Fatigue life prediction with a normalized damage driving stress model under variable-amplitude loading

Accurate fatigue life prediction under variable-amplitude loading (VAL) is pivotal to ensuring the structural integrity and reliability of engineering components. To this end, an accurate and user-friendly model is proposed, grounded in the concept of normalized damage driving stress, wherein the load interaction effect is readily captured through a newly introduced factor that is defined as a function of loading parameters. Moreover, complete application procedures for both multistep loading and combined high- and low-cycle loading conditions are provided, without requiring fitting parameters. Extensive experimental results on ten metallic materials are used to validate the proposed model. The results demonstrate that, compared with six existing models, the proposed model offers improved predictive accuracy and broader applicability, highlighting its good potential for life-prediction tasks under VAL conditions.