HOT-SPOT IGNITION OF CONDENSED-PHASE ENERGETIC MATERIALS

A micromechanics approach to hot-spot:formation and growth to detonati on in condensed-phase energetic materials is presented. A numerical mo del based on fundamental conservation principles is developed to exami ne the dynamic and thermodynamic processes that occur in a generalized heterogeneous, energetic material subjected to weak shock loading. Th e work focuses on the thermal/mechanical processes that act to transfe r compression work of the shock wave into localized high-temperature i gnition sites, ii special interest of this research is to determine th e dominant physical processes occurring at different times during hot spot formation, Processes such as viscoplastic heating, phase change, finite rate condensed-phase decomposition, gas-phase heating, and heat transfer between the void and the condensed-phase are included in the model. Results for cyclotrimethylene trinitramine (C3H6N6O6), a commo n ingredient in high-energy solid rocket propellants, show that viscop lastic heating is an effective mechanism for producing high-temperatur e regions in the energetic material adjacent to a shock-collapsed void . Furthermore, it is shown that under certain initial conditions (pore size, shock pressure, etc,), localized heating can lead to the releas e of chemical energy that exceeds the energy dissipated by heat losses , and that melting and the variation of condensed-phase viscosity and yield strength can greatly affect the dynamics of pore collapse.