Compressive failure and kink-band formation modeling

To increase the use of polymeric structural composites, a major issue is to properly account for intra-laminar failure mechanisms, such as fiber kinking induced under compression. We propose a new continuum damage model that can predict the fiber kinking response at the ply level. The model is based on a previous structure tensor-based model for the response of UD-plies. A novel feature is that the compressive UD-ply response at the macroscale includes the effect of the fiber misalignment shaped as a kink-band that is resolved at the sub-scale. Concepts of computational homogenization are used to include the fiber-shear of the kink-band at the sub-scale. The model calibration is adapted to account for either kink-band formation or shear-splitting depending on the off-axis loading. Finally, the model is validated at the laminate level against experimental data for OHC-tests available in the literature. A good agreement is found for predicted strength values and observed fracture patterns of the laminates. The size effect experienced when different hole sizes are tested is also addressed.