A discrete crack informed 3D continuum damage model and its application for delamination migration in composite laminates

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An accurate characterization of intra- and inter-laminar damage is essential for the prediction of the damage onset and evolution in composite laminates. This paper presents a discrete crack-informed 3D continuum damage mechanics (CDM) model and its application for the simulation of delamination migration in tape laminates. The proposed approach aims at capturing the initiation and propagation of discrete matrix cracks and their interactions with interface delaminations without introducing a physical crack along with its explicit front tracking. The 3D Hashin failure criteria are employed first to predict the damage initiation of composite materials under an arbitrary stress state. A crack orientation-dependent damage evolution model is developed to dictate the composite stiffness degradation associated with a matrix crack plane. The matrix crack plane is parallel to the fiber direction and its orientation is determined by the maximum principal stress in the transverse plane. The corresponding matrix crack-informed stiffness is degraded based on the orientation of the crack plane. To alleviate mesh dependency within a continuum damage modeling framework, an energy-driven failure mechanism is adopted for characterizing damage evolution of matrix cracking and fiber breakage. By coupling the discrete crack informed model for intra-laminar damage prediction and the cohesive model for interface delamination within the same CDM framework, their synergistic interaction can be captured during the progressive failure analysis of composite laminates. The predictive capability of the enhanced modeling strategy is examined through its application of a delamination migration problem with the presence of the delamination initiation and migration via matrix cracking. The matrix cracks and delamination growths are captured for different loading positions without a pre-assumption on the failure mode. Good agreement is achieved by comparing the predictions with the experimental data from a published NASA report.