Fatigue life prediction of notched components under size effect using stress gradient-based approach

Notch and size effects show vital influence on fatigue performance of engineering components, which deserve particular attention for ensuring their structural integrity and reliability. In this study, the influences of size effect and stress gradient on effective stress as well as fatigue life were studied. Specifically, the effective stress methods were integrated with stress gradient, by which the relationship between stress gradient and size effect was discussed. In addition, a new stress gradient-based method for notch fatigue analysis was proposed by coupling the Weibull model with critical distance theory. Fatigue tests on Ni-based superalloy GH4169 notch specimens with different sizes were conducted at 650 °C, and experimental data of Al 2024-T351 alloy and low carbon steel En3B notch specimens were utilized for model validation and comparison. Results indicate that the proposed method provides more accurate fatigue life predictions than other effective stress methods.