Fracture Strength of Multi-layered Composite Plates with Circular Delamination

The critical review and comparison of the different fracture criteria based on Linear Elastic Fracture Mechanics is presented in the paper. The comparison was made on the example of multilayered composite plate with circular delamination made of graphite/epoxy AS4/3501-6 material subjected to biaxial compression. Such structures subjected for compressive loading are mainly exposed for buckling and delamination propagation with the complex form of the gap opening occurs. It requires appropriate selection of the fracture model. It was observed that often used linear models are not able to accurate prediction of the critical loading. Good fitting to the experimental tests was achieved with the use of nonlinear 3D criteria which take into account interaction between particular fracture modes. Presented methodology allow for suitable selection of the multiaxial fracture model for analysis of multilayered composite structures.