Microstructure-informed, statistical approach for shock to detonation transition modelling in high explosives

Shock to detonation transition phenomenon (STDT) is a synergistic effect of different underlying mechanical, chemical, and thermal processes, where the racing between different modes of energy production and dissipation is the key factor. Accurate prediction of these far-from-thermodynamic-equilibrium phenomena dictates careful consideration of different entropic fluxes associated with various inelastic processes, along with their characteristic modes of transport. Hot-spot formation and initiation is the main paradigm to tackle STDT, which, in turn, is known to be heterogeneous in nature. Accordingly, mean-field approaches, which employ averaged-measures of microstructural properties, predict critical parameters for STDT regime that can deviate significantly from experiment. In the present study, we seek a statistical approach to represent the heterogeneity in the microstructure of polymer-bonded explosives, which better captures the sensitivity of hot-spot initiation to local variation in the microstructure. The reactive flow system of equations is solved in Lagrangian framework, within finite strain formalism. In addition, this thermo-mechanical-chemical model is supplemented by the Hugoniot equation of state for closure purposes and solved using finite-element technique.