In this work, three dual-scale modelling approaches containing sub-modelling approach, coupled modelling approach and full-field crystal plasticity finite element (CPFE) approach are implemented for notched structures under creep-fatigue loading conditions. Based on the comprehensive comparisons, the sub-modelling approach is determined to be an optimal simulation strategy among them. Furthermore, the combined effects of grain orientation and stress concentration on crack initiation are investigated by adopting the sub-modelling approach. Under low stress concentration factor, the most potential positions of crack initiation randomly locate at the root of geometric discontinuities owing to the influence of grain orientation distribution. With the increase in stress concentration factor and decrease in the number of grains at hotspots, the cooperative relation between grain orientation and stress concentration factor for creep-fatigue crack initiation is revealed through a sequence of simulation results, followed by the competitive relation. On this basis, a feature region map is constructed to distinguish the factor-dominated crack initiation. Finally, a case study of turbine disk is provided to illustrate the engineering meanings of the dual-scale modelling approach. The link from scientific problem to engineering application for the crack initiation prediction is bridged by the damage mechanics approach, which is also expected to be promoted in many high-temperature components.

在这项工作中，三种双尺度建模方法包括子建模方法、耦合建模方法和全场晶体塑性有限元 (CPFE) 方法，用于蠕变疲劳加载条件下的缺口结构。在综合比较的基础上，确定子建模方法是其中的最优仿真策略。此外，采用子建模方法研究了晶粒取向和应力集中对裂纹萌生的综合影响。在低应力集中系数下，由于晶粒取向分布的影响，裂纹最可能萌生的位置随机位于几何不连续的根部。随着应力集中因子的增加和热点处晶粒数量的减少，通过一系列模拟结果揭示了晶粒取向与应力集中因子之间在蠕变疲劳裂纹萌生中的协同关系，随后是竞争关系。在此基础上，构建了特征区域图来区分因素主导的裂纹萌生。最后，以涡轮盘为例说明双尺度建模方法的工程意义。损伤力学方法将裂纹萌生预测从科学问题到工程应用联系起来，也有望在许多高温部件中得到推广。在此基础上，构建了特征区域图来区分因素主导的裂纹萌生。最后，以涡轮盘为例说明双尺度建模方法的工程意义。损伤力学方法将裂纹萌生预测从科学问题到工程应用联系起来，也有望在许多高温部件中得到推广。在此基础上，构建了特征区域图来区分因素主导的裂纹萌生。最后，以涡轮盘为例说明双尺度建模方法的工程意义。损伤力学方法将裂纹萌生预测从科学问题到工程应用联系起来，也有望在许多高温部件中得到推广。