Generalized technique for cumulative damage modeling of composite laminates

This article introduces an iterative model to predict the fatigue behavior of fiber reinforced laminated composites under general loading conditions. The model simulates the damage progress and subsequent material property degradation of composite laminates and predicts their fatigue life by using a three-stage procedure. In the first stage, state of stresses in the whole component is specified. Then, multi-axial stresses of each element are utilized to damage assessment by using a newly developed damage estimation technique. Considering each element as an orthotropic material, stiffness degradation due to the induced damage is calculated based on two sets of material property degradation rules. For this aim, a generalized approach is used for gradual and sudden material property degradation. In order to evaluate the model, a macro program is developed that simulates the fatigue behavior of unidirectional and multidirectional composite laminates. The results of the model are consistent with available experimental data. Using this program, some fatigue life predictions are also accomplished for laminates with arbitrary stacking sequences.