FRACTURE LOAD PREDICTIONS FOR ADHESIVE JOINTS

An engineering approach to fracture load predictions for adhesive join ts is presented. The approach is based on the premise that the in-situ strength of the bondline can be characterized by the fracture envelop e (critical energy release rate as a function of the mode of. loading) , for a specific adhesive system. By using the J integral for large de formations together with large-deformation beam theory, a simple close d-form expression is obtained for the energy release rate per unit are a extension when a crack propagates in the bondline of a generalized a dhesive joint (adhesive sandwich). This technique, together with a pub lished method for mode partitioning, enables fracture load prediction by comparing the calculated fracture parameters with the critical ones from the fracture envelope. The approach is shown to predict fracture loads accurately for a variety of joints including the cracked lap sh ear (CLS), the single lap shear (SLS) and the double strap (DS) joint.