Testing of advanced materials for high resistance debris shielding

Abstract

Innovative 3-wall systems are developed to cope with the severe threat posed by on-orbit impacts of man-made debris. High resistance advanced shielding is based on an aluminum Whipple shield and an intermediate layer of advanced materials protecting an aluminum rear wall against hypervelocity impacts. Several intermediate bumpers have been tested as part of a hypervelocity test campaign using a Light Gas Gun firing aluminum spheres with a mass up to 6.1 g and a velocity up to 7 km/s. The use of low density, high strength cloth and composites (Kevlar™ and Kevlar™-Epoxy) greatly reduces the energy and the mass of the cloud hitting the rear wall. The introduction of ceramic fiber (Nextel™) is necessary to avoid a secondary effect (uprange blast) due to the rebound of projectile and intermediate bumper material against the external Whipple bumper, which causes large plastic deformations. The experiments showed excellent ballistic performance against aluminum projectiles at low velocity (3 km/s), high velocity (6–7 km/s), normal and 30-degree impacts. X-ray photographs are used to monitor the impact process, to study the debris cloud formation and evolution and to investigate the damage mechanism.