Creep behaviour of a graphene-reinforced epoxy adhesively bonded joint: experimental and numerical investigation

In this paper, the creep behaviour of aluminium to aluminium adhesively bonded joints reinforced with different amount of graphene nano-platelets (up to 0.5 wt %) was investigated experimentally and numerically. The mechanical properties of the neat and reinforced epoxy adhesive, as well as their creep behaviour were obtained by tensile tests and creep tests in three stress levels, respectively. The nonlinear Norton-Bailey creep model was used to obtain the creep behaviour of the neat adhesive. The effect of graphene content, up to 0.5 wt%, on the creep behaviour of the reinforced adhesive was also simulated by a new function, called graphene function. It was observed that the presence of graphene up to 0.5 wt% continuously reduced the creep strain of the epoxy adhesive. In the next step, the aluminium to aluminium single lap joints (SLJs) bonded by the neat and reinforced adhesive were subjected to simple tensiles and creep tests. It was observed that the optimum graphene content to increase the tensile strength and the creep resistance of the SLJs were 0.1 wt% and 0.25 wt%, respectively. Finally, the creep behaviour of the SLJs with various graphene content was analysed by finite element method (FEM) using the new creep model developed in this paper. The results show that the numerical creep displacement of the SLJs boned by the neat and graphene reinforced adhesive up to 0.25 wt% are in good agreement with experimental ones.