Effect of B4C Particulates Addition on the Hardness of Polymeric Resins and Mode-I Interlaminar Fracture Toughness of Carbon/Epoxy Textile Composite

This research explores the combined effect of hardness and stiffness on the Mode-I interlaminar fracture toughness (ILFT) of carbon fabric-reinforced polymer (CFRP) composite laminate using a double cantilever beam (DCB) test specimen. The micro-sized hard ceramic boron carbide (B4C) particulates were reinforced with carbon fabric (high stiffness) in epoxy resin for the ILFT study. The B4C particulates were considered in 1000, 1500, and 2000 mesh sizes and 1%, 3%, 5%, 7%, and 9% weight distribution for hardness study. The quality of particulates was ensured using scanning electron microscope (SEM) and x-ray diffraction (XRD) analyses. A suitable combination of mesh size and weight distribution was obtained using the hardness study of B4C-reinforced epoxy and vinylester composites, and B4C with plain and twill woven carbon fabric-reinforced epoxy and vinylester composites. The 2000 mesh size B4C particulates at 3% weight distribution and plain woven carbon fabric-reinforced epoxy composite exhibited the highest hardness value. This configuration was selected for the Mode-I ILFT study. The composite panel was fabricated using a hand layup process followed by the vacuum-assisted resin transfer molding (VARTM) technique. The B4C-reinforced CFRP composite exhibited 56.15% higher ILFT than the B4C-unfilled CFRP composite. The B4C particulates significantly increase the Mode-I ILFT of CFRP composite, however after reaching the peak load, unstable crack propagation, rapid crack jumps, and sudden load drops were observed in the DCB specimens due to the brittle nature of carbon fiber and sharp edges of B4C particulates.