Energy absorption mechanisms of nanoscopic multilayer structures under ballistic impact loading

MAN Dewapriya and RE Miller, COMPUTATIONAL MATERIALS SCIENCE, 195, 110504 (2021).

DOI: 10.1016/j.commatsci.2021.110504

We conducted large-scale molecular dynamics (MD) simulations of ballistic impact tests on ultrathin aluminum and polyurea layers and their multilayer arrangements to investigate the energy absorption and deformation mechanisms at the nanoscale. In contrast to the results obtained from experiments conducted at the macroscale, our nanoscale simulations demonstrate that a polymer layer on the strike face is more effective in mitigating impact-induced damage. A polymer layer on the back face is weakened by the shock wave reverberation. The temporal variations of shock pressure and temperature, due to adiabatic heating of the targets, were analyzed to understand the energy dissipation mechanisms under supersonic projectile impacts. The shock pressure and adiabatic heating of polymer films significantly increase as the film thickness decreases. During the perforation, a nanoscopic projectile experiences two substantially different levels of resistance due to the interaction between the incident projectile and the tensile release wave. Moreover, the vertical surface area of a nanoscale projectile contributes significantly to the absorption of impact energy during the perforation.

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