Chapetti Mirco D, Gubeljak Nenad, Kozak Dražan
Laboratory of Experimental Mechanics, INTEMA, National University of Mar del Plata-CONICET, Av. Colón 10.850, Mar del Plata 7600, Argentina.
Faculty of Mechanical Engineering, University of Maribor, Smetanova ul. 17, 2000 Maribor, Slovenia.
Materials (Basel). 2023 Aug 28;16(17):5874. doi: 10.3390/ma16175874.
In the field of long-life fatigue, predicting fatigue lives and limits for mechanical components is crucial for ensuring reliability and safety. Fracture mechanics tools have enabled the estimation of fatigue lives for components with small cracks or defects. However, when dealing with defects larger than the microstructural characteristic size, estimating the fatigue resistance of a material requires determining the cyclic resistance curve for the defect-free matrix, which depends on knowledge of the material's intrinsic fatigue limit. This study focuses on the experimental evidence regarding the intrinsic fatigue limit and its correlation with naturally nucleated non-propagating cracks. Fracture mechanics models for small crack propagation are introduced, and their disparities and limitations are analyzed. The concept of intrinsic fatigue limit is then introduced and applied to reanalyze a recent publication. Methods for estimating the intrinsic fatigue limit are explored and applied to experimental results reported in the literature. The need to clarify and accurately predict the intrinsic fatigue limit is highlighted in alloys where the processing generates defects larger than the microstructural size of the matrix, as often observed in materials and components produced using additive manufacturing.
在长寿命疲劳领域，预测机械部件的疲劳寿命和极限对于确保可靠性和安全性至关重要。断裂力学工具已能够估算带有小裂纹或缺陷部件的疲劳寿命。然而，当处理大于微观结构特征尺寸的缺陷时，估算材料的抗疲劳性需要确定无缺陷基体的循环阻力曲线，这依赖于对材料固有疲劳极限的了解。本研究聚焦于关于固有疲劳极限及其与自然形成的非扩展裂纹相关性的实验证据。介绍了小裂纹扩展的断裂力学模型，并分析了它们的差异和局限性。接着引入固有疲劳极限的概念并应用于重新分析最近的一篇出版物。探索了估算固有疲劳极限的方法并将其应用于文献报道的实验结果。在合金中，如在使用增材制造生产的材料和部件中经常观察到的那样，加工产生的缺陷大于基体的微观结构尺寸，此时明确并准确预测固有疲劳极限的必要性凸显出来。
