Damage tolerance and assessment of foam-inflated aerospace structures

Design and operational issues with respect to the use of inflatable-deployable foam-rigidized components in aerospace structures are investigated in this paper. The sample structures used in this study are fabricated from flexible Kapton film formed into a cylindrical shell by bonding a flat sheet along a longitudinal seam. This tubular shell is injected with a hardening urethane foam to form a composite strut coupon. As with all structures touted for aerospace use, the survivability of foam-rigidized structures when subjected to a micrometeor flux is of interest. This issue is investigated in this paper by performing two controlled experiments: (1) Foam-rigidized test coupons were evaluated in their pristine state to determine structural properties, severely damaged in a controlled fashion, and then evaluated again to compare the undamaged to damaged behavior; and (2) a single specimen was repeatedly tested and then slightly damaged to examine how structural behavior evolves as damage accumulates. The results of these experiments are then used to draw conclusions about the utility of foam-rigidized structures in space applications, including an evaluation of appropriate structural health monitoring strategies.