A fatigue–oxidation–creep damage model that can take into account the effect of multiaxial cyclic feature on the damage mechanism is proposed under axial-torsional thermo-mechanical fatigue loading. In the proposed model, the effects of non-proportional additional hardening on fatigue, oxidation, and creep damages are considered, and the variation of oxidation damage under different high temperature loading conditions is also described. Moreover, the intergranular creep damage needs to be equivalent to the transgranular damage before accumulating with the fatigue and oxidation damages. The fatigue, oxidation, and creep damages can be expressed as the fractions of fatigue life, critical crack length, and creep rupture time, respectively, which allows the linear accumulation of different types of damages on the basis of life fraction rule. In addition, the proposed model is validated by various fatigue experimental results, including uniaxial thermo-mechanical fatigue, axial-torsional thermo-mechanical fatigue, and isothermal axial-torsional fatigue under proportional and non-proportional loadings. The results showed that the errors are within a factor of 2.

中文翻译：

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轴向扭转热机械载荷下的疲劳-氧化-蠕变损伤模型

提出了一种在轴向扭转热机械疲劳载荷下考虑多轴循环特征对损伤机制影响的疲劳-氧化-蠕变损伤模型。该模型考虑了非比例附加硬化对疲劳、氧化和蠕变损伤的影响，并描述了不同高温载荷条件下氧化损伤的变化。此外，在累积疲劳和氧化损伤之前，晶间蠕变损伤需要等价于穿晶损伤。疲劳、氧化和蠕变损伤可以分别表示为疲劳寿命、临界裂纹长度和蠕变断裂时间的分数，这允许基于寿命分数规则的不同类型损伤的线性累积。此外，所提出的模型还得到了各种疲劳实验结果的验证，包括在比例和非比例载荷下的单轴热机械疲劳、轴向扭转热机械疲劳和等温轴向扭转疲劳。结果表明，误差在 2 倍以内。