Abstract In previous experiments, the authors demonstrated that strain values collected from fiber Bragg gratings (FBG) integrated into a single layer of Kevlar fabric, placed between a soft armor test specimen and backing material, could be related to the time dependent back-face deformation (BFD) of the armor sample. In this paper, we investigate the specific fabric deformation and failure mechanisms that cause observed events in the FBG measured strain behavior and the FBG spectral profile throughout the impact event. For these experiments, the standard clay backing material was replaced with a 20% clear ballistic gel to provide visual access to the back-face. The test specimen was impacted by an 8.24 g steel ball bearing travelling at 248.8 m/s, during which strain was calculated from the measured full spectrum response of the FBG using a high-speed optical interrogation system. The strain response was compared to the BFD of the Kevlar sample. The BFD was measured through the clear ballistic gel using two high speed cameras recording at 100,000 fps. The results from these tests can be used for future testing using a non-transparent backing material to obtain a detailed strain–time history, back-face deformation history and an understanding of the time sequence of physical energy dissipation mechanisms in the fabric.

中文翻译：

---

使用光纤布拉格光栅在冲击过程中对防弹织物进行原位应变测量

摘要 在之前的实验中，作者证明了从集成到单层 Kevlar 织物中的光纤布拉格光栅 (FBG) 收集的应变值，放置在软装甲试样和背衬材料之间，可能与时间相关的背面变形有关。 (BFD) 装甲样本。在本文中，我们研究了在整个撞击事件中导致 FBG 测量应变行为和 FBG 光谱剖面中观察到的事件的特定织物变形和失效机制。对于这些实验，标准粘土背衬材料被 20% 透明防弹凝胶代替，以提供对背面的视觉访问。试样受到 8.24 g 钢球轴承的冲击，速度为 248.8 m/s，在此期间，使用高速光学询问系统从测量的 FBG 全光谱响应计算应变。将应变响应与 Kevlar 样品的 BFD 进行比较。使用两台以 100,000 fps 记录的高速摄像机通过透明弹道凝胶测量 BFD。这些测试的结果可用于未来使用非透明背衬材料进行的测试，以获得详细的应变时间历程、背面变形历史以及对织物中物理能量耗散机制的时间顺序的理解。