A new creep–fatigue damage cumulative model is proposed under multiaxial thermomechanical random loading, in which the damage at high temperature can be divided into the pure fatigue damage and the equivalent fatigue damage from creep. During the damage accumulation process, the elementary percentage of the equivalent fatigue damage increment is proportional to that of the creep damage increment, and the creep damage is converted to the equivalent fatigue damage. Moreover, combined with a multiaxial cyclic counting method, a life prediction method is developed based on the proposed creep–fatigue damage cumulative model. In the developed life prediction method, the effects of nonproportional hardening on the fatigue and creep damages are considered, and the influence of mean stress on damage is also taken into account. The thermomechanical 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 model. The results showed that the proposed method can obtain satisfactory life prediction results.

中文翻译：

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多轴热机械随机载荷下基于等效疲劳的累积损伤模型

提出了一种新的多轴热机械随机载荷下的蠕变疲劳损伤累积模型，该模型将高温损伤分为纯疲劳损伤和蠕变等效疲劳损伤。在损伤累积过程中，等效疲劳损伤增量的基本百分比与蠕变损伤增量的基本百分比成比例，蠕变损伤转换为等效疲劳损伤。此外，结合多轴循环计数方法，基于所提出的蠕变疲劳损伤累积模型，开发了寿命预测方法。在发达的寿命预测方法中，考虑了非比例硬化对疲劳和蠕变损伤的影响，并且还考虑了平均应力对损伤的影响。利用GH4169薄壁管状试件在多轴恒定振幅和可变振幅载荷下的热机械疲劳实验数据验证了该模型的正确性。结果表明，该方法可以取得满意的寿命预测结果。