Numerical analysis of effect of the substrate geometry and tensile load on the strength of bonded single lap joint

Abstract

Abstract With the development of structural adhesives, single joint assemblies have increasingly become the most widely used assembly process in many industrial fields and even in civil engineering due to their simple geometry and structural efficiency. The resistance of the assembly requires a careful analysis of the behavior of the adhesive joint since the latter has the weakest mechanical properties compared to the adherents. several solutions have been proposed in order to improve the mechanical strength of the assembly by taking into consideration modifications to the edges of the adhesive and of the two adherends in order to attenuate as much as possible the high concentration of stress at the level of the adhesive. In this study, a 3D numerical model was developed by Abaqus to evaluate the influence of changes in the geometry of the edges of the adherends and the adhesive on the mechanical strength of a single lap joint under uniaxial tensile stress. Two geometric configurations have been proposed, taking into account an adhesive fillet and a removal of material at the level of the free edges of the adherends. The objective is to analyze the impact of these geometric modifications on the reduction of the concentration of stresses on the one hand of the assembly and more particularly on the adhesive and to explore how this new design of the joints can contribute to improve shear and peel strength of bonded joints. In this respect, several parameters have been highlighted, namely the value of the applied stress, adhesive thickness and length, adherends thickness, adhesive fillet and modified free edge of the adherends on the value of the Von Mises stress in the assembly and in the adhesive joint. The results show clearly that a geometric modification at the two free edges of the two adherends and adhesive markedly improves the strength of the assembly and reduces the high stress concentration in the adhesive.