Supersonic Impact Response of Polymer Thin Films via Large-Scale Atomistic Simulations

Abstract

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 (E p *) versus impact velocity predicts to within 15% the experimentally determined E p * for PS. For impact velocities less than 1 km s −1 , 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 −1 . 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.

High Strain Rate Failure Behavior of Polycarbonate Plates due to Hypervelocity Impact

“…Future experiments will focus on recovering the BFDC material for investigating the possible decomposition including carbonization and sublimation of polymers. Recent simulations showed that high v 0 on polystyrene targets would result in significant molecular chain decomposition …”

“…Response of polymeric materials in the ballistic range, ≳500 m/s, has been reported in the literature. , Particularly, recent reports focus on the polymer thin films’ response captured using laser-induced impact testing (LIPIT). LIPIT experiments involve microprojectile impact on polymer films with a thickness of a few hundred nanometers at impact velocity (v 0 ) as high as 1,000 m/s. ,− The estimated strain rate in these experiments is ∼10 7 –10 8 s –1 . Although the projectile velocity in these experiments is lower than hypervelocity, a very high strain rate is achieved because of very thin targets.…”

Mechanical and thermal properties of carbon nanotubes in carbon nanotube fibers under tension–torsion loading

“…44 Recently, it has been demonstrated that, when trained using machine learning, GAP could simulate the thermal and mechanical properties of pristine and defective carbon. 42,45 Especially, AIREBO has been widely used to study the thermal and mechanical properties of carbon-based materials, [46][47][48][49][50][51] and the obtained results are reasonable and widely acknowledged. Furthermore, it is wellknown that, in molecular dynamics simulations, the simulated results obtained using different potentials are slightly different.…”

Multiple Impact-Resistant 2D Covalent Organic Framework

“…However, the cracks near the impact location are easy to propagate, which could lead to rapidly structure failure. In contrast, the 2D ultrathin polymer-based film not only exhibits high specific penetration energy due to their size-dependent energy dissipation mechanisms − but also can restrain crack propagation. Besides, the porous woven and nonwoven carbon nanotube-based 2D textiles also display remarkable crack-insensitive properties under high-velocity impact. − Then, an interesting topic is that how about the impact-resistant mechanical behaviors of polymer-based porous COF?…”