Impact response of carbon fiber/aluminum honeycomb sandwich structures under multiple low-velocity loads

The carbon fiber/aluminum honeycomb sandwich structures are susceptible to repeated impacts from external objects, which can significantly affect their performance and safety in engineering applications. Firstly, this study prepares two sandwich panels with different face/core interfaces: plain carbon fiber/aluminum honeycomb panels and Kevlar short-fiber-toughened interfaces and then discusses the effects of impact location and interface properties on the panels' multi-impact and post-impact compression performance, utilizing Digital Image Correlation (DIC) to elucidate the toughening effect of Kevlar short fibers. Lastly, the study examines the relationship between pit depth and residual compressive strength in both the Kevlar short-fiber-toughened and plain specimens. Experimental observations and theoretical analysis further explain the deeper deformation mechanism of sandwich specimens after impact. The mechanism reveals the main reason for the independent CAI strength of toughened specimens with pit depth. The results indicate that impact location and interface properties significantly affect the multi-impact and post-impact compression performance of the honeycomb sandwich panels. The correlation between the residual compressive strength of the Kevlar short-fiber-toughened specimens and the variations in impact position and pit depth is weaker. This distinct behavior from the plain specimens is attributed to the effective suppression of delamination damage caused by pit depth due to Kevlar short-fiber interface toughening, as well as the effective controlling of the impact damage zone by composite fillets.