Abstract Small fatigue crack initiation behaviour in a series of specimens containing different sizes of micro-notch has been observed through RepliSet system during interrupted low cycle fatigue tests. From the replicating observations, very initial single crack or multiple cracks near the micro-notch area can be captured. Since then, the crack initiation life for each specimen can be determined. Computationally, a numerical procedure with a combination of crystal plasticity theory and finite element implementation has been constructed for predicting small fatigue crack initiation life as well as identifying the crack initiation sites near the micro-notches. With the help of fatigue indicator parameter represented by accumulated plastic slip, the predicted numbers of cycles for the submodels with various micro-notch sizes agreed with the experimental ones. In addition, the simulation results can successfully reveal the mechanism in crack initiation sites. The stress concentration effect was found to be responsible for corner crack initiation, while the combined effects of stress concentration and grain orientation around micro-notch area showed great influence on edge crack initiation.

中文翻译：

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镍基合金 GH4169 中微缺口对小疲劳裂纹萌生行为的影响：实验和模拟

摘要 在间断低周疲劳试验中，通过RepliSet系统观察了一系列含有不同尺寸微缺口的试样的小疲劳裂纹萌生行为。从复制观察中，可以捕获微缺口区域附近的非常初始的单个裂纹或多个裂纹。从那时起，可以确定每个试样的裂纹萌生寿命。在计算上，已经构建了结合晶体塑性理论和有限元实现的数值程序，用于预测小疲劳裂纹萌生寿命以及识别微缺口附近的裂纹萌生点。借助以累积塑性滑移为代表的疲劳指标参数，具有各种微缺口尺寸的子模型的预测周期数与实验一致。此外，模拟结果可以成功地揭示裂纹萌生部位的机理。发现应力集中效应是角部裂纹萌生的原因，而微缺口区域周围的应力集中和晶粒取向的综合效应对边缘裂纹的萌生有很大影响。