Simulation of Void Collapse in an Energetic Material, Part I: Inert Case

An Eulerian, sharp-interface, fixed Cartesian grid method is applied to study hot-spot formation in an energetic material (HMX) subject to shock loading. The mass, momentum, and energy equations are solved along with evolution equations for deviatoric stresses and equivalent plastic strain. Pressure is obtained from the Mie-Griineisen equation of state. The material is modeled as a viscoplastic solid. High-order accurate essentially-nonoscillatory (ENO) shock-capturing schemes along with a particle-level set technique are used to evolve sharp immersed boundaries. The details of void collapse under shock loading and the resulting conversion of mechanical energy into localized regions of high thermal energy (hot spots) in the solid material are analyzed. Insights into the precise mechanisms of initiation sensitivity as a result of hot-spot formation in porous energetic materials are obtained.