Molecular Simulations of Shock Interactions with Microstructural Defects in a Two-Component High Explosive System

Microstructural interfaces between energetic crystals and matrix materials (e.g., polymer binders) are thought to influence to the functional characteristics of high explosive (HE) formulations, but the material response at these interfaces can be difficult to access directly in experiments. To this end, we apply a recently developed all-atom molecular dynamics (MD) force field for a two-component molecular organic HE composite to investigate the role of microstructural surfaces and interfaces on hot spot formation during shock loading. By focusing on a system geometry designed to promote Richtmyer-Meshkov instabilities, we assess the role of shock strength and interfacial feature geometry on the resulting wave mechanics, material flow, phase mixing, and energy localization into hot spots. Scaling behavior with interface feature size is assessed. Implications for upscaling the physics of sub-micron-scale interfaces to improve the accuracy of coarse-grained continuum-mechanics models of HE formulations will be discussed.