Understanding the spall behaviors of single crystalline aluminum under double decaying shock loadings: Atomistic simulations and theoretical models

Abstract

The shock responses of single crystalline aluminum under double decaying shock loadings are systematically studied by atomistic simulations and theoretical models. Two successive spall events in the same region are observed, which were controlled by voids formation-collapse-formation mechanism. The spall strength for the second spallation was significantly reduced and gradually decreased with increasing time interval. The important dynamic properties, such as spall strength and void nucleation threshold, are significantly different and depend on microstructure and temperature. Furthermore, an analytical expression has been developed to quantify the temperature effect on the nucleation threshold for the second spallation. The damage evolution of two successive spall events in the same region is described by a combination of a nucleation threshold model and a nucleation-and-growth model complemented with the voids collapse process. The voids volume fractions from theoretical models and simulations show good agreement, demonstrating that the theoretical models are feasible for describing the nucleation threshold variation and damage evolution under double decaying shock loadings. The spall behaviors and theoretical models provide insights into further understanding the dynamic responses under complex shock loadings.