Geometric discontinuity effect on creep-fatigue behaviors in a nickel-based superalloy hole structure considering ratcheting deformation

Abstract

Multi-axial stress states are common in the most high-temperature components. In this paper, a ratcheting modified strain energy density exhaustion (RM-SEDE) model is developed to predict creep-fatigue life for hole structures. Afterwards, the numerical procedures are perfected to provide in-depth understandings in cyclic deformation, damage evolution and life prediction under multi-axial stress states. Some abnormal results contrary to uniaxial common sense, in terms of creep-fatigue life distributions and geometrically necessary dislocation accumulations, are well resolved based on the RM-SEDE. Among them, not only life prediction accuracy is improved, but also deterioration mechanism of ratcheting on creep-fatigue damage is explained.