Effect of crystal orientation on shock initiation sensitivity of pentaerythritol tetranitrate explosive

Pentaerythritol tetranitrate single crystals were shocked in four different orientations with the shock direction parallel to the 〈110〉, 〈001〉, 〈101〉, or 〈100〉 crystallographic directions. Input stresses were 8.6 or 12.4 GPa. At 12.4 GPa detonation occurred in less than 10-mm run distance of the shock for the 〈110〉 and 〈001〉 orientations. For the 〈101〉 and 〈100〉 orientations, denotation was not observed. There is a difference of more than a factor of 2 in run distance to detonation with crystal orientation. The effect can be understood in terms of the available slip systems in the uniaxial strain associated with plane shock compression. In addition, an intermediate velocity transition was observed at 8.6-GPa shock stress for 〈101〉 orientation.