高温下奥克托今单晶冲击响应数值计算

A nonlinear thermoelastic-viscoplastic model is developed for studying the thermodynamic response of octogen (HMX) single crystal at elevated temperatures, in which the thermal activation and phonon drag dislocation glide regime are considered. The proposed model can reproduce the thermal hardening behavior of Hugoniot elastic limit (HEL) of HMX single crystal in plate impact experiment. The effects of phonon scattering and radiation damping on the thermal hardening behavior are quantitatively analyzed to investigate the evolution of dislocation glide regime and the thermodynamic response at 373 K and 423 K. It is found that the thermal hardening behavior of HEL of HMX single crystal is due to the increase in phonon scattering and radiation damping with the initial temperature from 300 K to 423 K. The phonon drag coefficient is increased to strengthen the viscous friction of mobile dislocation. Therefore, the average dislocation velocity decreases from 2 237 m/s to 1 537m/s, which leads to slower plastic shear strain rate and higher flow stress. The shear modulus changes slightly with the increase in temperature (about 1.0 GPa), thus the contribution of radiation damping to thermal hardening is less than that of phonon scattering.