Compact solutions for the corner singularity in bonded lap joints

This paper presents compact solutions of the corner singularity at the adhesive/adherend interface in a bonded lap joint. Two configurations of special importance to evaluating joint strength are considered: corners pertaining, respectively, to a square edge and a spew fillet. The stress intensity factors are determined for the limiting case of rigid substrates by means of a numerical matched asymptotic expansion method. The non-dimensional stress intensity factor depends only on the Poisson's ratio of the adhesive, and this variation is characterised in a convenient analytical form by polynomial expressions. Comparison with finite-element results of a bonded joint obtained using fine mesh near the corner points confirms that the present analytical solutions provide very good representations of the singular stress fields at adhesive/substrate corners.