Predictive strength-fracture model for composite bonded joints

A new strength-fracture model is proposed for the formulation of decohesion elements, which are implemented in finite element models to predict failure of bonded joints. The proposed model unifies criteria for strength to predict failure initiation and criteria for fracture to predict failure progression. The initiation and progression of interfacial cracks and/or cohesive cracks are simulated by positioning decohesion elements at the adherend–adhesive interface and between bulk adhesive elements. Geometric nonlinearity of the adherends and adhesive are included in the finite element formulation. Simultaneous cracks and their paths are predicted for static equilibrium configurations of the following joint configurations: double cantilever beam, single lap joint, and the crack lap shear. Qualitative and quantitative between finite element analyses predictions and experimental results for quasi-static loading of these joint configurations were found to be in general agreement.