Performance of bi-adhesive bonded aluminium lap joints

The stress concentration towards the ends of a bonded lap joint depends to some extent on the relative stiffnesses 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. The paper presents the results of a study of the application of two adhesives with different stiffnesses along the overlap length in single lap joints. A stiff adhesive was applied in the middle portion of the overlap, while a low modulus adhesive was applied towards the edges prone to stress concentrations. The results show measurable increase in strength of the bi-adhesive bonded joints compared with those in which single adhesives were used over the full length of the bondline. (C) 2003 Elsevier Science Ltd. All rights reserved.