Effect of internal stress fields on the perforation response of dual-wall structures under hypervelocity impact

Abstract

Traditional perforation-resistant wall design for long-duration spacecraft consists of a ‘bumper’ that is placed at a small distance away from the main ‘pressure wall’ of a spacecraft compartment or module. This concept has been studied extensively in the last four decades as a means of reducing the perforation threat of hypervelocity projectiles such as meteoroids and orbital debris. If a dual-wall systems is employed on an earth-orbiting spacecraft, then a biaxial stress field will be induced within the pressure wall of the dual-wall system due to the pressurization of the spacecraft. Unfortunately, little or no attempt has been made to include the effects of this low-level internal stress field in the study ofthe perforation resistance of dual-wall structural systems. This paper presents the results of an experimental study in which aluminum dual-wall structures were tested under a variety of high-speed impact conditions in an attempt to quantify the effect of an internal pressure wall stress field on perforation resistance. A test-by-test comparative analysis of the damage sustained by similar dual-wall systems with stressed and unstressed pressure wall plates under similar impact loading conditions revealed that the internal pressure wall stress field had a negligible effect on the ballistic limit of the dual-wall structures considered. However, the internal stress field did have a significant effect on the extent of the damage sustained by the pressure wall.