Engineer Research and Development Center, 3909 Halls Ferry Rd., Vicksburg, Mississippi 39180, United States of America.
Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States of America.
Nano Lett. 2021 Jul 28;21(14):5991-5997. doi: 10.1021/acs.nanolett.1c00961. Epub 2021 Jul 15.
Recent nanoscale ballistic tests have shown the applicability of nanomaterials for ballistic protection but have raised questions regarding the nanoscale structure-property relationships that contribute to the ballistic response. Herein, we report on multimillion-atom reactive molecular dynamics simulations of the supersonic impact, penetration, and failure of polyethylene (PE) and polystyrene (PS) ultrathin films. The simulated specific penetration energy (*) versus impact velocity predicts to within 15% the experimentally determined * for PS. For impact velocities less than 1 km s, a crazing/petalling failure mode is observed due to chain disentanglement, transitioning to fragmentation coupled with large amounts of adiabatic heating at velocities greater than 1 km s. Interestingly, the high entanglement density of PE provides enhanced penetration resistance at low velocities, whereas increased adiabatic heating in PS promotes greater penetration resistance at elevated velocities. By understanding nanoscale mechanisms of energy absorption, nanomaterials can be designed to provide superior penetration resistance.
最近的纳米级弹道测试表明了纳米材料在弹道保护方面的适用性，但也提出了一些问题，即纳米级结构-性能关系对弹道响应的贡献。在此，我们报告了关于聚乙烯（PE）和聚苯乙烯（PS）超薄薄膜的超音速冲击、穿透和失效的数百万原子反应分子动力学模拟。模拟的比能穿透（）与冲击速度的关系在 15%的范围内预测了 PS 的实验确定的。对于低于 1 km/s 的冲击速度，由于链解缠，观察到了发粘/花瓣状失效模式，在速度大于 1 km/s 时，会过渡到碎片与大量绝热加热相结合。有趣的是，PE 的高缠结密度在低速时提供了增强的穿透阻力，而 PS 中的绝热加热增加在高速时促进了更大的穿透阻力。通过了解能量吸收的纳米级机制，可以设计纳米材料以提供卓越的穿透阻力。
