On a robust FE2 model for delamination analysis in composite structures

The present paper deals with a robust two-scale delamination model based on a FE2 formulation, whereby a finite element model on the macro- and meso-scale are solved simultaneously. For a correct modeling of the delamination kinematics, the composite structure on macro-scale is discretized by a combined element. Only one single integration point over the full height of the composite structure contains the information about shell and interfacial kinematics, allowing a straight forward enhancement to the FE2 model. On the meso-scale, the combined kinematics are applied to a coupled representative volume element (cRVE), which describes the entire stacking sequence including an interfacial layer. The coupling between the shell and the interfacial kinematics results in a more robust delamination model. Numerical examples demonstrate the applicability and the improvements by reducing the oscillations of the load displacement curve during the softening process and the influence of the macroscopic mesh discretization under single and mixed mode loading.