Energy storage and dissipation of elastic-plastic deformation under shock compression: Simulation and Analysis

Abstract

Stored energy plays a crucial role in dynamic recovery, recrystallization, and formation of adiabatic shear bands in metals and alloys. Here, we systematically investigate the energy storage and heat dissipation in copper single crystals with two typical orientations under shock compression and reveal their microscopic mechanisms using molecular dynamics simulations. Based on the theoretical framework of decoupling elastic-plastic deformation, the deformation is explicitly decomposed into elastic and plastic parts at the atomic scale. Temperature changes induced by thermoelastic coupling and heat dissipation of plastic work are also theoretically derived from the viewpoint of energy conservation. Through analyzing the relationship between the elastic strain, plastic work, and temperature rise, the ratio of energy storage to heat dissipation under shock compression are well identified and comprehensively discussed. The results show that the effect of the strain rate on energy storage and dissipation significantly depends on the crystallographic orientation, such that, for [001] copper, the ratio of energy storage to heat dissipation does not vary appreciably with the strain rate. In contrast, for [123] copper, plastic work with a high strain rate (such as shock compression) is likely stored in the form of dislocations compared with that at a low strain rate where heat dissipation is dominant.