Progressive fatigue damage modeling of laminated composites using a novel combined fatigue life model

The progressive fatigue damage (PFD) model is a comprehensive method to simulate the fatigue damage behavior of laminated composites under multiaxial cyclic stress. The generalized material property degradation (GMD) technique is a component of the PFD model. Also, the fatigue life modeling of a UD ply under a uniaxial state of stress is a subcomponent of the GMD technique. The present article compares and evaluates the results achieved by using different fatigue life models within the GMD technique. For this purpose, three commonly used fatigue life models (the normalized fatigue life model, the Luders fatigue life model, and the unified fatigue life model) were considered. Based on the capabilities of these models in predicting the fatigue life of unidirectional plies, a combined fatigue life model is developed and integrated into the progressive fatigue damage model. The results demonstrate that using the combined fatigue life model improves the prediction accuracy of the PFD model.