Abstract
Equation of state (EOS) for unreacted high explosives, PETN and HMX has been formulated thermodynamically aiming at using it in numerical code of shock to detonation transition processes. In this paper, a generalized procedure of providing the Rice-Walsh type EOS, i.e., pressure-volume-enthalpy EOS is proposed based on the available static isothermal compression curve. The present method can be used to describe the EOS for unreacted high explosives by
using the specific heat at constant pressure as a function of entropy, Cp(S), and the pressure-dependent Wu-Jing parameter with the material parameter β introduced previously by the author.
Birch-Murnaghan functional form is adopted as an isothermal compression curve. Specific heat function Cp(S) was derived from the measured temperature dependence of specific heat at atmospheric pressure. In order to estimate the parameter β in the Wu-Jing parameter, shock Hugoniot curve for PETN and HMX were calculated by varying the value, β as a parameter. Values of β for both PETN and HMX were determined to reproduce the available shock Hugoniot data for TMD and porous samples of these two explosives and were found to be very similar for both explosives and were very small compared with those estimated previously for various metals.
By using the established EOS for high explosives, shock Hugoniot Us-Up for both TMD and porous samples were calculated and shown. Calculated shock Hugoniot curves are in good agreement with the available dynamic data.
