Shear and Fracture Characteristics of Nano-silica and GNP Hybrid Nanoparticle Reinforced Single Lap Joints

Abstract

In the current study, the effects of hybrid nanoparticles on the shear and fracture behaviours of adhesively bonded single lap joints (SLJs) using Aluminum substrates were investigated. To this aim, nano-silica and graphene nanoplatelet (GNP) particles were used as filler materials in Araldite 2014-2 epoxy-based adhesive. The SLJ samples prepared at seven different configurations were subjected to lap shear tests. Additionally, macro and SEM views taken from damaged surfaces of the samples were examined to understand the influence of nanoparticle addition on the fracture characteristics of the joints. The experimental findings showed that all nanoparticle-doped samples, whether single or hybrid, exhibited remarkable improvements in shear strength compared to pure ones. The maximum improvements were obtained from the H2 sample having 1 wt.% nano-silica and 0.5 wt.% GNP. The maximum shear strength was 13.62 MPa which was 213% higher than pure samples (4.35 MPa). It was determined that some toughening mechanisms such as crack deviation, crack bridging and plastic void formations had a crucial role in the enhancements of the samples. However, higher amounts of nanoparticle inclusion such as H4 (1.5 wt.% nano-silica+1 wt.% GNP) showed a decrease in shear strength, compared to the maximum one, due to the material degradation caused by agglomerations. In conclusion, nano-silica and GNP particles proved they could be used together by exhibiting a synergetic effect in the adhesive joints.