Creep-fatigue life prediction under fully-reversed multiaxial loading at high temperatures

A multiaxial fatigue damage parameter based on the critical plane approach was proposed to calculate the pure fatigue damage under uniaxial/multiaxial loading at constant high temperatures. For the fully-reversed low-cycle fatigue loading under low frequency at high temperature, one-half of the maximum equivalent stress response value at cyclic stabilization is used as the creep stress to evaluate the multiaxial creep damage. The linear damage accumulation rule is used to predict the multiaxial creep-fatigue life at high temperature. The creep-fatigue experimental data of thin tubular specimens with GH4169 superalloy and 2.25Cr-1Mo steel were used to verify the proposed creep-fatigue life prediction model. The results showed that the proposed creep-fatigue damage calculation model can be used under either uniaxial or multiaxial nonproportional loading at high temperature. The proposed model is used to predict multiaxial creep-fatigue life, and a good agreement is demonstrated with experimental data.