ABSTRACT To address the challenge of predicting material fatigue life under variable‐amplitude loading, this paper proposes an improved Manson–Halford (M‐H) nonlinear cumulative damage model. The enhanced model comprehensively considers load interactions and material property parameters. Firstly, the strength degradation coefficient is derived by establishing a novel residual strength model requiring no additional parameter fitting. Combined with the load amplitude ratio, this effectively captures the coupled effects of load interaction and strength degradation. Secondly, the elastic modulus parameter is introduced to modify the characteristic exponent of the fatigue life ratio in the M‐H model, thereby enhancing the sensitivity of fatigue damage to different materials. Finally, validation against experimental data from six different metallic materials under two‐level and multilevel loading conditions demonstrated that this model exhibits superior robustness and predictive accuracy compared to other modified M‐H models. This model provides a more physically grounded and readily applicable tool for fatigue life assessment under complex loading conditions.
Wu et al. (Sun,) studied this question.