Numerical simulation of mono- and bi-adhesive aluminium lap joints

Abstract

In single-lap bonded joints the stresses are maximum at the edges, where failure usually begins, while in the centre stresses are the lowest. Stress concentration towards the ends of a bonded lap joint depends, to some extent, on the relative stiffness of the adherend and the adhesive used. For a given adherend, the lower the stiffness of the adhesive used in the bondline, the lower the stress concentration, giving rise to potentially higher joint strength. This paper discusses the failure mechanism of bi-adhesive joints, where a flexible adhesive is used at the joint edges, while a less ductile adhesive is used in the centre of the overlap. The results show an increase in shear strength of the bi-adhesive-bonded joints compared with those in which single adhesives were used over the full length of the bondline. The increase of the apparent lap-shear strength was qualitatively predicted, through finite element modelling.

Keywords:

• BI-ADHESIVE JOINTS
• FINITE ELEMENT ANALYSIS
• LAP-SHEAR JOINTS
• ALUMINIUM ALLOY
• FAILURE