A Simplified Approach to Fatigue Damage Modelling of Composite Laminates with Stress Concentration: Regional Elements Model

In this research, a new model is established based on progressive fatigue damage and critical element models to simulate fatigue behaviour and predict the fatigue life of composite laminates with stress concentration. This model, called the “regional elements” model, has three major parts: stress analysis, failure analysis, and material property degradation. A critical region of the analyzed composite laminate is considered and the elements of this region are divided into critical and sub-critical layers. Using 2- dimensional stress analysis, failure modes of these regional elements are investigated and material properties in the critical and sub-critical layers are changed according to sudden and gradual material property degradation rules. Gradual material property degradation is performed on the longitudinal tensile strength of critical layers and the longitudinal tensile stiffness of sub-critical layers. By the iteration of the aforementioned loop, fatigue damage modelling is completed and an estimate of the fatigue life of a composite laminate is obtained. The finite element method is used to assess the capabilities of the current model through a user-friendly computer programme. The model predicts initial and final failure loads to within 20% of experimental results for the case of static failure analysis. However, 3-dimensional stress and failure analyses are required to improve the model for fatigue failure analysis for all the configurations.