Probabilistic fatigue evaluation of notched specimens considering size effect under multiaxial loading

Abstract

Fatigue evaluation of notch components is key to ensuring the structural integrity of grand equipment and implementing fatigue resistant design, while fatigue models that effectively couple multiaxial stress condition, notch and size effects are still lacking. Accordingly, a new probabilistic fatigue model by combining the weakest link theory with critical plane theory is proposed in this work. Firstly, the critical plane location is determined by calculating the stationary point of the relevant strain energy density function. Then, a new effective stress concept is proposed to establish the connection between experimental data of smooth specimens and equivalent stress in the critical damage region of notched specimens. Meanwhile, a critical damage region considering the size effect is defined to determine the effective stress. Finally, the experimental data of EN8 medium carbon steel and Q345 alloy steel are used for model validation and comparison and the results show that the model has a higher accuracy than the other four models. Additionally, the curves P−σeff‾−Nf can effectively describe the fatigue life scatter.