Equation of state for energetic structural materials

Current investigations of energetic structural materials involve shock-induced and shock-assisted chemical reactions in which complex physical processes are currently only elucidated by computational models of gas-gun experiments. The equation of state is one of the most important parts of the constitutive models incorporated into models that describe the processes in shock-induced and shock-assisted chemical reactions. Implementation of current methods typically requires simplifying assumptions in the mixture rules. In this paper, two new equation-of-state methods are proposed that 1) are used to physically interpret both homobaric and uniform-strain assumptions, 2) do not require mixture-averaged equation-of-state model parameters, and 3) do not have any restrictions on the form of constituent equation-of-state or pore-collapse model. The proposed methods are compared with other mixture equation-of-state methods, and cases in which the mixture is porous are demonstrated. Gas-gun experiments are simulated and compared with experimental data for a material with 2Al, [Fe.sub.2][O.sub.3], 20 wt % Epon 828, and voids, in which the reaction initiation threshold was not reached. The simulation integrates conservation equations and momentum balance using a second-order finite volume scheme. DOI: 10.2514/1.34472