On the determination of the cohesive zone properties of an adhesive layer from the analysis of the wedge-peel test

An extensive numerical study of the mechanics of the "wedge-peel test" is performed in order to analyze the mode I steady state debonding of a sandwich structure made of two thin plastically deforming metallic plates bonded with an adhesive. The constitutive response of the metallic plates is modeled by J2 flow theory, and the behavior of the adhesive layer is represented with a cohesive zone model characterized by a maximum separation stress and the fracture energy. A steady-state finite element code accounting for finite rotation has been developed for the analysis of this problem. Calculations performed with the steady-state formulation are shown to be much faster than simulations involving both crack initiation and propagation within a standard, non-steady-state code. The goal of this study is to relate the measurable parameters of the test to the corresponding fracture process zone characteristics for a representative range of adherent properties and test conditions. An improved beam bending model for the energy release rate is assessed by comparison with the numerical results. Two procedures are proposed for identifying the cohesive zone parameters from experimental measurements.