含缺陷分布的 β-HMX 单晶动态拉伸变形及破坏机理

The deformation, damage and failure process of β-HMX single crystal with different defect characteristics (porosity, void number and void distribution morphology) under dynamic tension are simulated by molecular dynamics method based on Smith force field. The influence of internal defects in β-HMX single crystal on its mechanical behavior is studied through simulation. The results show that, when the porosity increases from 1% to 2%, the tensile strength of β-HMX single crystal is decreased by 5. 3% - 11. 2% compared with the perfect single crystal, and the Young's modulus is decreased by 3. 6% - 13. 4% . When the porosity is constant, the tensile strength of the crystal decreases with the increase in the nuer of void. When the distance between the voids is small, the interaction between the voids is presented during the tensile process, resulting in the decrease of the tensile strength. The distribution of voids has a significant effect on the tensile strength of β-HMX single crystal. The failure mechanism of β-HMX single crystal under different strain rates is obviously different. Small cracks are formed around the voids at the tensile strain rate of 5 × 10⁹ s ^{- 1} , and the cracks gradually expand, which leads to the fracture of β-HMX single crystal. The material has obvious fracture. Multiple cracks were formed inside the β-HMX single crystal under the tensile strain rate of 1 × 10¹¹ s ^{- 1} , resulting in the failure of the material. The dynamic tensile deformation and failure mechanism of β-HMX single crystal with defect distribution are obtained, which provides a theoretical basis for optimizing the preparation process of β-HMX and its mixed explosives and improving their mechanical properties.