Shear and flexural performance of CFRP single-lap joints bonded with graphene nanoparticle epoxy adhesive

Adhesive-bonded joints in carbon fiber-reinforced polymer composites offer several benefits, including enhanced flexibility, high specific strength, improved fatigue resistance, and reduced stress concentrations. Consequently, adhesive bonds are often considered more effective than mechanical fasteners. This study explores the impact of incorporating GNPs into the adhesive layer on the properties of secondary-bonded single-lap CFRP joints. These properties include shear and flexural strength, failure mechanisms, and fractography analysis. To improve interfacial strength, six GNP weight percentages 0.25, 0.50, 0.75, 1.0, 1.25, and 1.5 wt.% were tested. The results showed that incorporating 0.75 wt.% GNP increased shear strength by 26.87% compared with the plain adhesive, indicating improved load transfer between adherends. The flexural strength increased by 36.87% with 1 wt.% GNP. Microscopic examination of the fractured specimens revealed that the addition of GNPs roughened the surface, which enhanced the adhesion between the adhesive and adherends.