A new nonlinear fatigue cumulative damage model based on load interaction and strength degradation

A new nonlinear fatigue cumulative damage model is proposed to address the challenge of insufficient accuracy in calculations stemming from nonlinear cumulative damage models that fail to account for strength degradation effects and interactions among multi-level loads. This model, an enhancement of the Aeran fatigue damage model, incorporates stress ratios to capture load interactions and includes a logarithmic residual strength degradation model extended to multi-level stress states. Comparative analysis of this model against the Miner model and two other models across various material fatigue datasets shows superior predictive accuracy. Specifically, the new model demonstrates a 74.43% improvement over the Aeran model under six-level loading conditions. Its straightforward mathematical formulation makes it practical for engineering applications in fatigue life prediction.