Hypervelocity Impact Testing of Multiwall Targets Using Multiple Simultaneously Launched Projectiles

Abstract

Multiwall shield designs for spacecraft have been studied extensively in the last four decades as a means of reducing the perforation threat of the near-Earth particulate environment over equivalent single-wall structures. The performance of an impact shield is typically characterized by its ballistic limit equation, which is obtained through high-speed impact tests that typically use spherical projectiles fired in light gas guns. Traditional firings employ only one projectile per launch package. However, some facilities have taken to launching multiple projectiles of different sizes in a single launch package. In light of the significant role played by a ballistic limit equation in risk assessment, a study was performed to examine whether or not this method of simultaneously launching several projectiles at a single target could give rise to some issues which may compromise the impact test data obtained in this manner. It was found that interference between debris clouds created by the impacting (simultaneously launched) particles could indeed occur. This in turn could affect the damage levels caused by the impacting particles as compared to those that would be seen in more standard single-projectile impact tests under the same impact conditions.