In this paper, a dual-scale modelling approach is developed to investigate creep-fatigue behavior and predict crack initiation life for holed structures under multi-axial stress state. The macro-scale simulation supplies local deformation histories to the dual-scale simulation as boundary conditions. In the dual-scale simulation process, the micro-mechanical behavior and damage evolution are described by using crystal plasticity. In order to validate the dual-scale simulation procedures, a series of creep-fatigue tests as well as the post-test characterizations were carried out for nickel-based Inconel 718 at 650 ℃. The detailed results of macro- and micro-scale simulations are presented in terms of stress–strain behavior, damage evolution and life prediction. Regarding the macro-scale simulations as the benchmark, it may provide an assistant support and precognition for the micro-scale damage calculation at higher cycles. The predicted cycle numbers to crack initiation are in agreement with the experimental ones. More advantages are manifested in the potential scientific and engineering significance for the dual-scale modelling approach.

在本文中，开发了一种双尺度建模方法来研究蠕变疲劳行为并预测多轴应力状态下带孔结构的裂纹萌生寿命。宏观尺度模拟为双尺度模拟提供局部变形历史作为边界条件。在双尺度模拟过程中，利用晶体塑性来描述微观力学行为和损伤演化。为了验证双尺度模拟程序，在 650 ℃下对镍基 Inconel 718 进行了一系列蠕变疲劳测试以及测试后表征。宏观和微观模拟的详细结果在应力-应变行为、损伤演变和寿命预测方面给出。以宏观模拟为基准，它可以为更高周期的微尺度损伤计算提供辅助支持和预知。裂纹萌生的预测循环数与实验结果一致。更多的优势体现在双尺度建模方法的潜在科学和工程意义。