Mode I and Mode II Interlaminar Fracture Toughness of Basalt/Kevlar Fiber Reinforced Epoxy Resin Hybrid Composites Incorporating Graphene Nanoplatelets

ABSTRACT This research examines the Mode I and Mode II fracture behavior of basalt/Kevlar fiber reinforced epoxy hybrid composites augmented with graphene nanoplatelets (GnP). Hybrid composites containing varying concentrations of GnP (0, 1, 2 and 3 wt%) were produced using vacuum‐assisted resin transfer molding. Mode I and Mode II fracture toughness was assessed using double cantilever beam and end‐notched flexure tests, performed in accordance with ASTM D5528 and ASTM D7905 standards, respectively. The addition of GnP markedly enhanced interlaminar fracture resistance, with the most pronounced improvements observed at GnP loadings of 1, 2 wt%. Specifically, Mode I fracture toughness increased by 51%, likely due to mechanisms such as crack deflection and bridging, whereas Mode II toughness increased by 6.2%, possibly due to improved fiber‐matrix interfacial bonding and redistribution of shear stresses. Scanning electron microscopy (SEM) analysis of the fracture surfaces revealed several toughening mechanisms, including GnP pull‐out, matrix plastic deformation and inhibition of fiber with matrix debonding. These results highlight the synergistic effects of GnP in basalt/Kevlar hybrid composites and suggest it is a viable strategy for engineering high‐performance materials with superior delamination resistance under opening and sharing loading modes. This research offers significant insights into the influence of nanofillers on the fracture behavior of hybrid composites and contributes to the development of advanced materials for engineering applications.