Investigation of the effect of nanoparticles on adhesion of single lap joints in composites

Adhesively bonded joints of fiber-reinforced polymer structural components offer numerous advantages, including high strength and high stiffness-to-weight ratios, good fatigue and corrosion resistance, and high-energy absorption capacity, all of which make them more efficient compared to mechanical fasteners. Many techniques have been used to strengthen ABJs such as use of fillers, hybrid joints, and co-cured joints. The vast majority of studies have been focused on using filler materials for technical and economical reasons. In this study, three types of Nano-fillers (Nano-clay, Nano-silica and Nano-graphene) were used to reinforce epoxy resin. Based on weight content of epoxy; clay, silica, and graphene were added by (1, 2, 3, and 5 %), (1, 2, and 3 %), and (0.1, 0.2, 0.3, 0.4, and 0.5 %), respectively. Glass fiber reinforced polymer plates produced commercially were used as adherends. The experimental results obtained from lap shear test and 3-point bending test, have demonstrated that the three types of Nano-fillers positively affected the joint strength. The highest improvement in shear and flexural strength was obtained by adding graphene particles as 145% and 100%, respectively. As the joint strength increased with the Nano-particle inclusion, the adhesive failure mode of the neat epoxy joints was changing to more and more progressive mode. The most important failure mode was observed in the fracture surfaces of the joints prepared with graphene particles.