Metallographic Investigation of Structural Changes upon Collapse of Cylindrical Copper Shells

Abstract

Metallography has been used in this study to investigate copper samples cut from cylindrical shells collapsed under shock wave loading. Spallation phenomena (either the shell is divided into concentric rings, or a wide zone with spallation cavities and cracks is formed), which occur in shells under shock wave loading are considered. High-rate deformation during inertial convergence heals pores and cracks. Traces of healing remain in the microstructure. Various cases of nonradial convergence, when a stable circular deformation front is lost, are observed. Bends appear on the thin-walled shell and the shell crumples during its converging. Periodically arranged protrusions form on the inner surface of the thick-walled shells. They subsequently join together, converging to the center of the shell. A wave-shaped relief, protrusions, dents, and corrugation on the outer surface indicate the loss of stability.