Coget Yann, Demarty Yaël, Rusinek Alexis
French-German research institute of Saint-Louis, 5 rue du Général Cassagnou, 68300 Saint-Louis, France.
Laboratory of Microstructure Studies and Mechanics of Materials, UMR-CNRS 7239, Lorraine University, 7 rue Félix Savart, BP 15082, 57073 Metz, France.
Materials (Basel). 2020 May 20;13(10):2357. doi: 10.3390/ma13102357.
The current needs in terms of ballistic protection for armed forces require an almost constant improvement in performance to face the constantly evolving threats and scenarios. Ballistic tests are conventionally carried out in order to assess and validate the levels of protection. The challenge is to be able to set up a digital protocol and only carry out final validation tests. Indeed, the advantage of digital simulation lies in the possibility of being able to evaluate a wide variety of configurations. In order to obtain reliable results, it is necessary to use sufficiently precise material behavior models to transcribe the phenomena observed during the impact. Our study focuses on the behavior of a small caliber ammunition with a ductile core impacting personal protection. More particularly on the mechanical behavior of the lead alloy core. Thus, compression tests have been carried out on a wide range of deformation rates, from quasi-static behavior to dynamic regime, at different temperatures. The study in dynamic conditions was carried out using split Hopkinson pressure bars. Due to the material properties, the experimental device had to be adapted in order to optimize the propagation of the waves allowing to measure signals (elastic waves). These tests demonstrate the dependency of the stress with strain rate and temperature. Dynamic restoration and recrystallization phenomena, characteristic of a material deformed in its hot working area, have also been identified. The associated oscillations due to Pochhammer-Chree effect, observable on the stress-strain curves, constitute the major problem for the implementation of behavioral models. Finally, a constitutive model sensitive to strain rate and temperature is investigated for ballistic purposes.
武装部队目前对防弹保护的需求要求在性能方面几乎持续改进，以应对不断演变的威胁和场景。传统上进行弹道测试是为了评估和验证防护水平。挑战在于能够建立一个数字协议，只进行最终验证测试。事实上，数字模拟的优势在于能够评估各种各样的配置。为了获得可靠的结果，有必要使用足够精确的材料行为模型来描述冲击过程中观察到的现象。我们的研究重点是具有韧性弹芯的小口径弹药对个人防护的作用。更具体地说是铅合金弹芯的力学行为。因此，已经在不同温度下，对从准静态行为到动态状态的广泛变形率进行了压缩试验。动态条件下的研究使用了分离式霍普金森压杆。由于材料特性，必须对实验装置进行调整，以优化允许测量信号（弹性波）的波的传播。这些测试证明了应力对应变率和温度的依赖性。还识别出了材料在其热加工区域变形时特有的动态回复和再结晶现象。在应力-应变曲线上可观察到的由于泊松-克里效应引起的相关振荡，是行为模型实施的主要问题。最后，研究了一种对应变率和温度敏感的本构模型用于弹道目的。
