Effect of core hybridization on composite sandwich panels’ low-velocity impact and bending response

This study examines the mechanical response of multi-layered sandwich panels comprising glass fiber-reinforced polymer (GFRP) face sheets and hybrid cores made of aluminum honeycomb and modified sinusoidal corrugated layers, bonded using aerospace-grade adhesives. Experimental investigations were conducted under three-point bending (3PB) and local impact indentation tests using a universal and a drop weight impact testing machine. The load-displacement responses were recorded for all specimens, and the damage mechanisms are highlighted. Four core configurations were fabricated based on different layering sequences, and their peak load and specific energy absorption capacities were evaluated. Results show that integrating corrugated layers with honeycomb cores generally enhanced the deformation capacity, enabling panels to sustain loading over larger displacements. Progressive and steady crushing in various hybrid configurations improved load capacity and specific energy dissipation; but, localized debonding and interface instabilities continue to pose significant challenges for long-term durability. In comparison to the all-honeycomb baseline (HHH), the inclusion of a single corrugated layer HCH drop of peak load by 30% and improved specific energy absorption by 50%. Dual-corrugated topologies (HCC/CCH) drop peak load by 41%–58%, while symmetric designs such as CHC(S) and CCH(S) showed the biggest benefits, with 17%–41% lower peak loads. Symmetric stacks displayed the most consistent multi-peak crushing response. These findings underline the possibility of tailored hybrid core architectures in increasing specific energy dissipation and structural performance in lightweight engineering applications.