Progressive Failure Analysis of Adhesive Bonded Joints with Laminated Composite Adherends

The paper presents novel 3-D variational approach aimed at analyzing crack propagation in adhesively bonded composite joints. The analysis is based on the 3-D mosaic model of a composite body allowing for step-wise material property variations in all three coordinate directions, and variational principle of minimum total potential energy. The displacement field in a composite structure is approximated for all coordinate directions in terms of triple series with Bernstein basis functions. The progressive failure analysis approach utilizes critical strain energy release rate criterion to predict various scenarios of the adhesive, cohesive or interlaminar crack propagation. Several cracks of the same type or different types can be analyzed simultaneously. Two numerical examples consider double-lap adhesive bonded joint of unidirectional and cross-ply laminated composites. The results for the "sliding" and "opening" displacements show that for the bonded joint and loading conditions under consideration, both Mode I and Mode II significantly contribute to the progressive failure process.