A thermomechanical model for energetic materials with phase transformations

A model is developed to describe energetic materials with phase transformations from solid to liquid to gas with an exothermic chemical reaction. The model uses a phase variable and a reaction progress variable as thermodynamically independent state variables. A configurational force balance is used to derive an evolution law for the phase variable. The evolution equation for the reaction progress variable is posed as a basic law. In various limits the material is a classical elastic solid, a Newtonian viscous liquid, and a compressible gas. The model is examined in relation to classical equilibrium thermodynamics in a quasi-static limit. The model formulation is specialized to simple motions which are analyzed in a companion paper.