When a shock wave reflects at the interface between the surface of a metal presenting geometrical defects and air, the defects invert and form thin jets. These jets expand ahead of the main metal surface, and the high strain rate they undergo leads to their breaking into a great amount of small particles. This phenomenon is known as microjetting. The physic of the shock and release governing this jet’s formation is complex and not fully understood. We recently show that a previously known but not understood effect, the increased in density at the edge of ejecta clouds is due to the coalescence of the edge jets with their closest neighbor. In this study, we show that the coalescence comes from the destabilization during the formation the edge jets by release waves. Indeed, varying the gap between defects and the shock wave pressure, we show the evolution of the edge jets, from unperturbed to highly destabilized. For this study, jet generation was obtained through the impact on the Sn sample of a highspeed copper projectile launched with a gas gun. Several groove geometries (chevron, fly-cut and square profiles) have been studied, and microjets’ evolution was imaged with high speed X-ray radiography
2025-04-09 09:00:00
