Prediction of fatigue damage region with the use of the notch critical plane approach for crack initiation and propagation

The advanced volumetric approaches are reviewed briefly to state the stress/strain-based or energy-based parameters of fatigue damage region are critical. A new approach is proposed to distinguish crack initiation and propagation stage. The angles of crack initiation are predicted by notch critical plane (NCP) approach (Luo et al. Fatigue Fract Eng Mater Struct, 2019, 42(4): 854-870). NCP is the plane which passes through the fatigue critical point (FCP) and undergoes the maximum shear stress amplitude. The experiment of thin-walled round tube components is conducted to check these approaches. The direction of crack initiation is basically the same as that of NCP. Most of the predicted lives fall within an error factor of 3.