Interlaminar Shear Strength and Low‐Velocity Impact Tolerance of Carbon Fiber/Epoxy Laminates Enhanced by an Ultrathin Resin‐Infiltrated Porous Copper Framework

ABSTRACT Delamination and impact damage often initiate in the resin‐dominated interlaminar regions of carbon fiber‐reinforced polymer (CFRP) laminates. We designed a turtle‐carapace‐inspired architecture around an ultrathin, resin‐infiltrated porous copper framework. The framework was placed at the laminate mid‐plane, where epoxy infiltration formed an interpenetrating region through the thickness. Alkaline oxidative etching produced rough copper oxide/hydroxide micro/nanostructures on the copper ligaments, and aminosilane treatment was used to modify their interface with epoxy. Compared with the non‐interleaved CFRP laminate, the modified laminate showed a 19.4% higher mean interlaminar shear strength. Under low‐velocity impact, the mean peak force and final absorbed energy were 23.1% and 23.6% higher, respectively, whereas the mean maximum displacement was 9.5% lower. Mean compression‐after‐impact (CAI) strength was 23.5% higher. After specimen‐mass normalization, the mean CAI performance index was 115.5% ± 7.9% relative to Neat CFRP. Cross‐sectional and fracture observations indicate that epoxy penetrated the porous framework and interlocked with it through the thickness; the modified ligament surfaces also retained more resin after fracture. After accounting for the added interleaf mass, the laminate retained its gains in interlaminar shear strength and impact damage tolerance without any decrease in measured compressive or flexural performance, indicating a weight‐efficient interlaminar reinforcement route.