Reference Stress Based Assessment for Creep-Fatigue Life Under Multiaxial Condition

The reference stress method has been developed to assess the service life for many components under creep condition. However, in order to use the reference stress as a representative stress to assess the creep fatigue life, some modifications are needed. The σ_d approach based on reference stress, used in RCC-MR, is one of the most common method to assess creep fatigue crack incubation. The aim of this paper is to develop a novel model based on reference stress and the σ_d approach to estimate the life subjected to creep-fatigue interaction under multiaxial condition for defect free structures. Three kinds of circumferentially notched bar specimens were used in order to examine the creep-fatigue interaction under multiaxial conditions. Finite element analyses were conducted to develop a simplified life assessment method and to calculate the creep fatigue damage in the test specimens. The predicted creep fatigue lives are in good agreement with the experimental results using notched bar specimens of 316H stainless steel.