A Blended Damage and Fracture Mechanics Model for Progressive Damage Analysis of Notched Composite Structures

This paper presents a blended continuum damage and fracture mechanics finite element model for the progressive damage analysis of composite structures subjected to quasi-static loading. Continuum damage modeling, utilizing the failure criterion of Puck, was used to predict the damage initiation of matrix cracks and fibre failures, while fracture mechanics was used to model onset and propagation of delamination and the propagation of matrix cracks. Numerical implementation was performed in the commercial software ABAQUS, extended with user subroutines for material constitutive behaviour. The numerical framework was validated using experimental results found in literature of open-hole specimens subjected to tensile loading. As the main focus was given on the capability of the model to predict different failure patterns, the ply-block effect was investigated using a [45n/90n/-45n/0n]s with n=1,2,4,8 lay-up made of IM7/8552 composite prepreg. The proposed model was benchmarked against a model that uses only continuum damage approach and it was found that it can predict accurately the failure load the damage pattern especially when delamination is the dominant damage mechanism and interacts with matrix cracking, while the other model fails to predict even the failure load.