Thermo-mechanical fatigue life prediction method under multiaxial variable amplitude loading

Abstract

Based on the Wang-Brown method, a time-dependent multiaxial cycle counting algorithm was proposed under multiaxial thermomechanical variable amplitude loading. By using the proposed multiaxial cycle counting algorithm, a new thermo-mechanical fatigue life prediction method was proposed, in which the pure fatigue damage, creep damage, and the interaction damage taking into account the interaction modulus varying with temperature were calculated for each reversal counted by the cycle counting algorithm. Three types of damage from all the counted reversals for the whole strain-time history were accumulated, and the thermo-mechanical multiaxial fatigue life can be predicted. The thermo-mechanical fatigue experimental data for thin-walled tubular specimen of superalloy GH4169 under multiaxial constant amplitude and variable amplitude loadings were used to verify the proposed method. The results demonstrated that the proposed method can provide very satisfactory prediction results.