Mechanical performance and damage analysis of GNP-reinforced adhesively bonded joints under shear and bending loads
Mehmet Veysel Çakır, Özkan Özbek
Abstract
In this study, the mechanical response and damage characteristics of single lap joints (SLJs) including graphene nanoplatelets (GNPs) were investigated under tensile and three-point bending tests. To this end, Aluminum 2024 substrates were bonded by Araldite 2014–2 adhesive reinforced by GNP with various percentages as 1%, 2%, 3%, and 4% by weight. The results demonstrated that GNP added samples exhibiting a higher ability to resist loads showed better performance for both experiments compared to pure samples. The maximum improvements in the 3 wt.% GNP added samples were obtained as 91.2% in the lap shear test and 45.1% in the three-point bending test. The addition of GNP to the adhesive acted as a barrier against growing cracks, causing the formation of special toughening mechanisms such as crack deviation, bridging, and pull out, which either stopped the cracks or deviated them from their path. These mechanisms improved the fracture characterization of samples in failures. However, more amount of GNP higher than 3 wt.% led to sharp decreases due to the non-uniform local stress concentrations as a result of agglomerations.