Comparison between 2D and 3D applications of the coupled criterion to crack initiation prediction in scarf adhesive joints

Crack initiation of scarf adhesive joints with similar adherends is predicted through 2D and 3D applications of the coupled criterion. The joint adhesive crack initiation topology and loading are determined as a function of the joint angle and of the specimen width, using both an energy and a stress criterion consisting of the maximum interface normal or shear stress to strength ratio. Adherend/ adhesive interface strength and toughness are determined by indirect confrontation to experimental results under tensile loading. The blind application of the proposed method to crack initiation of scarf adhesive joints under bending leads to a good agreement with experimental data. Compared to the 2D case, the 3D application of the coupled criterion allows determining the crack topology and leads to a slight better agreement with experimental results.