A CLOSED FORM SOLUTION FOR THE ENERGY-RELEASE RATE OF THE DOUBLE CANTILEVER BEAM SPECIMEN WITH AN ADHESIVE LAYER

A simple, yet accurate, strength of materials approach is used to derive a closed form solution for the compliance and energy release rate of the double cantilever beam specimen with an adhesive layer and cohesive cracks. Such capability currently is not available in the literature. The results are valid for either isotropic or orthotropic materials in plane stress or plane strain. The specimen is modelled as a beam partially free and partially supported by an elastic foundation. The solution is an extension of previous work by Kanninen [1] for the special case of a homogeneous material (e.g., no adhesive layer). The closed form results are subsequently verified using the finite element method. Excellent agreement is found for a variety of crack lengths and material properties. It is shown that, for composite adherends, shear deformation must be taken into account in addition to elastic foundation effects. The present results are useful in analyzing test results to determine the fracture toughness of adhesives and composite laminates with adhesive interlayers or resin rich ply interfaces, and in sizing specimens.