magnetic force. Quasi-static and dynamic multiaxial compression experiments have been performed on a machinable glass ceramic, Macor, and a monolithic engineering ceramic, sintered aluminum nitride (A1N). The cylindrical ceramic specimens were confned laterally by shrink fit sleeves: the amount of confining pressure (0-230 MPa) was varied by using different sleeve materials. The quasi-static axial load was applied by a hydraulic driven Material Test System (MTS), whereas the dynamic axial load was provided by a modified split Hopkinson (Kolsky) pressure bar (SHPB). Under both quasi-static and dynamic loading conditions, the experimental results for both materials showed that the failure mode changed from fragmentation by axial splitting under conditions of uniaxial stress (without lateral confinement) to localized deformation on faults under moderate lateral confinement. The fault initiation process was studied experimentally in detail. Based on the experimental results, a compressive brittle failure process was summarized. A transition from brittle to ductile behavior was observed in Macor under high confinement pressure which was achieved using a second sleeve around the inner sleeve. The compressive failure strengths of both materials increased with increasing confinement pressure under both quasi-static and dynamic loading conditions. The highest dynamic compressive strengths of Macor and A1N measured in the experiments were 1.35 GPa and 5.40 GPa, respectively, whereas their quasi-static compressive strength were measured to be 0.43 GPa and 2.5 GPa, respectively. Based on the experimental results on A1N together with available data in the literature, a failure/flow criterion was developed for ceramic materials under multiaxial loading. A Mohr-Coulomb criterion and an improved Johnson-Holmquist model were found to fit the experimental data for brittle failure, whereas the materials exhibited pressure insensitive plastic flow at high pressures. Observations made in other types of dynamic experiments (e.g., shock wave loading) were rationalized based on the postulated failure mechanisms and the possibility of plastic flow beyond the Hugoniot elastic limit (HEL). The effect of various material properties on the failure behavior was investigated using the proposed failure criterion. The applicability of the present model to a range of ceramics was also explored and the limitations of the model were outlined.
[43] Chi R, Serjouei A, Sridhar I, Tan G E B.2013.

Ballistic impact on bi-layer alumina/aluminium armor: A semi-analytical approach

. International Journal of Impact Engineering, 52: 37-46.

DOI      URL      [本文引用: 3]      摘要

This paper presents a semi-analytical approach on the performance of ceramic/metal armor under ballistic impact. Numerical simulations for alumina/aluminum armor impacted by 20 mm APDS in AUTODYN were carried out and verified against the experimental data. Comprehensive numerical simulations were performed using the verified numerical model material parameters providing corroborative data for ensuing discussions. A semi-analytical model relating projectile residual velocity, impact velocity and armor ballistic limit velocity (BLV) is presented for impact of hard projectile against ceramic/metal armor. It is shown that the projectile residual velocity and BLV satisfy the replica scaling laws. Based on the replica scaling laws of projectile residual velocity and BLV, an empirical equation for BLV is obtained and used for armor optimization applications giving reasonable results similar to experiments available in the literature. [All rights reserved Elsevier].
[44] Chi R, Serjouei A, Sridhar I, Geoffrey T E B.2015.

Pre-stress effect on confined ceramic armor ballistic performance

. International Journal of Impact Engineering, 84: 159e70.

DOI      URL      [本文引用: 2]      摘要

61Numerical modeling of pre-stressed confined SiC is performed and validated against the experimental measurements.61Effect of different pre-stress types on ballistic behavior of armor is explored.61Effect of “pressure at initial failure point” on ballistic behavior of SiC is studied.61Dwell–penetration transition velocity for different pre-stressed SiC targets is found.
[45] Crouch I G, Appleby-Thomas G, Hazell P J.2015.

A study of the penetration behavior of mild-steel-cored ammunition against boron carbide ceramics armours

. International Journal of Impact Engineering, 80: 203-211.

DOI      URL      [本文引用: 1]      摘要

61Stripping the jacket and filler material from AK47 MSC rounds appears to make a difference to its penetrating ability when impacting a boron carbide ceramic target.61The magnitude of this effect is much greater than previously reported for high-strength steel-cored rounds and for tungsten carbide-cored rounds.61The penetration event appears to be a two-stage process: mushrooming of the mild steel core on, or near, the surface of the ceramic, followed by a linear erosion process.61The second step has not been reported previously for MSC rounds.
[46] Dehn J.1996.

Modeling armor that uses interface defeat

. AIP Conference Proceedings, 370: 1139-1142.

DOI      URL      [本文引用: 1]      摘要

It is possible to erode completely certain projectiles at the face of a ceramic block, provided the ceramic is confined suitably and is considerably stronger than the projectile. Lower projectile speeds, densities and length-to-diameter ratios favor this phenomenon. Heavy ceramic confinement and the use of shock attenuators also favor projectile interface defeat. In this paper we report on our use of the wave code HULL to study some of the factors which govern this phenomenon.
[47] Den Reijer PC.1991.

Impact on ceramic faced armour: TU Delft

. Dutch: Delft University of Technology.

[本文引用: 1]     

[48] Deshpande V S, Evans A G.2008.

Inelastic deformation and energy dissipation in ceramics: A mechanism-based constitutive model

. Journal of the Mechanics and Physics of Solids, 56: 3077-3100.

DOI      URL      [本文引用: 3]      摘要

A mechanism-based constitutive model is presented for the inelastic deformation and fracture of ceramics. The model comprises four essential features: (i) micro-crack extension rates based on stress-intensity calculations and a crack growth law, (ii) the effect of the crack density on the stiffness, inclusive of crack closure, (iii) plasticity at high confining pressures, and (iv) initial flaws that scale with the grain size. Predictions of stress/strain responses for a range of stress states demonstrate that the model captures the transition from deformation by micro-cracking at low triaxiality to plastic slip at high triaxialities. Moreover, natural outcomes of the model include dilation (or bulking) upon micro-cracking, as well as the increase in the shear strength of the damaged ceramic with increasing triaxiality. Cavity expansion calculations are used to extract some key physics relevant to penetration. Three domains have been identified: (i) quasi-static, where the ceramic fails due to the outward propagation of a compression damage front, (ii) intermediate velocity, where an outward propagating compression damage front is accompanied by an inward propagating tensile (or spallation) front caused by the reflection of the elastic wave from the outer surface and (iii) high velocity, wherein plastic deformation initiates at the inner surface of the shell followed by spalling within a tensile damage front when the elastic wave reflects from the outer surface. Consistent with experimental observations, the cavity pressure is sensitive to the grain size under quasi-static conditions but relatively insensitive under dynamic loadings.
[49] Deshpande V S, Gamble E, Compton B G, McMeeking R M, Evans A G, Zok F W.2011.

A constitutive description of the inelastic response of ceramics

. Journal of the American Ceramic Society, 94: S204-S214.

DOI      URL      [本文引用: 3]      摘要

The objective of the article is to present a unified model for the dynamic mechanical response of ceramics under compressive stress states. The model incorporates three principal deformation mechanisms: (i) lattice plasticity due to dislocation glide or twinning; (ii) microcrack extension; and (iii) granular flow of densely packed comminuted particles. In addition to analytical descriptions of each mechanism, prescriptions are provided for their implementation into a finite element code as well as schemes for mechanism transitions. The utility of the code in addressing issues pertaining to deep penetration is demonstrated through a series of calculations of dynamic cavity expansion in an infinite medium. The results reveal two limiting behavioral regimes, dictated largely by the ratio of the cavity pressure p to the material yield strength Y. At low values of p/ Y, cavity expansion occurs by lattice plasticity and hence its rate diminishes with increasing Y. In contrast, at high values, expansion occurs by microcracking followed by granular plasticity and is therefore independent of Y. In the intermediate regime, the cavity expansion rate is governed by the interplay between microcracking and lattice plasticity. That is, when lattice plasticity is activated ahead of the expanding cavity, the stress triaxiality decreases (toward more negative values) which, in turn, reduces the propensity for microcracking and the rate of granular flow. The implications for penetration resistance to high-velocity projectiles are discussed. Finally, the constitutive model is used to simulate the quasi-static and dynamic indentation response of a typical engineering ceramic (alumina) and the results compared to experimental measurements. Some of the pertinent observations are shown to be captured by the present model whereas others require alternative approaches (such as those based on fracture mechanics) for complete characterization.
[50] Espinosa H D, Zavattieri P D, Dwivedi S K.1998a.

A finite deformation continuum/discrete model for the description of fragmentation and damage in brittle materials

. Journal of the Mechanics and Physics of Solids, 46: 1909-1942.

DOI      URL      摘要

A dynamic finite element analysis of large displacements, high strain rate deformation behavior of brittle materials is presented in total Lagrangian coordinates. A continuum discrete damage model capable of capturing fragmentation at two size scales is derived by combining a continuum damage model and a discrete damage model for brittle failure, It is assumed that size and distribution of potential fragments are known a priori, through either experimental findings or materials properties, and that macrocracks can nucleate and propagate along the boundaries of these potential fragments. The finite deformation continuum multiple-plane microcracking damage model accounts for microcracks within fragments. Interface elements, with cohesive strength and reversible unloading before debonding, between potential fragments describe the initiation of macrocracks, their propagation, and coalescence leading to the formation of discrete fragments. A surface-defined multibody contact algorithm with velocity dependent friction is used to describe the interaction between fragments and large relative sliding between them. The finite element equations of motion are integrated explicitly using a variable time step. Outputs are taken at discrete time intervals to study material failure in detail. The continuum discrete damage model and the discrete fragmentation model, employing interface elements alone, are used to simulate a ceramic rod on rod impact. Stress wave attenuation, fragmentation pattern, and overall failure behavior, obtained from the analyses using the two models, are compared with the experimental result and photographs of the failing rod. The results show that the continuum discrete model captures the stress attenuation and rod pulverization in agreement with the experimental observations while the pure discrete model underpredicts stress attenuation when the same potential fragment size is utilized. Further analyses are carried out to study the effect of potential fragment size and friction between sliding fragments It is found that compared with the continuun discrete damage model, the discrete fragmentation model is more sensitive to the multi-body discretization.
[51] Espinosa H D, Dwivedi S, Zavattieri P, Yuan G.1998b.

A numerical investigation of penetration in multilayered material/structure systems

. International Journal of Solids and Structures, 35: 2975-3001.

DOI      URL      [本文引用: 1]      摘要

ABSTRACT The response of multilayered ceramic/steel targets to high velocity impact and penetration has been investigated through finite element simulations. A multiple-plane microcracking model has been used to describe the inelastic constitutive behavior of ceramics in the presence of damage. The model has been integrated into the finite element code EPIC95, which possesses contact and erosion capabilities particularly suitable for ballistic simulations. The integrated code has been used to analyze the depth of penetration (DOP) and interface defeat (ID) ceramic target configurations. Parametric analyses have been carried out to establish the effect of ceramic materials, target configuration design for ceramic confinement, diameter/length (d/L) ratio of the penetrator, material erosion threshold levels and the use of a shock attenuator on the response of multilayered targets subjected to high velocity impact. The response characteristics are established in terms of the parameters which can be measured experimentally. The analyses show that the integrated code is able to predict the response of ceramic targets in confirmation with experimental findings reported in the literature. The penetration process is found to be less dependent on the ceramic materials as usually assumed by most investigators. By contrast, the penetration process is highly dependent on the multilayered configuration and the target structural design (geometry, and boundary conditions). From a simulation standpoint, it has been found that the erosion parameter plays an important role in predicting the deformation history and interaction of the penetrator with the target. These findings show that meaningful lightweight armor design can only be accomplished through a combined experimental/numerical study in which relevant ballistic materials and structures are simultaneously investigated.
[52] Feli S, Asgari M.2011.

Finite element simulation of ceramic/composite armor under ballistic impact

. Composites Part B: Engineering, 42: 771-780.

DOI      URL      [本文引用: 1]      摘要

In this paper, based on LS-Dyna code, a new finite element (FE) simulation of the ballistic perforation of the ceramic/composite targets, which impacted by cylindrical tungsten projectiles, has been presented. Research on this method has been conducted by a few research groups in recent years. The ceramic material, which is the front plate, has been made of Alumina 99.5% and composite back-up plate composed of Twaron fibers. The 2-dimensional (2D), axi-symmetric, dynamic-explicit, Lagrangian model has been considered in this simulation. The Johnson-Cook, Johnson-Holmquist and Composite-Damage materials behaviors have been used for projectile, ceramic and composite materials respectively. The brittle fracture and fragmentation of ceramic conoid, the failure criteria based on fracture of fibers or matrixes of composite materials and erosion or flattening of projectile during perforation have been considered. The residual velocity and perforation time has been obtained and compared with the available analytical models. The results show that when the ceramic is impacted by a projectile, a fragmented ceramic conoid breaks from ceramic tile and the semi-angle of ceramic conoid with increasing initial velocity decreases. Furthermore, the dishing of composite layers at high impact velocities and the delamination of layers near the ballistic limit velocity decrease. [All rights reserved Elsevier].
[53] Fischer-Cripps A C.2010.

Introduction to Contact Mechanics

. Springer Berlin.

[本文引用: 4]     

[54] Flinders M, Ray D, Anderson A, Cutler R A.2005.

High-toughness silicon carbide as armor

. Journal of the American Ceramic Society, 88: 2217-2226.

DOI      URL      [本文引用: 1]      摘要

Silicon carbide, with single-edge precracked beam (SEPB) toughness greater than 7 MPa·m 1/2 , was made by hot-pressing using Al–B–C (ABC) or Al–Y 2 O 3 (YAG) as additives. The hardness of SiC processed with a liquid phase was always less than SiC densified without a liquid phase despite having a similar or finer grain size. With increasing Al content, the ABC system changed from trans- to intergranular fracture with a drop in hardness and a two- to threefold increase in SEPB toughness. Strength and Weibull modulus for materials processed with a liquid phase were higher than those of solid-state densified SiC. Ballistic testing, however, did not show any improvement over SiC densified with B and C additives. Depth of penetration was controlled by hardness of the SiC-based materials, while V 50 values for 14.5 mm WC–Co cored projectiles were in the range of 720–750 m/s for all materials tested.
[55] Fountzoulas C, Cheeseman B, LaSalvia J.2009.

Simulation of ballistic impact of a tungsten carbide sphere on a confined silicon carbide target//Proceedings of the 23rd International Symosium on Balllistics, Tarragona, Spain

.

[本文引用: 2]     

[56] Fountzoulas C, LaSalvia J.2011.

Simulation of the ballistic impact of tungsten-based penetrators on confined hot-pressed boron carbide targets

. Advances in Ceramic Armor VII: Ceramic Engineering and Science Proceedings, 32: 261-269.

DOI      URL      [本文引用: 1]      摘要

Summary This chapter contains sections titled: Introduction Experimental Details Numerical Simulations Discussion Conclusions
[57] Fountzoulas C, LaSalvia J.2012.

Improved modeling and simulation of the ballistic impact of tungsten-based penetrators on confined hot-pressed boron carbide targets

. Adv Ceram Armor VIII, John Wiley & Sons, Inc. 209-217.

DOI      URL      [本文引用: 1]      摘要

Summary This chapter contains sections titled: Introduction Experimental Details Numerical Simulations Discussion Conclusions
[58] Fountzoulas C G, LaSalvia J C.2013.

Material models sensitivity of tungsten-based penetrators impacting on confined boron-carbide

. Dynamic Behavior of Materials, 1: 251-258.

DOI      URL      [本文引用: 1]      摘要

LaSalvia et al. (LaSalvia presentation (2010) Ballistic impact damage in hot- pressed boron carbide 34 ICACC, Daytona Beach, 25 29 Jan 2010) studied experimentally the interaction of confined hot-pressed boron carbide (B 4 C) targets impacted by laboratory-scale tungsten-based long-rod penetrators. To better understand the physics involved, Fountzoulas et al. (Fountzoulas CG, LaSalvia JC (2011) Simulation of the ballistic impact of tungsten-based penetrators on confined hot-pressed boron carbide targets. In: Proceedings of 35th ICACC, Advances in Ceramic Armor VII, p 261) studied by modeling and simulation the ballistic behavior of these targets. To satisfactorily replicate the experimental damage of the targets during impact, the material strength and failure models were iteratively modified. Despite numerous iterations, the damage replication of the target was only partially successful. The fracture of B 4 C was able to be replicated to some extent but without being able to stop its penetration by the projectile, a disagreement with the experimental observations. The current effort reports on the sensitivity and modification of the existing strength and failure B 4 C material models of the ANSYS/AUTODYN library to predict the tensile failure to accurately simulate the ballistic response of ceramics.
[59] Franzen R, Orphal D, Anderson C.1997.

The influence of experimental design on depth-of-penetration (DOP) test results and derived ballistic efficiencies

. International Journal of Impact Engineering, 19: 727-737.

DOI      URL      [本文引用: 1]      摘要

Abstract Experimental data for ceramic armor materials from two test methods, small-scale reverse ballistic tests and depth-of-penetration (DOP) tests, are reviewed and compared. Results from reverse ballistic tests can be used to estimate the length of rod erosion in the ceramic tiles of DOP tests. The outcome of a given DOP test can then be predicted by using recently published data bases on RHA penetration to determine the residual penetration into the steel back-up of the DOP test. Results of this methodology, compared to experimental DOP-test results, agree reasonably well for aluminum nitride and silicon carbide, even though scale sizes, impact velocities and experimental procedures varied considerably between investigators. The methodology was then applied to single-valued performance criteria for ceramic armor materials, for example, mass efficiency. This analysis demonstrates that in certain cases, test parameters, like the ratio of penetrator length to ceramic tile thickness, affect test results considerably more than differences between ceramic types. Thus, DOP tests must be properly designed and interpreted in order to assess correctly the ballistic performance of ceramics.
[60] Gama B A, Bogetti T A, Fink B K, Yu C J, Claar T D, Eifert H H, et al.2001.

Aluminum foam integral armor: A new dimension in armor design

. Composite Structures, 52: 381-395.

DOI      URL      摘要

Closed-cell aluminum foam offers a unique combination of properties such as low density, high stiffness, strength and energy absorption that can be tailored through design of the microstructure. During ballistic impact, the foam exhibits significant non-linear deformation and stress wave attenuation. Composite structural armor panels containing closed-cell aluminum foam are impacted with 20-mm fragment-simulating projectiles (FSP). One-dimensional plane strain finite element analysis (FEA) of stress wave propagation is performed to understand the dynamic response and deformation mechanisms. The FEA results correlate well with the experimental observation that aluminum foam can delay and attenuate stress waves. It is identified that the aluminum foam transmits an insignificant amount of stress pulse before complete densification. The ballistic performance of aluminum foam-based composite integral armor (CIA) is compared with the baseline integral armor of equivalent areal-density by impacting panels with 20-mm FSP. A comparative damage study reveals that the aluminum foam armor has finer ceramic fracture and less volumetric delamination of the composite backing plate as compared to the baseline. The aluminum foam armors also showed less dynamic deflection of the backing plate than the baseline. These attributes of the aluminum foam in integral armor system add a new dimension in the design of lightweight armor for the future armored vehicles.
[61] Garcia-Avila M, Portanova M, Rabiei A.2014.

Ballistic performance of a composite metal foam-ceramic armor system

. Procedia Materials Science, 4: 151-156.

DOI      URL      [本文引用: 3]      摘要

Composite Metal Foam is a low-weight, high-strength porous material capable of absorbing great amounts of energy under loading. In this report, Composite Metal Foam panels are manufactured using powder metallurgy technique and 2mm steel hollow spheres in a steel matrix and used in conjunction with a ceramic plate to fabricate a new light-weight composite armor system. This armor system is tested under ballistic loading using 7.62x51mm M80 and 7.62x63mm M2 AP projectiles at varying impact velocities for single and multi-impact scenarios. The material behavior, failure mechanism, and ballistic performance of the armor system are studied for optimization.
[62] Grove D, Rajendran A.2001.

Modeling the interface defeat phenomenon using a physically-based ceramic damage model

. APS Shock Compression of Condensed Matter Meeting Abstracts, 46.

URL      [本文引用: 1]      摘要

This paper presents results from simulations of metallic rods impacting confined ceramic targets. If the ceramic target is properly confined, a phenomenon known as "interface defeat" may occur at a critical impact velocity. When this happens, the projectile is defeated at the ceramic surface, with no penetration into the ceramic. Due to the severe deformations that the projectile experiences during interface defeat, this phenomenon has been traditionally impossible to numerically simulate using conventional Lagrangian finite element algorithms. However, recent advances in particle method techniques have eliminated some of the numerical problems associated with such large deformations. Employing a new generalized particle algorithm option that is now available in the Lagrangian hydrocode EPIC, we simulated several "interface defeat" experimental configurations using the Rajendran-Grove (RG) ceramic model to describe the ceramic material's response to dynamic impact. The purpose of this effort was to evaluate the ability of the RG model to reproduce and predict the phenomenon of interface defeat.
[63] Hallam D, Heaton A, James B, Smith P, Yeomans J.2015.

The correlation of indentation behavior with ballistic performance for spark plasma sintered armour ceramics.

[J]. Eur. Ceram. Soc. 35: 2243-2252.

DOI      URL      [本文引用: 1]      摘要

Abstract The Knoop and Vickers indentation behaviour of spark plasma sintered SiC–5&nbsp;wt.% B4C, B4C and SiC–2.5&nbsp;wt.% AlN–3&nbsp;wt.% C armour ceramics have been investigated and observations correlated with ballistic performance. Surface and sub-surface indentation-induced damage has been characterised via cross-sectioning and serial ceramographic polishing techniques. The nature of the damage appears to be less influential than hardness in relation to ballistic performance, but variability in indentation behaviour appears to correlate with variability in ballistic performance. Examination of the indentation size effect curves shows that both Knoop hardness and predicted transition velocities correlate with V50 ballistic performance against an armour-piercing threat, further supporting the importance of hardness and the potential for indentation to be used as a screening method for armour materials.
[64] Hauver G E, Netherwood P H, Benck R F, Gooch W A, Perciballi W J, Burkins M S.1992.

Variation of target resistance during long rod penetration into ceramics

. 13th Int Symp on Ballistics, 3: 257-264.

[本文引用: 3]     

[65] Hauver G E, Netherwood P H, Benck R F, Kecskes L J.1993.

Ballistic performance of ceramic targets

. Army Symposium on Solid Mechanics, Plymouth, MA, 1: 993.

[本文引用: 1]     

[66] Hauver G E, Netherwood P H, Benck R F, Kecskes L J.1994.

Enhanced ballistic perfomance of ceramics//19th Army Science Conference,

Orlando, FL, 20-24.

[本文引用: 4]     

[67] Hauver G E, Rapacki Jr E J, Netherwood P H, Benck R F.2005.

Interface defeat of long-rod projectiles by ceramic armor

. Army Research Lab Aberdeen Proving Ground Md Weapons and Materials Research Directorate.

[本文引用: 2]     

[68] Hilton C D, W.McCauley J, Swab J J, Shanholtz. E R.2012.

Using hardness tests to quantify bulk plasticity and predict transition velocities in SiC materials

. International Journal of Applied Ceramic Technology, 10: 1-9.

DOI      URL      [本文引用: 2]      摘要

It has long been known that a relation exists between a material's hardness and its gross impact performance; however, the nature of this relationship has not been understood to a degree useful in materials development. Many studies have shown that harder ceramics tend to display better ballistic performance. In addition, some research has suggested that a material's potential for inelastic deformation (or its “quasi-plasticity” – a bulk property) may also play an important role in its resistance to penetration. Methods of quantifying the bulk plasticity of a ceramic material are, however, extremely limited. The current study continues an investigation into a recently proposed technique to (1) quantify bulk quasi-plasticity in SiC materials, and (2) use the “plasticity” value along with a hardness value to predict the transition velocity of potential armor ceramics. The transition velocity values predicted by this approach generally show excellent agreement (within 5% in most cases) with experimentally determined velocities. In addition, the robustness of this predictive technique is demonstrated through the use of multiple operators and multiple hardness testing units.
[69] Holmquist T J, Templeton D W, Bishnoi K D.2001.

Constitutive modeling of aluminum nitride for large strain, high-strain rate, and high-pressure applications

. International Journal of Impact Engineering, 25: 211-231.

DOI      URL      [本文引用: 1]      摘要

This paper presents constitutive modeling of aluminum nitride (AlN) for severe loading conditions that produce large strains, high-strain rates, and high pressures. The Johnson olmquist constitutive model (JH-2) for brittle materials is used. Constants are obtained for the model using existing test data that include both laboratory and ballistic experiments. Due to the wide range of experimental data the majority of constants are determined explicitly. The process of determining constants is provided in detail. The model and constants are used to perform computations of many of the experiments including those not used to generate the constants. The computational results are used to validate the model, provide insight into the response of AlN, and to demonstrate that one set of constants can provide reasonable results over a broad range of experimental data.
[70] Holmquist T J, Johnson G R.2002a.

Response of silicon carbide to high velocity impact

. Journal of Applied Physics, 91:5858-5866.

DOI      URL      [本文引用: 3]      摘要

This article presents an analysis of the response of silicon carbide to high velocity impact. This includes a wide range of loading conditions that produce large strains, high strain rates, and high pressures. Experimental data from the literature are used to determine constants for the Johnson olmquist constitutive model for brittle materials (JH-1). It is possible to directly determine the strength and pressure response of the intact material from test data in the literature. After the ceramic has failed, however, there are not adequate experimental data to directly determine the response of the failed material. Instead, the response is inferred from a comparison of computational results to ballistic penetration test results. After the constants have been obtained for the JH-1 model, a wide range of computational results are compared to experimental data in the literature. Generally, the computational results are in good agreement with the experimental results. Included are computational results that model interface defeat, which occurs when a high velocity projectile impacts a ceramic target and then dwells on the surface of the ceramic with no significant penetration.
[71] Holmquist T J, Johnson G R.2002b.

Modeling ceramic dwell and interface defeat

. Ceramic transactions, 134: 309-316.

[本文引用: 2]     

[72] Holmquist T J, Johnson G R.2003.

Modeling projectile impact onto prestressed ceramic targets

. Journal de Physique IV, 110: 597-602.

DOI      URL      [本文引用: 2]      摘要

This work presents computed results for the responses of ceramic targets, with and without prestress, subjected to projectile impact. Also presented is a computational technique to include prestress. Ceramic materials have been considered for armor applications for many years because of their high strength and low density. Many researchers have demonstrated that providing confinement enhances the ballistic performance of ceramic targets. More recently, prestressing the ceramic is being considered as an additional enhancement technique. This work investigates the effect of prestressing the ceramic for both thin and thick target configurations subjected to projectile impact. In all cases the targets with ceramic prestress provided enhanced ballistic performance. The computed results indicate that prestressed ceramic reduces and/or delays failure, resulting in improved ceramic performance and ballistic efficiency.
[73] Holmquist T J, Johnson G R.2005a.

Characterization and evaluation of silicon carbide for high-velocity impact

. Journal of Applied Physics, 97: 093502.

DOI      URL      [本文引用: 3]      摘要

This article presents a characterization and evaluation of silicon carbide for high-velocity impact. This includes a wide range of loading conditions that produce large strains, high strain rates, and high pressures. Experimental data from the literature are used to determine constants for the Johnson olmquist eissel (JHB) constitutive model for brittle materials. A previous article by the authors presented a characterization of silicon carbide for high-velocity impact using an earlier version of the model (JH-1). The previous work provided good agreement with a broad range of experimental data with the exception of high-velocity penetration data. The current work uses the more recently developed JHB constitutive model, a target geometry that more closely matches the experimental design, and a computational technique that allows for target prestress. These recent developments (primarily the prestress) produce computed results that agree with all the experimental data, including the high-velocity penetration data. The computed results also provide a detailed analysis of the penetration process into a prestressed target and show why it is necessary to include the target prestress. A specific result is the ability to reproduce the nonsteady penetration rate that occurs in the prestressed target.
[74] Holmquist T J, Johnson G R.2005b.

Modeling prestressed ceramic and its effect on ballistic performance

. International Journal of Impact Engineering, 31: 113-127.

DOI      URL      [本文引用: 4]      摘要

This article presents computed results for the responses of ceramic targets, with and without prestress, subjected to projectile impact. Also presented is a computational technique to include prestress. Thin and thick ceramic target configurations are used to understand the effect prestressing has on ballistic performance. For both targets two prestress levels (small and large), and two prestress states (radial and hydrostatic) are investigated. The small prestress is similar in magnitude to values obtained experimentally and the large prestress is approximately the maximum prestress the confinement can produce (determined computationally). The targets are subjected to projectile impact and the resulting ballistic responses are evaluated. In all cases prestressing the ceramic enhanced the ballistic performance, although the effect of the different prestress conditions on the ballistic response was not always obvious.
[75] Holmquist T J, Johnson G R.2008.

Response of boron carbide subjected to high-velocity impact

. International Journal of Impact Engineering, 35: 742-752.

DOI      URL      [本文引用: 4]      摘要

This article presents an evaluation of the response of boron carbide (BC) subjected to impact loading under three different conditions. Condition A is produced by plate-impact experiments where the loading condition is uniaxial strain and the stresses and pressures are high. Under plate-impact loading the material fails at the Hugoniot Elastic Limit (HEL) and the failed material undergoes high confining pressures and relatively small inelastic strains. Condition B is produced by projectile impact onto thick targets where the stresses and pressures are dependent on impact velocity, but they are generally lower than those from plate impact. Under thick-target impact/penetration most of the material fails under compression, the inelastic strains are large and the material appears to exhibit more ductility than under condition A. Lastly, condition C is produced by projectile impact and perforation of thin targets where the stresses and pressures are a combination of compression and tension. Under thin-target perforation the material fails in both tension and compression. The Johnson olmquist eissel (JHB) constitutive model is used to evaluate the material behavior for each of the three conditions, but it is not possible to accurately reproduce the experimental results of the three conditions with a single set of constants. Instead, three different sets of constants are required to accurately model the three impact conditions. These three models/constants are used to provide insight into the complex response of BC, and to identify possible mechanisms that are not included in the JHB model.
[76] Holmquist T J, Johnson G R.2011.

A computational constitutive model for glass subjected to large strains, high strain rates and high pressures

. Journal of Applied Mechanics, 78: 051003.

DOI      URL      [本文引用: 2]      摘要

This article presents a computational constitutive model for glass subjected to large strains, high strain rates and high pressures. The model has similarities to a previously developed model for brittle materials by Johnson, Holmquist and Beissel (JHB model), but there are significant differences. This new glass model provides a material strength that is dependent on the location and/or condition of the material. Provisions are made for the strength to be dependent on whether it is in the interior, on the surface (different surface finishes can be accommodated), adjacent to failed material, or if it is failed. The intact and failed strengths are also dependent on the pressure and the strain rate. Thermal softening, damage softening, time-dependent softening, and the effect of the third invariant are also included. The shear modulus can be constant or variable. The pressure-volume relationship includes permanent densification and bulking. Damage is accumulated based on plastic strain, pressure and strain rate. Simple (single-element) examples are presented to illustrate the capabilities of the model. Computed results for more complex ballistic impact configurations are also presented and compared to experimental data. [DOI: 10.1115/1.4004326]
[77] Holmquist T J, Anderson Jr C E, Behner T.2008.

The effect of a copper buffer on interface defeat//Proceedings of the 24th international symposium on ballistics

, Lancaster. 721-728.

[78] Holmquist T J, Anderson Jr C E, Behner T, Orphal D L.2010.

Mechanics of dwell and post-dwell penetration

. Advances in Applied Ceramics, 109: 467-479.

DOI      URL      摘要

Abstract
[79] Horii H, Nemat-Nasser S.1986.

Brittle failure in compression splitting, faulting and brittle-ductile transition. Philosophical Transaction of the Royal Society of London Series A,

Mathematical and Physical Sciences, 319: 337-374.

DOI      URL      [本文引用: 2]     

[80] Hu X, WANG F, Wang Y, Yu X.2009.

Phenomena of dwell during armour-piercing process

. Materials Review, 1: 024.

DOI      URL      [本文引用: 2]      摘要

Ceramic material with high hardness and light quality is wildly used to protect the light armored vehicles against the threat of small-bore armor-piercing projectile.However,the ability for anti-striking many times of ceramic armour needs to be stronger.During the amour-piericing process,the hardness and intensity of ceramic under confinement condition are increased effectively by the dwell phenomene,then the ability for anti-striking many times of ceramic armour is improved.In this text the definition,microcosmic mechanism,influencing factors of the dwell phenomena and the trends and hotpoint of research are introduced.Finally,the research direction to be focused on numerical simulation and the questions needing to be solved are pointed out.
[81] Iyer K A.2007.

Relationships between multiaxial stress states and internal fracture patterns in sphere-impacted silicon carbide

. International Journal of Fracture, 146: 1-18.

DOI      URL      [本文引用: 1]      摘要

Internal fracture patterns developed in silicon carbide cylindrical targets as a result of dynamic indentation (63 500 m/s) by tungsten carbide spheres are defined. Microscopy of recovered and sectioned targets delineate into three regions, each associated with distinct cracking modes, i.e., shallow cone macrocracking at and near the impact surface, steep interior cone macrocracks that radiate into the target from the impact region and local grain-scale microcracking directly underneath the impact region. The observed fracture patterns are found to maintain a noticeable degree of self-similarity upto the impact velocity of 500 m/s. Linear elastic analysis of the full (surface and interior) stress field developed under static (Hertz) contact loading delineate the target into four regions, based on the number of principal stresses that are tensile (none, 1, 2 or all 3). A strong correlation is found between the principal stress conditions within each region and the forms of cracking, their locations and orientations present therein. This correlation has a number of implications, including non-interaction of crack systems, which are discussed. Illustrative linear elastic fracture mechanics analyses are performed for three regions, and calculated and observed macrocrack lengths are found to be in reasonable agreement.
[82] Jaansalu K M.2013.

Material properties and interface defeat

//27th International Symposium on Ballistics Freiburg, Germany. 1277-1288.

[83] Johnson G R, Holmquist T J.1992.

A computational constitutive model for brittle materials subjected to large strains, high strain rates and high pressures

. Shock Wave and High-Strain-Rate Phenomena in Materials, 1075-1081.

DOI      URL      [本文引用: 1]      摘要

This article presents a computational constitutive model for glass subjected to large strains, high strain rates and high pressures. The model has similarities to a previously developed model for brittle materials by Johnson, Holmquist and Beissel (JHB model), but there are significant differences. This new glass model provides a material strength that is dependent on the location and/or condition of the material. Provisions are made for the strength to be dependent on whether it is in the interior, on the surface (different surface finishes can be accommodated), adjacent to failed material, or if it is failed. The intact and failed strengths are also dependent on the pressure and the strain rate. Thermal softening, damage softening, time-dependent softening, and the effect of the third invariant are also included. The shear modulus can be constant or variable. The pressure-volume relationship includes permanent densification and bulking. Damage is accumulated based on plastic strain, pressure and strain rate. Simple (single-element) examples are presented to illustrate the capabilities of the model. Computed results for more complex ballistic impact configurations are also presented and compared to experimental data. [DOI: 10.1115/1.4004326]
[84] Johnson G R, Holmquist T J.1994.

An improved computational constitutive model for brittle materials

. High-Pressure Science and Technology—993: AIP Publishing. 981-984.

DOI      URL      [本文引用: 1]      摘要

An improved computational constitutive model for brittle materials is presented. It is applicable for brittle materials subjected to large strains, high strain rates and high pressures, and is well锕晆ited for computations in both Lagrangian and Eulerian codes. The equivalent strength is dependent on the intact strength, fractured strength, strain rate, pressure, and damage. The pressure includes the effect of bulking, which is introduced through the transfer of internal energy from decreased shear and deviator stresses to potential internal energy associated with increased hydrostatic pressure. Examples are presented to illustrate the model.
[85] Johnson G R, Holmquist TJ.1999.

Response of boron carbide subjected to large strains, high strain rates, and high pressures

. Journal of Applied Physics, 85: 8060-8073.

DOI      URL      [本文引用: 1]      摘要

This article presents an analysis of the response of boron carbide (B 4C) to severe loading conditions that produce large strains, high strain rates, and high pressures. Experimental data from the literature are used to determine and/or estimate constants for the JH-2 constitutive model for brittle materials. Because B 4C is a very strong material, it is not always possible to determine the constants explicitly. Instead they must sometimes be inferred from the limited experimental data that are available. The process of determining constants provides insight into the constitutive behavior for some loading conditions, but it also raises questions regarding the response under other loading conditions. Several Lagrangian finite element and Eulerian finite difference computations are provided to illustrate responses for a variety of impact and penetration problems
[86] Johnson G R, Holmquist T J, Beissel S R.2003.

Response of aluminum nitride (including a phase change) to large strains, high strain rates, and high pressures

. Journal of Applied Physics, 94: 1639-1646.

DOI      URL      [本文引用: 1]      摘要

This article contains a description of a computational constitutive model for brittle materials subjected to large strains, high strain rates, and high pressures. The focus of this model is to determine the response of aluminum nitride under high velocity impact conditions that produce large strains, high strain rates, and high pressures. The strength is expressed as a function of the pressure, strain rate, and accumulated damage; and it allows for strength of both intact and failed material. The pressure is primarily expressed as a function of the volumetric strain, but it also includes the effect of bulking for the failed material. For materials without a phase change this model is an extension of the previous Johnson olmquist models for brittle materials. The primary new feature of this model is the capability to include a phase change, and this is required for aluminum nitride. Computations are performed to illustrate the capabilities of the model, to compare computed results to experimental results,...
[87] Johnson K L.1987. Contact Mechanics. Cambridge University Press.

[本文引用: 1]     

[88] Jubin G, Fuchi W, Yangwei W, Zhijin Z, Zhuang M.2013.

Effect of back plates on energy dissipation during interface defeat

. Rare Metal Materials and Engineering, 42: 569-573.

URL      [本文引用: 1]     

[89] Krishnan K, Sockalingam S, Bansal S, Rajan S D.2010.

Numerical simulation of ceramic composite armor subjected to ballistic impact

. Composites Part B: Engineering, 41: 583-593.

DOI      URL      摘要

Armor systems made of ceramic and composite materials are widely used in ballistic applications to defeat armor piercing (AP) projectiles. Both the designers and users of body armor face interesting choices – how best to balance the competing requirements posed by weight, thickness and cost of the armor package for a particular threat level. A finite element model with a well developed material model is indispensible in understanding the various nuances of projectile–armor interaction and finding effective ways of developing lightweight solutions. In this research we use the explicit finite element analysis and explain how the models are built and the results verified. The Johnson–Holmquist material model in LS-DYNA is used to model the impact phenomenon in ceramic material. A user defined material model is developed to characterize the ductile backing made of ultra high molecular weight polyethylene (UHMWPE) material. An ad hoc design optimization is carried out to design a thin, light and cost-effective armor package. Laboratory testing of the prototype package shows that the finite element predictions of damage are excellent though the back face deformations are under predicted.
[90] LaSalvia J C.2002a.

A physically-based model for the effect of microstructure and mechanical properties on ballistic performance//26th Annual Conference on Composites, Advanced Ceramics, Materials,

and Structures: A, 213-220.

DOI      URL      [本文引用: 7]      摘要

Summary Recovery of ceramics from ballistic experiments in which impacting ductile long-rod projectiles failed to penetrate has led to the observation and understanding of the localized damage mechanisms beneath the region of impact. The shape of the damaged region indicates that these mechanisms are shear-assisted. Based upon these observations, a model for the transition between no penetration and penetration was formulated by combining a micromechanics -based compressive failure model with Hertz's theory for frictionless contact between axisymmetric linear-elastic bodies. The resulting model indicates the relative significance of a ceramic's grain size, short-crack fracture toughness, yield strength, Poisson's ratio, coefficient of friction, and critical crack-length on the dwell/penetration transition. A brief review of the derivation and predictions of the model are presented.
[91] LaSalvia J C.2002b.

Recent progress on the influence of microstructure and mechanical properties on ballistic performance

. Ceramic Transactions, 134: 557-570.

[本文引用: 1]     

[92] LaSalvia J C.2005a.

Effect of ceramic thickness on the dwell/penetration transition phenomenon

. Ballistics 2005: 22nd International Symposium on Ballistics: DEStech Publications, Inc. 726.

[本文引用: 3]     

[93] LaSalvia J C.2005b.

A predictive model for the dwell/penetration transition phenomenon//Proceeding of the 22th International Symposium on

Ballistics, Canada, 717-725.

[本文引用: 3]     

[94] LaSalvia J C, Normandia M J.2002.

An analytical prediction for the effect of ceramic thickness and mechanical properties on the dwell/penetration transition velocity//20th International Symposium on Ballistics

.

[本文引用: 2]     

[95] LaSalvia J C, McCauley J W.2010.

Inelastic deformation mechanisms and damage in structural ceramics subjected to high-velocity impact

. International Journal of Applied Ceramic Technology, 7: 595-605.

DOI      URL      [本文引用: 5]      摘要

The inelastic deformation mechanisms and damage features observed in structural ceramics subjected to nonpenetrating, high-velocity impacts are similar to those seen in quasistatic Hertzian indentation, albeit more severe. For impacts on large ceramic bodies (relative to impactor diameter), cone cracking is the primary mechanism in regions of high tensile stresses. In regions of nonhydrostatic compressive stresses, depending on the material characteristics, elasticity, grain-boundary microcracking, or plasticity are the primary mechanisms, and depending on their associated energetics, may be able to compete with the initiation and growth of cone cracks. In this regard, a new model is presented that examines the effect of grain-boundary microcracking on cone cracking through shear-induced dilatancy (i.e., bulking) within the quasiplastic zone that forms just underneath the impact site. Depending on the size of the quasiplastic zone and bulking pressure, it is shown that the bulking phenomenon has the potential to suppress cone cracking. Lastly, examples of other shear-driven inelastic deformation mechanisms are presented.
[96] LaSalvia J C, Horwath E J, Rapacki E J, Shih C J, Meyers M A.

2001. Microstructural and micromechanical aspects of ceramic long-rod projectiles interactions: Dwell/penetration transitions

//Proceedings of theExplomet 2000, 437-446.

[本文引用: 5]     

[97] LaSalvia J C, Normandia M J, Miller H T, Mackenzie D E.2005.

Sphere impact induced damage in ceramics II. Armor-grade B4C and WC

. Advances in Ceramic Armor, 183-192.

DOI      URL      [本文引用: 2]      摘要

ABSTRACT Armor-grade B4C and WC cylinders (25.4 mm 25.4 mm) were impacted with WC-6Co (6 wt.% Co) spheres (6.35 mm diameter) at velocities between 100 m/s and 400 m/s. The recovered cylinders were subsequently sectioned and metallographically-prepared to reveal the dominant sub-surface damage types and change in damage severity as a function of impact velocity. In general, both ceramics exhibited radial, ring, Hertzian cone, and lateral cracks which increased in number and length as the impact velocity increased. The cracking was predominately transgranular for B4C and intergranular for WC. However, unlike SiC and TiB2 (reported in the part I[1]), no evidence of a comminuted region directly beneath the impact center was observed in either ceramic. B4C exhibited severe spallation of material surrounding the impact center. In addition, evidence of shear localization beneath the impact center was also observed. This observation may in part explain the sharp drop in shear strength that B4C exhibits in plate impact experiments when shocked above 20 GPa. In contrast, WC was almost unremarkable in its response to being impact with the WC spheres in that it exhibited a nice spherical crater that is more typical of the response of a metal. The effect of impact velocity on the observed damage and differences in damage between these two armor-grade ceramics will be presented.
[98] LaSalvia J C, McCuiston R C, Fanchini G, McCauley J W, Chhowalla M, Miller H T, et al.2007.

Shear localization in a sphere-impacted armor-grade boron carbide

//23rd International Symposium on Ballistics Tarragona, Spain, 1329-1337.

[本文引用: 2]     

[99] LaSalvia J C, Leavy B, Miller H T, Houskamp J R, McCuiston R C.2009.

Recent results on the fundamental performance of a hot-pressed silicon carbide impacted by sub-scale long-rod penetrator

. Advances in Ceramic Armor IV, 89-97.

DOI      URL      [本文引用: 1]      摘要

Summary This chapter contains sections titled: Abstract Introduction Experimental Set-Up & Procedures Experimental Results and Discussion Summary & Conclusions Acknowledgements References
[100] LaSalvia J C, Leavy R B, Houskamp J R, Miller H T, MacKenzie D E, Campbell J.2010a.

Ballistic impact damage observations in a hot-pressed boron carbide

. Advances in Ceramic Armor V, 45-55.

DOI      URL      [本文引用: 2]      摘要

ballistic impact damage observations in a hot-pressed boron carbidercial hot-pressed boron carbide (B4C) impacted ballistically are reported. The ballistic targets con
[101] LaSalvia J C, Campbell J, Swab J, McCauley J.2010b.

Beyond hardness: Ceramics and ceramic-based composites for protection

. JOM, 62: 16-23.

DOI      URL      [本文引用: 4]      摘要

Because of their lightweight and high hardness, ceramics have been successfully used in protection technologies for over 40 years. The high hardness of a ceramic enables it to break, fragment, and deform impacting projectiles. This paper deals with a number of issues connected to the application of ceramics to ballistic protection, including ceramic hardness, inelastic deformation mechanisms, basic ballistic phenomenology and experimentation, ceramic damage due to ballistic impact, performance/failure maps based upon specific damage/failure mechanisms, and what possible future types of ceramics the suppression of these damage/failure mechanisms guide us to.
[102] Leavy B, Rickter B, Normandia M J.2008.

Modeling dynamically impacted ceramic material experiments

//Advances in Ceramic Armor: A Collection of Papers Presented at the 29th International Conference on Advanced Ceramics and Composites, January 23-28, 2005, Cocoa Beach, Florida, Ceramic Engineering and Science Proceedings: Wiley-American Ceramic Society. 11.

DOI      URL      摘要

ABSTRACT SummaryA number of new experimental techniques were developed to simplify the process of calibrating ceramic constitutive models. Current ceramic model calibration techniques for the Johnson-Holmquist One (JH1) model require the use of complicated penetration experiments to tune the damage evolution to a specific experiment Application of these ceramic models to different experiments often illustrates discrepancies in the results.This paper will illustrate the use of data from these new experimental methods to simplify the calibration process for hot-pressed silicon carbide (SiC), and thus more accurately capture the behavior of different ceramic materials. Dynamic sphere impacts as well as kinetic energy rod penetration rate study programs have been established. Comparison of the experimental data with the corresponding simulation results will highlight areas for improvement in ceramic modeling. Specifically, the macroscopic behavior the constitutive model attempts to encompass and its relation to relevant static and dynamic properties.
[103] Li J C, Chen X W.2017.

Theoretical analysis of projectile-target interface defeat and transition to penetration by long rods due to oblique impacts of ceramic targets

. International Journal of Impact Engineering, 106: 53-63.

DOI      URL      [本文引用: 3]     

[104] Li J C, Chen X W, Ning F.2014.

Comparative analysis on the interface defeat between the cylindrical and conical-nosed long rods

. International Journal of Protective Structures, 5: 21-46.

DOI      URL      [本文引用: 3]     

[105] Li J C, Chen X W, Ning F, Li X L.2015.

On the transition from interface defeat to penetration in the impact of long rod onto ceramic targets

. International Journal of Impact Engineering, 83: 37-46.

DOI      URL      [本文引用: 3]      摘要

61Three deformation modes of the long rod and the ceramic target are summarized.61The critical impact velocity range for the transition is further identified.61Critical transition time is analyzed and an analytical expression is formulated.61The analytical formula is convenient for the engineering application.
[106] Liu T, Fleck N A, Wadley H N G, Deshpande V S.2013.

The impact of sand slugs against beams and plates: Coupled discrete particle/finite element simulations

. Journal of the Mechanics and Physics of Solids, 61: 1798-1821.

DOI      URL      [本文引用: 2]      摘要

The impact of a slug of dry sand particles against a metallic sandwich beam or circular sandwich plate is analysed in order to aid the design of sandwich panels for shock mitigation. The sand particles interact via a combined linear-spring-and-dashpot law whereas the face sheets and compressible core of the sandwich beam and plate are treated as rate-sensitive, elastic–plastic solids. The majority of the calculations are performed in two dimensions and entail the transverse impact of end-clamped monolithic and sandwich beams, with plane strain conditions imposed. The sand slug is of rectangular shape and comprises a random loose packing of identical, circular cylindrical particles. These calculations reveal that loading due to the sand is primarily inertial in nature with negligible fluid–structure interaction: the momentum transmitted to the beam is approximately equal to that of the incoming sand slug. For a slug of given incoming momentum, the dynamic deflection of the beam increases with decreasing duration of sand-loading until the impulsive limit is attained. Sandwich beams with thick, strong cores significantly outperform monolithic beams of equal areal mass. This performance enhancement is traced to the “sandwich effect” whereby the sandwich beams have a higher bending strength than that of the monolithic beams. Three-dimensional (3D) calculations are also performed such that the sand slug has the shape of a circular cylindrical column of finite height, and contains spherical sand particles. The 3D slug impacts a circular monolithic plate or sandwich plate and we show that sandwich plates with thick strong cores again outperform monolithic plates of equal areal mass. Finally, we demonstrate that impact by sand particles is equivalent to impact by a crushable foam projectile. The calculations on the equivalent projectile are significantly less intensive computationally, yet give predictions to within 5% of the full discrete particle calculations for the monolithic and sandwich beams and plates. These foam projectile calculations suggest that metallic foam projectiles can be used to simulate the loading by sand particles within a laboratory setting.
[107] Lundberg P.2004.

Interface defeat and penetration: Two modes of interaction between metallic projectiles and ceramic targets

. [PhD Thesis]. Uppsala University.

[本文引用: 13]     

[108] Lundberg P.2007.

Research in sweden on dwell in ceramics

. Advances in Ceramic Armor III: Ceramic and Engineering Science Proceedings, 28: 1-18.

DOI      URL      [本文引用: 5]      摘要

Summary This chapter contains sections titled: Introduction Dwell and Interface Defeat Experimental Techniques Projectile and Target Materials Used Modelling and Analyses Transition Velocity Versus Material Properties and Confinement Transition Velocity Versus Projectile Geometry Discussion Conclusions Future Research Acknowledgments
[109] Lundberg P, Lundberg B.2005.

Transition between interface defeat and penetration for tungsten projectiles and four silicon carbide materials

. International Journal of Impact Engineering, 31: 781-792.

DOI      URL      [本文引用: 4]     

[110] Lundberg P, Westerling L, Lundberg B.1996.

Influence of scale on the penetration of tungsten rods into steel-backed alumina targets

. International journal of impact engineering, 18: 403-416.

DOI      URL      [本文引用: 1]      摘要

As ballistic tests are often performed in reduced geometrical scale, the scaling laws are important for the interpretation of the results. In this study, we tested the validity of replica scaling, by which we mean that all geometrical dimensions are scaled uniformly, while the materials and the impact velocity are kept the same. Long tungsten projectiles with length-to-diameter ratio 15 were fired against unconfined alumina targets with steel backing. The tests were carried out with impact velocities 1500 m sand 2500 m s, and in three different scales with projectile lengths 30, 75 and 150 mm (diameters 2, 5 and 10 mm). The alumina targets were photographed by means of a high-speed camera, and the tungsten projectiles were photographed inside the alumina targets by means of flash radiography. Also, the residual penetrations in the steel backings were measured. The Johnson-Holmquist model for ceramic materials was implemented into the AUTODYN code, which was used for simulation of the experiments. The agreement between results of experiment and simulation was fair, and over the tested interval of scales replica scaling was found to be valid with reasonable accuracy.
[111] Lundberg P, Renström R, Lundberg B.2000.

Impact of metallic projectiles on ceramic targets transition between interface defeat and penetration

. International Journal of Impact Engineering, 24: 259-275.

DOI      URL      [本文引用: 10]      摘要

Armour systems capable of defeating an incoming projectile on the surface of a ceramic have been reported by several authors. This capability, called interface defeat, signifies that the projectile material is forced to flow radially outwards on the surface of the ceramic without penetrating significantly. In order to investigate the conditions for interface defeat, two models for the interaction of a metallic projectile and a ceramic target were established. With the aid of them, upper and lower bounds for the transition impact velocity between interface defeat and normal penetration were estimated for a given combination of metallic projectile and ceramic target. These approximate bounds were found to be consistent with transition velocities determined experimentally for two projectile materials (tungsten and molybdenum) and five target materials (two types of silicon carbide, boron carbide, titanium diboride and a polycrystalline diamond composite).
[112] Lundberg P, Renström R, Holmberg L.2001.

An experimental investigation of interface defeat at extended interaction time

//19th International Symposium of Ballistics Interlaken, Switzerland, 1463-1469.

[本文引用: 4]     

[113] Lundberg P, Renström R, Lundberg B.2006.

Impact of conical tungsten projectiles on flat silicon carbide targets: Transition from interface defeat to penetration

. International Journal of Impact Engineering, 32: 1842-1856.

DOI      URL      [本文引用: 5]      摘要

Normal impact of conical tungsten projectiles on flat silicon carbide targets was studied experimentally and numerically for half apex angles 5 and 5 15 , respectively, and comparisons were made with cylindrical projectiles. A 30 mm powder gun and two 150 kV and four 450 kV X-ray flashes were used in the impact tests. The numerical simulations were run with the Autodyn code in two steps. In the first, the surface loads were determined for different impact velocities under assumed condition of interface defeat. In the second, these surface loads were applied to the targets in order to obtain critical states of damage and failure related to the transition between interface defeat and penetration, and the corresponding critical velocities. In the impact tests, interface defeat occurred below a transition velocity, which was significantly lower for the conical than for the cylindrical projectiles. Above the transition velocity, the initial penetration of conical projectiles differed markedly from that usually observed for cylindrical projectiles. It occurred along a cone-shaped surface crack, qualitatively corresponding to surface failure observed in the simulations. The transition velocity for the conical projectile was found to be close to the critical velocity associated with this surface failure.
[114] Lundberg P, Renström R, Andersson O.2013.

Influence of length scale on the transition from interface defeat to penetration in unconfined ceramic targets

. Journal of Applied Mechanics, 80: 031804.

DOI      URL      [本文引用: 12]      摘要

One observation from interface defeat experiments with thick ceramic targets is that confinement and prestress becomes less important if the test scale is reduced. A small unconfined target can show similar transition velocity as a large and heavily confined target. A possible explanation for this behavior is that the transition velocity depends on the formation and growth of macro cracks. Since the crack resistance increases with decreasing length scale, the extension of a crack in a small-scale target will need a stronger stress field, viz., a higher impact velocity, in order to propagate. An analytical model for the relation between projectile load, corresponding stress field, and the propagation of a cone-shaped crack under a state of interface defeat has been formulated. It is based on the assumption that the transition from interface defeat to penetration is controlled by the growth of the cone crack to a critical length. The model is compared to experimentally determined transition velocities for ceramic targets in different sizes, representing a linear scale factor of ten. The model shows that the projectile pressure at transition is proportional to one over the square root of the length scale. The experiments with small targets follow this relation as long as the projectile pressure at transition exceeds the bound of tensile failure of the ceramic. For larger targets, the transition will become independent of length scale and only depend on the tensile strength of the ceramic material. Both the experiments and the model indicate that scaling of interface defeat needs to be done with caution and that experimental data from one length scale needs to be examined carefully before extrapolating to another.
[115] Lundberg P, Renström R, Andersson O.2016.

Influence of confining prestress on the transition from interface defeat to penetration in ceramic targets

. Defence Technology, 12: 263-271.

DOI      URL      [本文引用: 6]      摘要

Replica scaled impact experiments with unconfined ceramic targets have shown that the transition velocity, i.e., the impact velocity at which interface defeat ceases and ceramic penetration occurs, decreased as the length scale increased. A possible explanation of how this scale effect is related to the formation of a cone crack in the ceramic has been presented by the authors in an earlier paper. Here, the influence of confinement and prestress on cone cracking and transition velocity is investigated. The hypothesis is that prestress will suppress the formation and growth of the cone crack by lowering the driving stress. A set of impact experiments has been performed in which the transition velocity for four different levels of prestress has been determined. The transition velocities as a function of the level of confining prestress is compared to an analytical model for the influence of prestress on the formation and extension of the cone crack in the ceramic material. Both experiments and model indicate that prestress has a strong influence on the transition from interface defeat to penetration, although the model underestimates the influence of prestress.
[116] Malaise F, Tranchet J Y, Collombet F, Furnish M D, Chhabildas L C, Hixson R S.2000.

Effects of a dynamic confinement on the penetration resistance of ceramics against long rods

. AIP Conference Proceedings: AIP, 1121-1124.

DOI      URL      摘要

Adequate confinement of a ceramic block can lead to its impenetrability against long rod penetrators. New ballistic experiments (encapsulated rod experiments) enabling a pressurization of the front face of the ceramic block (dynamic confinement) have been performed and compared to results obtained from standard unconfined configurations (DOP tests). Impenetrability of the ceramic block is obtained with the encapsulated rod configuration. A modeling approach based on a description of the fragmentation process of the ceramic is proposed. In particular, effects of the void content of the fragmented ceramic on its shear resistance are taken into account. Comparisons between Eulerian computation and the experiments show that conditions for rod dwell are linked to immobilizing fragments of ceramic in front of the projectile.
[117] McCauley J W, Wilantewicz T E.2009.

Using plasticity values determined from systematic hardness indentation measurements for predicting impact behavior in structural ceramics: A new, simple screening technique

. Army Research Lab Aberdeen Proving Ground Md Weapons and Materials Research Directorate.

[118] McGlaun M J, Thompson S L, Elrick M G.1990.

CTH: A three-dimensional shock wave physics code

. International Journal of Impact Engineering, 10: 351-360.

DOI      URL      摘要

http://linkinghub.elsevier.com/retrieve/pii/0734743X90900713
[119] Meyer E.1908.

Investigations of hardness testing and hardness

. Phys Z, 9: 66.

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[120] Meyer Jr H W, Abeln T, Bingert S, Bruchey W J, Brannon R M, Chhabildas L C, et al.2000.

Crack behavior of ballistically impacted ceramic

. Shock Compression of Condensed Matter, 505: 1109-1112.

DOI      URL     

[121] Normandia M J.2004.

Impact response and analysis of several silicon carbides

. International Journal of Applied Ceramic Technology, 1: 226-234.

DOI      URL      [本文引用: 1]      摘要

Several hot-pressed and sintered SiC variants were impacted with tungsten-carbide (WC) spheres at velocities up to 1700 m/s. Ballistic response curves of areal density penetrated as a function of impact velocity were generated to compare ceramics for ballistic applications. Observed response curve features are shown to be similar to those observed for metal impacts. Ballistics penetration models that captured these features for metal targets were utilized to analyze the ceramic data. Visual examination of damage type and extent suggested that cavity expansion expressions for target resistance might help to quantify the strength of fully confined, damaged, comminuted ceramics. The experimental results, visual observations, and preliminary analysis using a ballistics penetration model are presented.
[122] Orphal D L.1997.

Phase three penetration

. International Journal of Impact Engineering, 20: 601-616.

DOI      URL      [本文引用: 2]     

[123] Orphal D L, Franzen R R.1997.

Penetration of confined silicon carbide targets by tungsten long rods at impact velocities from 1.5 to 4.6km/s

. International Journal of Impact Engineering, 19: 1-13.

DOI      URL      [本文引用: 1]      摘要

A series of 27 terminal ballistics experiments were performed to measure the penetration of long tungsten rods against confined silicon carbide targets. Impact velocities ranged from 1.5 to about 4.6 km/s. The experiments were performed in the reverse ballistic mode using a two-stage light-gas gun. Penetrator diameter, D , was 0.762 mm (0.030 in). The length to diameter ratio for the penetrator was LD = 20 for nearly all the tests and never less than LD = 15. Primary instrumentation for these experiments was four independently timed, 450 kV flash X-rays. These X-rays provided four views of the penetrator-target interaction during the penetration event from which the following data were determined: p = penetration depth as a function of time , L r = remaining length of penetrator as a function of time, as well as target hole geometry, spatial distribution of the eroded rod material, etc. From these data u = dpdt = speed of penetration into the target, vc = d(L 61 Lr)dt = speed of “consumption” of the long rod, were obtained, as well as final penetration depth.
[124] Orphal D L, Franzen R R, Piekutowski A J, Forrestal M J.1996.

Penetration of confined aluminum nitride targets by tungsten long rods at 1.5-4.5km/s

. International Journal of Impact Engineering, 18: 355-368.

DOI      URL      [本文引用: 1]      摘要

http://linkinghub.elsevier.com/retrieve/pii/0734743X9500045C
[125] Orphal D L, Franzen R R, Charters A C, Menna T L, Piekutowski A J.1997.

Penetration of confined boron carbide targets by tungsten long rods at impact velocities from 1.5 to 5.0km/s

. International Journal of Impact Engineering, 19: 15-29.

DOI      URL      摘要

Forty terminal ballistics experiments were performed to measure the penetration of simple confined boron carbide targets by long tungsten rods. Impact velocities ranged from 1.5 to about 5.0km/s. The experiments were performed in the reverse ballistic mode using a two-stage light-gas gun. For tests with velocities 1.493≤v≤2.767km/s, the penetrator diameter was 1.02mm (0.040inch). For tests with impact velocities v≥2.778km/s the penetrator diameter was 0.762mm (0.030 inch). For tests in the velocity range 2.335 < v< 2.761 km/s both penetrator sizes were used. The length-to-diameter ratio for the penetrator was L/D = 20 for all but the three highest velocity tests; in these three tests L/D = 15. Primary instrumentation for these experiments was four independently timed, 450 kV flash X-rays. These X-rays provided four views of the penetrator-target interaction during the penetration event from which he following data were determined: p = penetration depth as a function of time, L
[126] Partom Y.2011.

Modeling interface defeat and dwell in long rod penetration into ceramic

. Shock Compression of Condensed Matter, 1426: 76-79.

DOI      URL      摘要

When a long rod projectile hits a ceramic target, the projectile may sometimes dwell at the target boundary and flow radially. This dwell or interface defeat phenomenon has to do with the dynamic failure process of the ceramic target material. As ceramics are brittle materials, what is needed to model dwell, is a realistic model for dynamic failure of brittle materials. A "standard" such model is the so called JH model (which has several versions). According to JH the material accumulates damage as a function of the effective plastic strain, which is a ductile response feature. Brittle materials are not supposed to accumulate plastic strain before they're fully failed. To model dwell we therefore propose here a different failure model. We call it BSF (= Brittle Shear Failure), and it is based on the Overstress (or overload) principle. Our BSF model is rather simple, has a small number of adjustable parameters, and is readily calibrated. We implement the model in a hydro-code and demonstrate how it works for a typical example of dwell situation. In the example, a long steel rod impacts an AD995 alumina target with and without a copper buffer.
[127] Pickering E, O'Masta M, Wadley H, Deshpande V.2016.

Effect of confinement on the static and dynamic indentation response of model ceramic and cermet materials

. International Journal of Impact Engineering, 110: 123-137.

DOI      URL      [本文引用: 1]      摘要

The effect of confinement on the localized impact response of ceramic and cermet tiles is investigated. A scoping study was first conducted using alumina and TiC/Ni cermet tiles encased in a metal matrix composite (MMC) and impacted by high velocity steel balls. The investigation revealed that increasing the MMC casing thickness reduced the cracking in the ceramic (alumina) tile but had a much smaller effect on the cermet tile. This motivated a detailed experimental investigation of the effect of lateral confining pressure on the static and dynamic indentation response of granite and Corian ; tiles that serve as model ceramic and cermet materials, respectively. Quasi-static indentation resulted in comminution under the indenter and the formation of radial cracks in the granite tiles, with the number of radial cracks decreasing with increasing confining pressure. By contrast, the plastic indentation and small shallow radial cracks observed in the Corian ; tiles were unaffected by variations in the confining pressure. The loading imposed by the high velocity impact of a steel ball resulted in conical and lateral cracks as well as radial cracks and comminution in the granite tiles. Intriguingly, while the cone and radial cracks were suppressed by confining pressure, the lateral cracks appeared only at the higher confining pressures. By contrast, the strain rate sensitivity of the yield strength of the Corian ; reduced the plastic indentation under dynamic loading, but this in turn promoted the formation of radial cracks which decreased in number with increasing confining pressure. No lateral cracks, conical cracks or comminution was observed in the Corian ; . The study shows that confining pressure has a less significant effect on cermets compared to ceramics. Since confinement systems add considerable weight to ceramic-based ballistic protection systems, this study suggests that the use of lightly confined cermets could reduce the overall weight of ballistic protection systems.
[128] Pickup I, Barker A, Chenari R, James B, Hohler V, Weber K, et al.2002.

Aspects of geometry affecting the ballistic performance of ceramic targets

. Ceramic transactions, 134: 643-650.

[本文引用: 1]     

[129] Pickup I, Barker A, Elgy I, Peskes G, van der Voorde M.2004.

The effect of coverplates on the dwell characteristics of silican carbide subject to KE impact. International Symposium on Ballistics,

Adelaide, Australia, 19-23.

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[130] Quan X, Clegg R A, Cowler M S, Birnbaum N K, Hayhurst C J.2006.

Numerical simulation of long rods impacting silicon carbide targets using JH-1 model

. International Journal of Impact Engineering, 33: 634-644.

DOI      URL      [本文引用: 1]      摘要

The Johnson–Holmquist model for simulating impact and penetration into ceramic and glass materials is commonly used in continuum hydrocodes. There are two forms of the Johnson–Holmquist ceramic model: JH-1 using a segmented linear approximation to the strength envelope with instantaneous failure; JH-2 using a smooth analytic approximation to the strength envelope with damage-induced strength reduction. Both these models are now implemented in the AUTODYN 03 software. The validation of the JH-1 model is presented in this paper by comparing numerical predictions with experimental data. The failure parameters of the JH-1 model are also validated in the current numerical approach. Good agreement between numerical predictions and experimental measurements is shown for the behavior of silicon carbide in various impact situations. Time histories of particle velocity in compressive and tensile spall plate impact, interface dwell in confined impact, and total penetration depth in oblique impact are used in the comparison. The JH-1 model in AUTODYN is shown to be a powerful numerical tool in the design and analysis of ceramic armor systems.
[131] Rabiei A.2014.

Materials with Improved Absorption of Collision Forces for Railroad Cars

.

URL      [本文引用: 1]      摘要

The purpose of this project is to develop and perform an extensive experimental and numerical investigation and evaluate the dynamic properties of composite metal foams (CMF) at various impact speeds. This will include different speeds mimicking those of railroad car collisions, at different speeds, including high speeds. This investigation will provide the fundamental understanding of the behavior of CMF that is of critical importance before composite metal foams can be implemented effectively to increase protection against hazards and damage in potential railroad car collisions. The outcome of this work could lead to safer and more efficient railroad car safety structures along with less weight. The reduced weight of these components could also help to lower costs for production and operation and improve fuel economy.
[132] Rajendran A.1994.

Modeling the impact behavior of AD85 ceramic under multiaxial loading

. International Journal of Impact Engineering, 15: 749-768.

DOI      URL      [本文引用: 1]      摘要

This report presents an advanced constitutive model to describe the complex behavior of ceramic materials under impact loading conditions. The governing equations utilize a set of microphysically based constitutive relationships to model deformation and damage processes in a ceramic. The total strain is decomposed into elastic, plastic, and microcracking components. The model parameters for AD85 ceramic were determined using the data from split Hopkinson bar (SHB) and bar-on-bar experiments under uniaxial stress state and plate impact experiment under uniaxial strain state. To further validate the generality of the model parameters, modeling of a diagnostic ballistic experiment in which a steel projectile impacted an AD85 ceramic front-faced thick aluminum plate was considered. In this experiment, stress histories were measured in the target by embedded manganin and carbon stress gauges. The results from the numerical simulations of the ballistic experiment using a shock wave propagation based finite element code successfully matched the measured stress history.
[133] Rajendran A, Grove D.1996. Determination of Rajendran-Grove ceramic constitutive model constants//Pro- ceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter: AIP Publishing. 539-542.

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[134] Renström R, Lundberg P, Lundberg B.2004.

Stationary contact between a cylindrical projectile and a flat target surface under conditions of dwell

. International Journal of Impact Engineering, 30: 1265-1282.

DOI      URL      [本文引用: 4]      摘要

Armour systems capable of defeating an incoming projectile on the surface of a ceramic target have been reported. This capability, called interface defeat or dwell, signifies that the projectile material is forced to flow radially on the surface of the target without penetrating significantly. Under such flow conditions, the hydrodynamic pressure is normally the most important part of the normal load on the target surface. Therefore, projectile properties such as yield strength and compressibility are commonly ignored or assumed to contribute only marginally. In order to investigate the effects of these properties, an analytical expression was derived for the normal load from a cylindrical metallic projectile impacting on a flat, rigid and friction-free surface, which includes the contributions from yield strength and compressibility in addition to that of inertia. At an impact velocity representative of today's ordinance velocities, the contributions to load intensity on the axis from yield strength and compressibility were found to be 15% and 3.4%, respectively, of that of inertia. The analytical results and Autodyn-2D numerical simulations show good agreement within a projectile radius from the axis.
[135] Renström R, Lundberg P, Lundberg B.2009.

Self-similar flow of a conical projectile on a flat target surface under conditions of dwell

. International Journal of Impact Engineering, 36: 352-362.

DOI      URL      摘要

In order to investigate the state of stress in a target material under conditions of interface defeat or dwell it is necessary to determine the load intensity at the interface of the flowing projectile material and the target. Previous studies for a cylindrical projectile geometry at normal impact under stationary conditions show that the load can be considered to be composed of three components, viz., those of inertia, compressibility and yield strength of the projectile material. In order to determine the influence of projectile shape, a conical projectile in axi-symmetric impact on a ridged, friction-free surface is studied by use of an analytical model for self-similar flow and numerical Autodyn simulations. It is shown how the maximum load intensity, and the position of the maximum, depends on the apex angle. Both the self-similar model and the Autodyn simulations show that the contribution to the load intensity from compressibility is positive below and negative above apex angles 80 . The influence of yield strength on the load intensity depends only weakly on the apex angle and therefore corresponds to that for a cylindrical projectile.
[136] Roberson C, Hazell P.2003.

Resistance of different ceramic materials to penetration by a tungsten carbide cored projectile

. Ceramic Armor and Armor Systems, 151: 153-163.

DOI      URL      [本文引用: 2]      摘要

Summary This chapter contains sections titled: Introduction Experimental Results Discussion Conclusions Acknowldegement
[137] Rosenberg Z, Tsaliah J.1990.

Applying Tate's model for the interaction of long rod projectiles with ceramic targets

. International Journal of Impact Engineering, 9: 247-251.

DOI      URL      [本文引用: 1]      摘要

The penetration of ceramic tiles by long rod penetrators is discussed in terms of the modified hydrodynamic theory of A. Tate which was developed for thick metallic targets. The resistance of the tile to penetration is determined with the threshold velocity for the penetration of a very large ceramic block. According to Tate's theory, the threshold impact velocity for a given projectile (with a well defined strength) depends only on the tile's resistance to penetration. We show here that using three different projectiles (copper, steel and tungsten) resulted in the same value for this parameter for thick alumina tiles. This fact strongly enhances the idea of applying Tate's theory to ceramics. A different set of experiments, with relatively thin tiles bonded to thick steel plates, was performed determining penetration depths of the long rods into the steel backing. These were compared with predictions based on Tate's model using the values for the penetration resistance, which were determined by thick tile experiments. The good agreement can be considered as a further confirmation of our main thesis. Resistance of penetration parameters ( R t) were determined for other ceramics (silicon carbide, titanium diboride, etc.) by measuring the penetration depths of the long rod projectile into the thick backing and using Tate's model with R t as a parameter.
[138] Savio S, Ramanjaneyulu K, Madhu V, Bhat TB.2011.

An experimental study on ballistic performance of boron carbide tiles

. International Journal of Impact Engineering, 38: 535-341.

DOI      URL      摘要

Boron carbide is an attractive candidate for use as armour material because of its lower density combined with high hardness. The ballistic performance of boron carbide tiles were evaluated using standard Depth of Penetration (DOP) test method against hard steel 7.6202mm armour piercing (AP) projectiles. The effect of variation in thickness of tile and the projectile velocity on the ballistic efficiency of the material was studied. It has been found that the differential efficiency factor (DEF) increases with increase in projectile velocity from 600 to 82002m/s. And an insignificant or marginal increase in efficiency was observed for increase in tile thickness from 5.202mm up to 7.302mm. The effect of the type of radial confinement on the residual DOP was also studied. It was found that the steel radial confinement produces lower residual DOP values compared to aluminium alloy and with no radial confinement. Results along with photographs have been presented.
[139] Serjouei A.2014.

Modelling and analysis of bi-layer ceramic-metal protective structures

. [PhD Thesis]. Singapore:Nanyang Technological University (NTU).

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[140] Serjouei A, Gour G, Zhang X, Idapalapati S, Tan G E B.2016.

On improving ballistic limit of bi-layer ceramic-metal armor

. International Journal of Impact Engineering, 105: 54-67.

DOI      URL      [本文引用: 1]      摘要

This paper investigates experimentally and numerically methods to enhance the ballistic performance of ceramic armor. Initially we demonstrate an experimental set-up to impose pre-stress to ceramic-metal bi-layer armor and study the depth of penetration to measure the ballistic efficiency as a function of pre-stress intensity validating our previous numerical studies on effect of pre-stress on the ballistic limit of ceramic armor (Int. Journal of Impact Engineering, 2015(84)159-170). Secondly, a module is designed and tested to achieve interface defeat in ceramic armor with multiple interface layers. Finally, influence of thickness of the steel cover plate (CP) on ballistic performance of SiC ceramic is studied through AUTODYN finite element simulations for normal and oblique (NATO 60 ) against long rod projectile (LRP) with a conical tip. The LRP and CP are modeled using smooth particle hydrodynamic (SPH) particles and rest of the component is modeled using Lagrangian domain. The numerical analyses of armor modules are compared via depth of penetration (DOP) and LRP residual length for varying cover plate thicknesses.
[141] Simha C H M, Bless S, Bedford A.2002.

Computational modeling of the penetration response of a high-purity ceramic

. International Journal of Impact Engineering, 27: 65-86.

DOI      URL      摘要

This paper describes computational modeling of the penetration response of a high-purity ceramic, namely the AD-99.5 alumina. This material is the most widely investigated ceramic, and extensive materials testing and ballistic data are available. The model development is based on constitutive relationships inferred from bar impact and plate impact data. The model is then incorporated into the EPIC Lagrangian finite element code. A novel element removal scheme for ceramics is presented, and the code is then used to investigate the penetration response of AD-99.5 alumina in the depth of penetration and semi-infinite configurations. The computations are found to be in excellent agreement with the experimental results. The interface defeat problem is also investigated numerically, and the results are used to suggest an explanation for interface defeat.
[142] Sternberg J.1989.

Material Properties Determining the resistance of ceramics to high velocity penetration

. Journal of Applied Physics, 65: 3417-3424.

DOI      URL      [本文引用: 1]      摘要

The relationships between target material properties and the target strength term in the analytic representation of impact is examined. For ductile materials hardness is closely related to the magnitude of the strength term. It is shown that the key parameters correlating microhardness measurements in ceramics are similar to those for ductile materials. However, the strength terms that have been measured in ballistic tests are much lower than the values that would be predicted on the basis of the indentation measurements. It is found that the penetration resistance depends on the fracture toughness, where the ratio of the measured target strength term to the hardness increases with the fracture toughness of the target.
[143] Steinhauser M O, Grass K.

2005. Failure and plasticity models of ceramics—A numerical study. The 11th Int Symposium on Plasticity and Current Applications, (PLASTICITY 2005), Kauai, Hawaii,

January 2005. 03-08.

[144] Strassburger E, Bauer S, Weber S, Gedon H.2016.

Flash X-ray cinematography analysis of dwell and penetration of small caliber projectiles with three types of SiC ceramics

. Defence Technology, 12: 277-283.

DOI      URL      [本文引用: 3]      摘要

In order to improve the performance of ceramic composite armor it is essential to know the mechanisms during each phase of the projectile–target interaction and their influence on the penetration resistance. Since the view on the crater zone and the tip of a projectile penetrating a ceramic is rapidly getting obscured by damaged material, a flash X-ray technique has to be applied in order to visualize projectile penetration. For this purpose, usually several flash X-ray tubes are arranged around the target and the radiographs are recorded on film. At EMI a flash X-ray imaging method has been developed, which provides up to eight flash radiographs in one experiment. A multi-anode 45065kV flash X-ray tube is utilized with this method. The radiation transmitted through the target is then detected on a fluorescent screen. The fluorescent screen converts the radiograph into an image in the visible wavelength range, which is photographed by means of a high-speed camera. This technique has been applied to visualize and analyze the penetration of 7.6265mm AP projectiles into three different types of SiC ceramics. Two commercial SiC grades and MICASIC (Metal Infiltrated Carbon derived SiC), a C-SiSiC ceramic developed by DLR, have been studied. The influences, not only of the ceramic but also the backing material, on dwell time and projectile erosion have been studied. Penetration curves have been determined and their relevance to the ballistic resistance is discussed.
[145] Subramanian R, Bless S J.1995.

Penetration of semi-infinite AD995 alumina targets by tungsten long rod penetrators

. International Journal of Impact Engineering, 17: 807-816.

DOI      URL      [本文引用: 1]      摘要

In tests in which the ratio of target diameter to penetrator diameter was reduced to 15, R t , dropped by 30% to 50%. When a steel coverplate was used, total interface defeat occurred at 1.5 km/s.
[146] Tate A.1967.

A theory for the deceleration of long rods after impact

. Journal of the Mechanics and Physics of Solids, 15: 387-399.

DOI      URL      [本文引用: 1]      摘要

A modified hydrodynamic theory which takes some account of strength effects is used to predict the deceleration of a long rod after striking a target. The results are then compared with experimental data from X-ray observations.
[147] Templeton D W, Holmquist T J, Leavy B.2002.

Computational simulations of interface defeat//The 2nd International Conference on Structural Stability and Dynamics Singapore

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[148] Thoma K, Helberg P, Strassburger E. Real2007.

Time-resolved flash X-ray numerical simulation validation cinematographic investigation of interface defeat and numerical simulation validation

//23rd International Symposium on Ballistics Tarragona, Spain, 2: 1065-1072.

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[149] Uth T, Deshpande V S.2013.

Unsteady penetration of a target by a liquid jet

. PNAS, 110: 20028-20033.

DOI      URL      PMID      [本文引用: 3]      摘要

http://www.pnas.org/cgi/doi/10.1073/pnas.1315130110
[150] Wadley H N, Børvik T, Olovsson L, Wetzel J J, Dharmasena K P, Hopperstad O S, et al.2013.

Deformation and fracture of impulsively loaded sandwich panels

. Journal of the Mechanics and Physics of Solids, 61: 674-699.

DOI      URL      [本文引用: 1]      摘要

Light metal sandwich panel structures with cellular cores have attracted interest for multifunctional applications which exploit their high bend strength and impact energy absorption. This concept has been explored here using a model 6061-T6 aluminum alloy system fabricated by friction stir weld joining extruded sandwich panels with a triangular corrugated core. Micro-hardness and miniature tensile coupon testing revealed that friction stir welding reduced the strength and ductility in the welds and a narrow heat affected zone on either side of the weld by approximately 30%. Square, edge clamped sandwich panels and solid plates of equal mass per unit area were subjected to localized impulsive loading by the impact of explosively accelerated, water saturated, sand shells. The hydrodynamic load and impulse applied by the sand were gradually increased by reducing the stand-off distance between the test charge and panel surfaces. The sandwich panels suffered global bending and stretching, and localized core crushing. As the pressure applied by the sand increased, face sheet fracture by a combination of tensile stretching and shear-off occurred first at the two clamped edges of the panels that were parallel with the corrugation and weld direction. The plane of these fractures always lay within the heat affected zone of the longitudinal welds. For the most intensively loaded panels additional cracks occurred at the other clamped boundaries and in the center of the panel. To investigate the dynamic deformation and fracture processes, a particle-based method has been used to simulate the impulsive loading of the panels. This has been combined with a finite element analysis utilizing a modified Johnson ook constitutive relation and a Cockcroft atham fracture criterion that accounted for local variation in material properties. The fully coupled simulation approach enabled the relationships between the soil-explosive test charge design, panel geometry, spatially varying material properties and the panel's deformation and dynamic failure responses to be explored. This comprehensive study reveals the existence of a strong instability in the loading that results from changes in sand particle reflection during dynamic evolution of the panel's surface topology. Significant fluid tructure interaction effects are also discovered at the sample sides and corners due to changes of the sand reflection angle by the edge clamping system.
[151] Walker J D, Anderson Jr C E.1991.

The Wilkins' computational ceramic model for CTH

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[152] Westerling L, Lundberg P, Lundberg B.2001.

Tungsten long-rod penetration into confined cylinders of boron carbide at and above ordnance velocities

. International Journal of Impact Engineering, 25: 703-714.

DOI      URL      [本文引用: 2]      摘要

The purpose was to investigate the influence of impact velocity and confinement on the resistance of boron carbide targets to the penetration of tungsten long-rod projectiles. Experimental tests with impact velocities from 1400 to 2600 m/s were performed using a two-stage light-gas gun and a reverse impact technique. The targets consisted of boron carbide cylinders confined by steel tubes of various thicknesses. Simulations were carried out using the AUTODYN-2D code and Johnson olmquist's constitutive model with and without damage evolution. The experimental results show that the penetration process had different character in three different regions. At low-impact velocities, no significant penetration occurred. At high-impact velocities, the relation between penetration velocity and impact velocity was approximately linear, and the penetration was steady and symmetrical. In between, there was a narrow transition region of impact velocities with intermittent and strongly variable penetration velocity. In the lower part of this region, extended lateral flow of the projectile took place on the surface of the target. The influence of confinement on penetration velocity was found to be small, especially at high-impact velocities. The simulated results for penetration velocity versus impact velocity agreed fairly well with the experimental results provided damage evolution was suspended below the transition region.
[153] Wilkins M L.1963.

Calculation of elastic-plastic flow

. DTIC Document.

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[154] Yuan J M, Tan G E, Goh W L.2016.

Simulation of dwell to penetration transion for SiC ceramics subjected to impact of tungsten long rods

. Advances in Ceramic Armor, Bioceramics, and Porous Materials: Ceramic Engineering and Science Proceedings, 37: 65.

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[155] Zavattieri P D.2000.

Ballistic penetration of multi-layered ceramic/steel targets

. AIP Conference Proceedings, 505: 1117-2220.

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[156] Zhang X F, Serjouei A, Sridhar I.2017.

Criterion for interface defeat to penetration transition of long rod projectile impact on ceramic armor

. Thin-Walled Structures.

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