A thermal-mechanical constitutive model for b-HMX single crystal and cohesive interface under dynamic high pressure loading

Due to the significant thermal-mechanical effects during hot spot formation in PBX explosives, a thermodynamic constitutive model has been constructed for HMX anisotropic single crystal subjected to dynamic impact loading. The crystal plasticity model based on dislocation dynamics theory was employed to describe the anisotropic plastic behavior along the preferential slip systems. A modified equation of state (EOS) was introduced into the constitutive equations through the decomposing stress tensor and the nonlinear elasticity for materials was taken into account. The one-dimensional strain impact simulations for HMX single crystal and quasi-bicrystal were performed respectively, in which the cohesive elements were inserted over the interface areas for the latter. The predicted particle velocities for the single crystal sample agreed well with the experimental results in the literature. Furthermore, the effects of crystal orientations, interface, misorientations on localized strain, stress and temperature distributions were predicted and discussed.