Modeling delamination migration in composite laminates using an enhanced semi-discrete damage model (eSD2M)

Abstract

This paper presents an extension of the semi-discrete damage model (SD2M) (Nguyen and Waas, 2020a,b), implemented using the finite element (FE) method, to capture the interaction of intra-laminar matrix cracks and inter-laminar failure (delamination migration). In the enhanced semi-discrete damage model (eSD2M), the plies are modeled with continuum finite elements and the interlayers are represented with cohesive elements. A meshing strategy is presented to create compatible meshes for interlayers in order to capture a proper load transfer between the laminae and the interfaces. The material pre-peak non-linearity of the composite is modeled with Schapery theory (ST), the post-peak strain softening is captured with the crack band (CB) method including a mixed-mode law for matrix failure. For the cohesive behavior of the interfaces, a novel mixed-mode traction–separation law is proposed. The model is validated on the basis of a ply-scaled quasi-isotropic open-hole tensile (OHT) laminate that shows a delamination-dominated failure. The eSD2M model is able to capture major matrix cracks at the hole including 0° splitting as well as distributed matrix cracks and free edge cracking. The present model is capable of predicting the delamination migration mechanism with an accurate peak load and the total failure due to fiber tensile rupture in a realistic manner.