Fatigue damage accumulation model and residual life prediction method of composite laminates based on strength degradation

This paper proposes a residual fatigue life prediction method that considers the loading interaction effect, to predict the fatigue life of composite laminates under variable amplitude loading. Based on the study of static mechanical and fatigue properties of composite laminates, the influence mechanism of the loading interaction effect on material fatigue life is analyzed, and an exponential function including adjacent load amplitudes and fatigue life is proposed as a parameter to describe the loading interaction effect. Then, an equation describing the damage evolution of composite laminates during fatigue is proposed. A simple prediction method for residual fatigue life under variable loading considering the loading interaction effect is proposed based on the damage equivalent theory. Finally, through experimental validation, it is found that the prediction error of the proposed model does not exceed 50%, which is lower than the other models mentioned in the paper.