Hyper-Velocity Impact Performance of Foldcore Sandwich Composites

Abstract

A foldcore is a novel core made from a flat sheet of any material folded into a desired pattern. A foldcore sandwich composite (FSC) provides highly tailorable structural performance over conventional sandwich composites made with honeycomb or synthetic polymer foam cores. Foldcore design can be optimized to accommodate complex shapes and unit cell geometries suitable for protective shielding structures This work aims to characterize hypervelocity impact (> 2000 m/s, HVI) response and corresponding damage morphologies of carbon fiber reinforced polymer (CFRP) FSCs. A series of normal (0° impact angle) and oblique (45° impact angle) HVI (~3km/s nominal projectile velocity) impact tests were performed on CFRP FSC targets to understand the effects of projectile impact on redirected debris formation, and variable debris cloud expansion. HVI damage in FSC targets were assessed using visual inspection and high-speed imaging analysis. The results from the present study indicate that debris cloud propagation and expansion are strongly influenced by foldcore impact location/angle and open-channel direction. This work serves as a baseline study to understand HVI response of FSC targets and to identify critical FSC design parameters to optimize HVI mitigation performance.