Carbon/epoxy composite shielding system and effect of stuffing fabric on system performance

Abstract

In this paper, carbon/epoxy composite materials in combination with stuffing fabrics were experimentally examined by utilizing a unique configuration of intermediate bumpers to encounter impact events and protect the remaining structure from such impact events. Carbon/epoxy composites [0/+/- 45/90](2s) were manufactured, exposed to LEO environment, stacked and arranged in a special geometric configuration. The incorporation of Nextel AF62 and Kevlar KM2 was also carried out in the final shielding configuration. Afterward, samples were impacted using an Al2017-T4 spherical projectile that was 5.56 mm in diameter and 0.25 g in weight, in a velocity range of 2000 +/- 500 m/s, with the help of a two stage light gas gun. The triple bumpers, which had oblique intermediate bumpers, absorbed more energy with the increase of the obliquity of the intermediate bumper. Inclination increase from 30 degrees to 45 degrees led to an increase of 30% of the specific energy absorption. The insertion of stuffing fabric enabled this shielding system to absorb all the energy carried by the projectiles, showing no damage to further components. CSCAN images were also used to determine the damage profile and extent of delamination in the specimens after the impact events. This shielding concept of utilizing composites with stuffing fabrics, along with an inclination of the intermediate bumper, can effectively protect the structure while maintaining the same volume according to different threat levels. Greater levels of threat can be easily handled with more obliquity.