The behaviour of single lap joints under bending loading

Abstract

Four-point bend tests were performed on single lap joints with hard steel adherends and a structural epoxy adhesive. The effect of the overlap, the adherend thickness and the adhesive thickness was studied. It was found that the length of the overlap has no significant effect on the strength of the joints. This is because the load transfer is occurring in a very localised area around the edges of the overlap, being the failure governed by peel mechanisms. The thickness of the adherends strongly affects the strength of the joints. The thicker the adherend, the stronger is the joint. The experimental results are compared with a finite element model and reinforce the fact that the failure takes place due to local strains at the ends of the overlap in tension. An analytical model is also given to predict in a simple but effective way the joint strength and its dependence on the adherend thickness.

Keywords:

• epoxy
• steel
• single lap joint
• bending
• finite element analysis
• analytical model

Acknowledgement

One of the authors, E.F. Karachalios, would like to thank the Needham Cooper Foundation for supporting the research work by means of a scholarship.