Evaluation of the roles of crystal plasticity and hydrodynamic jetting in hot-spot formation in heterogeneous energetic materials under shocks

Heterogeneous energetic materials are crucial components in munitions and energy-delivery systems. Under shocks, localized hot-spots are formed near voids and microstructural defects in these materials. Hydrodynamic jetting due to void collapse and strain localization due to plastic work are two important mechanisms for hot-spot formation in the material. This work evaluates the relative contribution of these two mechanisms in the formation of hot-spots under shocks in energetic materials. To this end, an Eulerian computational framework is used to study the response of HMXs comprising a single void under shock loading. To study the role of hydrodynamic jetting, the voids are resolved sharply using level-sets and the hot-spot temperatures are tracked at different stages of void collapse. To model heating due to plastic work, an anisotropic crystal plasticity model based on a power-law slip-rate with hardening and thermal softening is used; the localized temperatures in the slip/shear bands formed in the material under shocks are also tracked. Computations are performed for different crystal orientations and shock strength. The presentation will discuss the combined roles of jetting and plastic heating in hot-spot formation in HMXs.