An improved temperature-dependent specific heat model for unreacted explosive equations of state

Abstract

The any Mie-Grüneisen Equation of State (AMEOS) model in CTH, a shock was calibrated for four unreacted homogeneous explosives in temperature-volume space: HMX, TATB, PETN, and RDX. AMEOS employs a multi-term Einstein oscillator function, which is used to fit the specific heat over a range of temperature values. Here, this model is used to calculate a family of Hugoniot temperature curves that are much lower than for a constant specific heat approximation. Moreover, there is limited thermal EOS data which is extrapolated to the classic Dulong-Petit limit. Mesoscale simulations with Arrhenius burn models require this type of thermodynamically complete EOS for accurate temperature-based reaction rates. The improvements with temperature dependent versus constant specific heat are discussed, in addition to the Einstein oscillator coefficient fits for the four different homogeneous explosives considered.