Multi-scale modeling of shock initiation of a pressed energetic material. II. Effect of void-void interactions on energy localization

Abstract

Heterogeneous energetic materials (EMs) contain microstructural defects such as voids, cracks, interfaces, and delaminated zones. Under shock loading, these defects offer potential sites for energy localization, i.e., hotspot formation. In a porous EM, the collapse of one void can generate propagating blast waves and hotspots that can influence the hotspot phenomena at neighboring voids. Such void-void interactions must be accounted for in predictive multi-scale models for the reactive response of a porous EM. To infuse such meso-scale phenomena into a multi-scale framework, a meso-informed ignition and growth model (MES-IG) has been developed, where the influence of void-void interactions is incorporated into the overall reaction rate through a function, f v - v. Previously, MES-IG was applied to predict the sensitivity and reactive response of EM, where f v - v was assumed to be a function of the overall sample porosity alone. This paper performs a deeper analysis to model the strong dependency of f v - v on other factors, such as void size and shock strength. The improved model for void-void interactions produces good agreement with direct numerical simulations of the HE microstructures and, thus, advances the predictive capability of multi-scale models of the shock response and sensitivity of EM.