High-Speed Photomicrographic Recording Of Two-Dimensional Shock Wave Processes In Transparent Material

The primary emphasis of this paper is on the application of high speed photography to the study of small-scale, early time events associated with small particle impacts. The term high speed photomicrography has been used to emphasize the fact that magnifications greater than unity are employed in'order to make details of the material response accessible to experimental investigation. The unique combination of this approach and the recently-developed exploding wire particle launch technology, with its inherently high degree of aiming and timing accuracy, offers exciting new possibilities for advancing the state of understanding of the impact process. Photographs obtained on particle impact tests are presented, and their interpretation is discussed. Detailed analysis has been performed for the case of 1 mm diameter glass particles impacting at normal incidence on Plexiglas and fused silica. Various stages of shock wave generation and propagation, damage development and the formation and propagation of various types of fracture are identified. Some other important effects in particle impact are discussed briefly and illustrated by high speed photomicrographs and post-test photomicrographs.