Study on fatigue life prediction of fiber-reinforced composites under non-constant load

When subjected to variable loading, the development of fatigue damage in fiber-reinforced composites is markedly impacted by the interactive effects between different loads. The presence of these effects highlights the limitations of traditional linear damage approaches, which struggle to capture the fatigue life of materials with sufficient accuracy under intricate loading histories. To address this limitation, this paper integrates the mechanisms of fatigue crack propagation with nonlinear damage evolution theory to explore the specific impact of load sequence effects on the fatigue life of fiber-reinforced composites. Based on this analytical framework, a novel fatigue life prediction model is proposed, which accommodates adjustable stress ratios and incorporates load interaction factors. To validate the model's effectiveness, it is compared with traditional Miner models, Aeran models, their improved versions, and the Aodi Yu model, using typical experimental data from fiber-reinforced composites for empirical analysis. The analysis confirms that the proposed model exhibits clear advantages over classical linear damage formulations, offering significantly better accuracy in fatigue life estimation and effectively capturing the influence of load interactions.