Influence of adhesive thickness and filler content on the mechanical performance of aluminum single-lap joints bonded with aluminum powder filled epoxy adhesive

The objective of this study was to develop information on the influence of adhesive thickness and aluminum filler content on the mechanical performance of aluminum joints bonded by aluminum powder filled epoxy. The adhesive strength of the joints was determined by utilizing the single-lap shear test. The influence of adhesive thickness and aluminum filler content on stress distribution within the adhesive was also analyzed by finite element method (FEM). Both FEM analysis and the experimental investigation show that in general adhesion strength decreases as the thickness of the adhesive increases. It is observed from the predictions (FEM simulations) that the stress level increases at the adhesive-metal substrate interface as the aluminum filler content in the adhesive increases. Experimental results show that epoxy adhesive retains its strength up to the 50 wt% aluminum filler content. The joints fail in cohesive mode (failure within the adhesive) due to the high stress levels generated in the adhesive, which indicates that the adhesion to the metal surface is stronger than that of the interior part of the adhesive.