This study is dealing with the effect of the grain size on the fatigue lifetime of metallic components, which is represented in the form of (S-N) Wöhler curves of two different grain sizes. The micro-models containing the microstructures of the two different grain sizes are handled by employing the Finite Element Method (FEM) and the required number of cycles for crack initiation was calculated by using the physically-based Tanaka-Mura model. By implementing the different grain sizes in the micro-model, the effect of the grain size on the fatigue life and especially on the endurance limit, in the form of the S-N_ini diagram, can be obtained.

中文翻译：

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晶粒尺寸对疲劳起始寿命曲线的影响

本研究涉及晶粒尺寸对金属部件疲劳寿命的影响，以两种不同晶粒尺寸的 (SN) Wöhler 曲线形式表示。使用有限元方法 (FEM) 处理包含两种不同晶粒尺寸的微观结构的微观模型，并使用基于物理的 Tanaka-Mura 模型计算裂纹萌生所需的循环次数。通过在微观模型中实现不同的晶粒尺寸，可以以SN _ini图的形式获得晶粒尺寸对疲劳寿命，尤其是对耐久极限的影响。