The fracture load analysis of different support patches in adhesively bonded single-lap joints

Abstract

Adhesively bonded joints are frequently used in the aviation and automotive industries. Bending appears in the bonded materials as a result of eccentric loading when tensile loading is applied to an adhesively bonded single-lap joint (SLJ) geometry. As a result of this bending, moment effect occurs in the overlap region in the joints joined with the adhesive. This moment effect causes peel stresses at the edges of the overlap region of the joint such that these stresses are the main reasons of the damage in the joint. Obviously, reductions in these stresses should result in higher joint strength and increased load capacity. In this study, support patches were added at a varying distances from the overlap region to decrease the bending effect occurring in adhesively bonded single-lap joints. In the study, adhesive bonded single-lap joints were produced by using DP460 liquid structural epoxy as the adhesive, AA2024-T3 aluminum alloy as the adherend and flat or curved AA2024-T3 aluminum alloy and AISI 304 steel with different thickness as the support patches. As a result, when the failure load obtained from the experiments was examined, the use of support patches in single-lap joints increased the damage load of the joint between approximately 16% and 94%. However, such increases in the damage load are highly dependent on the type, thickness, geometry (flat or curved) and positioning of the support patches.