A two-phase approach to estimate fatigue crack initiation and propagation lives of notched structural components
A two-phase approach to estimate fatigue crack initiation and propagation lives of notched structural components
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DOI：
10.1016/j.ijfatigue.2018.06.049
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发表时间：
2018-11-01
影响因子：
6
通讯作者：
Guedes Soares, C.
中科院分区：
文献类型：
--
作者：
Dong, Y.;Garbatov, Y.;Guedes Soares, C.
将缺口结构构件的总疲劳寿命视为裂纹萌生阶段和扩展阶段的总和，提出了两阶段疲劳寿命预测方法。采用局部应变法和基于断裂力学的方法预测了两阶段的寿命。基于Coffin-Manson定律和简单弹塑性断裂力学裂纹扩展规律在低周疲劳状态下的等效性，建立了两相过渡裂纹尺寸对应的应变-寿命曲线。采用包含短裂纹行为的裂纹扩展模型来预测裂纹扩展寿命。在选择与材料平均晶粒尺寸相关的过渡裂纹尺寸时，考虑到应力梯度和微观组织效应，可以在两相中适当地采用所提出的方法。将该方法应用于各种缺口试件的疲劳寿命预测。在评价中考虑了三维效应。预测结果与实验结果吻合得很好。
Total fatigue lives of notched structural components are considered as a summation of crack initiation and propagation phases and a two-phase approach to fatigue life prediction is presented. The local strain approach and fracture mechanics-based approach are used to predict the lives spent in the two phases. A strain-life curve corresponding to the transition crack size where the two phases are divided is formulated based on the equivalence between the Coffin-Manson law and a simple Elastic-Plastic Fracture Mechanics crack growth law in the low cycle fatigue regime. A crack growth model that includes the short crack behaviour is used to predict the crack propagation life. The transition crack size, related to the average grain size of the material, is chosen in such a way that the proposed approach can be appropriately adopted in both phases, considering the stress gradient and microstructure effects. The proposed approach is applied to predict fatigue lives of various notched specimens. The three-dimensional effect is considered in the assessment. The predictions are in good agreement with the experimental results.