Investigation of the out of plane response of multi-layer corrugated composite structures under low-velocity impact loading: Experimental analysis

This study aims to investigate the influence of integrated multilayer configurations and innovative corrugated core geometries (butterfly and square) on the low-velocity impact performance of composite sandwich panels. The panels, including skins and cores, were fabricated from woven glass fiber and ML-506 epoxy resin with HA-11 hardener using the Vacuum-Assisted Resin Transfer Molding (VARTM) technique. Low-velocity impact tests were conducted using hemispherical cylindrical indenters with diameters of 10 mm and 20 mm to examine the effect of impactor size on structural response. Key parameters analyzed included contact force, total and specific energy absorption, global bending deformation, and fracture patterns, for both foam-filled and non-foam-filled panels. The results indicate that, without foam, butterfly-shaped cores achieved higher peak load (up to 1239.5 N), greater energy absorption (up to 13.429 J) and specific energy absorption (up to 0.417 J/g), and failure displacement compared to square cores. Additionally, the 10 mm indenter primarily caused perforation, whereas the 20 mm indenter induced crushing failure. These findings highlight the critical role of core geometry and impactor size in determining the impact resistance and energy absorption efficiency of multilayer composite sandwich panels.