Wen Yaoke, Xu Cheng, Wang Shu, Batra R C
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
J Mech Behav Biomed Mater. 2015 May;45:11-21. doi: 10.1016/j.jmbbm.2015.01.010. Epub 2015 Jan 21.
The impact response of body armor composed of a ceramic plate with an ultrahigh molecular weight polyethylene (UHMWPE) fiber-reinforced composite and layers of UHMWPE fibers shielding a block of ballistic gelatin has been experimentally and numerically analyzed. It is a surrogate model for studying injuries to human torso caused by a bullet striking body protection armor placed on a person. Photographs taken with a high speed camera are used to determine deformations of the armor and the gelatin. The maximum depth of the temporary cavity formed in the ballistic gelatin and the peak pressure 40mm behind the center of the gelatin front face contacting the armor are found to be, respectively, ~34mm and ~15MPa. The Johnson-Holmquist material model has been used to simulate deformations and failure of the ceramic. The UHMWPE fiber-reinforced composite and the UHMWPE fiber layers are modeled as linear elastic orthotropic materials. The gelatin is modeled as a strain-rate dependent hyperelastic material. Values of material parameters are taken from the open literature. The computed evolution of the temporary cavity formed in the gelatin is found to qualitatively agree with that seen in experiments. Furthermore, the computed time histories of the average pressure at four points in the gelatin agree with the corresponding experimentally measured ones. The maximum pressure at a point and the depth of the temporary cavity formed in the gelatin can be taken as measures of the severity of the bodily injury caused by the impact; e.g. see the United States National Institute of Justice standard 0101.06-Ballistic Resistance of Body Armor.
对由超高分子量聚乙烯（UHMWPE）纤维增强复合材料制成的陶瓷板以及多层UHMWPE纤维组成的防弹衣进行了实验和数值分析，该防弹衣用于防护一块防弹明胶。它是研究子弹击中人体上所穿防弹衣时对人体躯干造成伤害的替代模型。利用高速摄像机拍摄的照片来确定防弹衣和明胶的变形情况。发现在防弹明胶中形成的临时空腔的最大深度以及在明胶前表面与防弹衣接触中心后方40毫米处的峰值压力分别约为34毫米和约15兆帕。采用约翰逊 - 霍尔姆奎斯特材料模型来模拟陶瓷的变形和失效。将UHMWPE纤维增强复合材料和UHMWPE纤维层建模为线性弹性正交各向异性材料。将明胶建模为应变率相关的超弹性材料。材料参数值取自公开文献。发现计算得到的明胶中临时空腔的演变在定性上与实验中观察到的一致。此外，计算得到的明胶中四个点处的平均压力随时间变化的曲线与相应的实验测量结果相符。明胶中某一点的最大压力和形成的临时空腔深度可作为撞击对身体造成伤害严重程度的度量；例如参见美国国家司法研究所标准0101.06 - 防弹衣的防弹性能。
