Rubber-like adhesive in simple shear: stress analysis and fracture morphology of a single lap joint

Abstract

In contrast to classical studies of the single lap specimen involving structural, high modulus adhesives, this paper presents an analysis for the case of a rubber-like adhesive. The behaviour of a silicone rubber in simple shear is determined experimentally, and specific fracture surfaces, consisting of a succession of tilted planes, are obtained whenever failure occurs at very high shear strains. Assuming plane-strain conditions, and nearly-incompressible behaviour given by the Mooney-Rivlin constitutive law, finite element computations were carried out. They indicated that the stress field was surprisingly unifonn, and that free boundary effects were quite limited. A dominant tensile stress arises along the shearing direction, as a result of large deformations. Comparison of the fractured surfaces with the stress field computed at very high shear strain suggests that crack propagation first occurs in the opening mode inside the rubber film, and not along the interfacial planes; the ends play no particular role in the joint failure.