ABSTRACT Accurate fatigue life prediction is critical for structural integrity assessment, typically requiring simultaneous consideration of the coupled effects of low‐cycle fatigue (LCF) and ratcheting. In this study, asymmetric stress‐controlled LCF tests were conducted on smooth and notched specimens of P92 at 600°C and IN718 at 650°C. It was found that the notched specimens exhibited significantly lower overall ratcheting strain than the smooth specimens, attributed to notch‐root stress support. Traditional approaches (e.g., the Manson–Coffin model) show noticeable discrepancies for notched components under asymmetric cyclic loading because ratcheting and notch effects are typically neglected. Based on a damage‐evolution framework, a fatigue life model incorporating a stress gradient factor is proposed to account for notch influence. The resulting predictions for all cases fall within the ±2 scatter band, indicating a substantial improvement in predictive accuracy.
Hua et al. (Wed,) studied this question.