Influence of superposition length on mechanical resistance of single-lap adhesive joints

Abstract

The present work studies the mechanical behaviour of single-lap joints of PP reinforced with glass fibres. Failure loads were obtained experimentally for different superposition lengths (15, 30, 45 and 60 mm). A 2D numerical analysis was developed using the finite element method, and assuming a plane strain state, an orthotropic behaviour for the laminates and an elastic-plastic behaviour for the adhesive. It was found that the positions where [sigma]yy and [tau]xy stresses have their maximum values, which are near the extremities of the joint and close to the interface adhesive/adherends, move inside the joint with load increasing. An equivalent stress was defined from [sigma]yy and [tau]xy and was obtained for the failure loads obtained experimentally. This quantity varies 9.7% with superposition length, which can be considered reasonable therefore can be used as a damage criterion for single-lap joints.