Investigating multi-dimensional effects in single-crystal sapphire

Most studies in the past have focused on obtaining uni-axial strain states in shocked materials. In this study, however, results of symmetric impact gas gun experiments on single-crystal C-cut sapphire are described to observe edge relief waves as they propagate toward the center of the sapphire target shocked to high pressures. This is made possible by the recent development of a LINE ORVIS, which measures both spatial and time-resolved particle-velocity variations in materials. A series of experiments have been conducted over the impact velocity from ∼0.25 to 0.8 km/s, and in the elastic regime (except the 0.8km/s experiment). In these experiments, a new line imaging optically recording velocity interferometer system is used over a line segment of 13mm. Edge relief waves are unmistakably visible with local variations following the edge relief wave. Heterogeneous effects following dynamic yielding is also observed