Grain boundary effects on spall behavior of high purity copper cylinder under sweeping detonation

A series of sweeping detonation experiments were conducted to study the grain boundary effects during the primary spallation of high-purity copper cylinder. The free surface velocity profile of the shocked samples was measured by Doppler pins systems. The soft-recovered samples were characterized by optical and electron backscatter diffraction microscopy, and the effects of microstructures like grain boundaries, and crystal orientation on spall behavior were investigated. The results indicated that the critical stress of deformation twinning in cylindrical copper increased. The nucleation sites of spallation damage were determined by the joint influence of the grain orientation (Taylor factor) and the angle between grain boundaries and radial impact-stress direction. Voids were prone to nucleating at the grain boundaries perpendicular to the radial impact-stress direction. Nevertheless, the number of voids nucleated at boundaries was relatively different from the results obtained from the plate impact experiment and plate sweeping detonation experiment, which is a result of the curvature that existed in the cylindrical copper and the obliquity of the impact-stress direction during sweeping detonation loading.

Automated summary

A series of detonation experiments were conducted to study the grain boundary effects during the primary spallation of high-purity copper cylinder. The results indicated that the critical stress of deformation twinning in cylindrical copper increased, and the nucleation sites of spallation damage were influenced by both the grain orientation and the angle between grain boundaries and radial impact-stress direction.