The prediction models for fatigue crack propagation rates of mixed-mode I-II cracks

Abstract

The Manson–Coffin law for the low-cycle fatigue of a representative volume element and the fatigue crack propagation rate of a cracked component are crucial for characterizing the fatigue resistance of a material. Using the average plastic-strain-energy density and the average linear damage accumulation in the plastic zone at the crack tip, two fatigue crack growth models for mixed-mode I-II cracks, without artificial parameters, are proposed, based on the low-cycle fatigue properties of a representative volume element under cyclic plastic strain. For 30Cr2Ni4MoV rotor steel, the proposed models are used for theoretically predicting the mixed-mode I–II fatigue crack propagation rates of compact tension shear specimens subjected to loadings at four different loading angles; and the theoretical prediction results are found to be consistent with the experimental ones.