Hypervelocity impact on Whipple shields with varying bumper material at 3 and 7 km/s: An experimental study

Abstract

The behavior of various bumper materials subjected to hypervelocity impact is of high interest, as different materials show varying ability to shock and break up an incoming projectile, and can produce varying amounts of ejecta on impact. In this study, an experimental campaign of 10 normal impacts of spherical Al 2017-T4 projectiles on Whipple shields at 3 and 7 km/s is presented, with various bumper configurations of near equal areal density. Five different bumper configurations are studied (aluminum wire mesh, steel wire mesh, Nextel woven fabric, open-cell aluminum foam with a face sheet, and Beta cloth with an aluminum plate) and compared to a traditional thin Al 6061-T6 bumper. The results are evaluated based on high-speed video footage of the debris cloud development over the standoff distance, as well as observed damage on the ejecta catcher, bumper, rear wall, and witness plate, and 3D scans of the rear walls and witness plates. The results are found to be significantly different between the different bumper configurations. At 3 km/s, the bumper configuration with open-cell aluminum foam with a face sheet performed best, while at 7 km/s, the baseline Al 6061-T6 bumper and the bumper with Beta cloth showed the best performance.