The orientation dependence of
shock sensitivity in high
explosive crystals was explored in this study. As a widely used wood
explosive, 1,3,5-tri-amino-2,4,6-tri-nitrobenzene (TATB) is insensitive to thermal ignition and mechanical impact. Its typical anisotropic crystal structure suggests anisotropic
shock sensitivity. Shockwaves were applied to an incised TATB crystal along three orthogonal directions using the multiscale
shock technique (MSST) combined with the ReaxFF method to study the origin of anisotropic
shock sensitivity. The physical and chemical responses of the TATB crystal during
shock were investigated. The results show that the temperature, stress, volume compressibility, and decomposition rate of TATB are strongly dependent on the shockwave direction. In other words, the sensitivity of TATB to mechanical
shock is strongly dependent on the crystal orientation. TATB is relatively sensitive along the directions parallel to the (001) crystal plane (X and Y directions) and is highly insensitive along the [001] direction (Z direction). We calculated the energy of intermolecular hydrogen bonds and the elastic constants of the TATB crystal using ab initio simulations, which also show anisotropy. We found that the unique structure of intermolecular hydrogen bonds and the difference in temperature rise induced by orientation-related compressibility are primarily responsible for the anisotropic
shock wave sensitivity.