Rice-Walsh equation of state for unreacted high explosives based on isothermal compression data

Equation of state (EOS) for unreacted explosives, PETN has been formulated thermodynamically aiming at using with numerical code of shock to detonation transition processes. In this paper, a generalized procedure of providing {\em pressure-volume-enthalpy} EOS is proposed based on the available static isothermal high-pressure compression curve. The present procedure can be used to formulate the Rice-Walsh type EOS by using the specific heat at constant pressure as a function of entropy, {\em C$_p$}({\em S}), and pressure-dependent Wu-Jing parameter with the material parameter $\beta$ introduced by the author. Birch-Murnaghan functional form is adopted as an isothermal compression curve. Specific heat function was derived from the measured temperature dependence at atmospheric pressure. In order to estimate the parameter $\beta$ in the Wu-Jing parameter, shock Hugoniot curve for PETN were calculated varying the value, $\beta$ as a parameter. Both values of $\beta$ determined to reproduce the shock Hugoniot for TMD and porous samples were found to be very similar and were very small compared with those estimated for various metals.