Orientation-dependent Constitutive Model with Nonlinear Elasticity for Shocked β-HMX Single Crystal

Abstract

Abstract As orientation-dependence of shock-induced thermal responses and chemical reactions in energetic single crystals are related to anisotropic mechanical behavior, a crystal plasticity model for low-symmetric β-HMX single crystal with only limited operative slip systems has been developed. The model accounts for nonlinear elasticity, volumetric coupled with deviatoric behavior, and thermo-dynamical consistency. Simulations of planar impact on β-HMX single crystal show good agreement with existing particle velocity experimental data. An important feature of the model is its capability to capture the evolution of elastic-plastic wave profiles. The model provides new perspective to a range of complex, orientation-dependent mechanical and thermal behaviors than isotropic elastic-plastic constitutive descriptions. Pressure wave profiles show multiple fluctuations for single crystals with different orientations compared to that of isotropic medium. Simulated bulk temperature distribution and evolution with various characteristic features for different orientation single crystals are compared and discussed. Simulations for bicrystal samples show that the evolution and pattern of temperatures in different crystal pairs have great variations. Given that explosive grains are crystalline, the anisotropy of a crystal may be one of the sources of nonuniform temperature distribution.