Fretting generates surface damage at the contact interface of components under pressure subjected to small-magnitude, relative oscillatory motion. In the presence of bulk cyclic loading, fretting fatigue occurs, significantly reducing the lifetime of affected components, such as the dovetail joint connections in turbine blades. In this research, the fretting fatigue response of additively manufactured (AM) Ti-6Al-4V parts was studied, focusing on the dovetail geometry. A specialized test setup was developed to evaluate the resistance of the AM material to fretting fatigue conditions and compare its response to its conventionally manufactured counterpart. In parallel, a finite element (FE) model of the testing apparatus was created to provide deeper insights into the stress distribution at the contact interface. Results of the numerical simulations revealed that the most damaging mode of fretting fatigue, known as stick–slip, was achieved, closely resembling the conditions often observed in real-life industrial assemblies. The experimental results demonstrate that the tribomechanical fretting fatigue response of AM-Ti64 aligns with that of the conventionally manufactured material. While AM-Ti64 exhibits better crack propagation resistance, it is more prone to fretting damage. However, the AM material is hindered by near-surface internal defects, such as lack-of-fusion-induced voids and porosities, which form during the manufacturing process. These defects act as stress concentrators, leading to early failures outside the contact zone.

中文翻译：

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研究增材制造的 Ti-6Al-4V 在燕尾榫接头连接中的微动疲劳响应

微动在受到小幅度相对振荡运动的压力下，在部件的接触界面处产生表面损伤。在存在整体循环载荷的情况下，会发生微动疲劳，从而显著缩短受影响部件的使用寿命，例如涡轮叶片中的燕尾榫接头连接。在这项研究中，研究了增材制造 （AM） Ti-6Al-4V 零件的微动疲劳响应，重点是燕尾榫几何形状。开发了一种专门的测试装置来评估增材制造材料对微动疲劳条件的抵抗力，并将其响应与传统制造的同类材料进行比较。同时，创建了测试设备的有限元 （FE） 模型，以更深入地了解接触界面处的应力分布。数值模拟的结果表明，实现了最具破坏性的微动疲劳模式，称为粘滑，与现实生活中的工业组件中经常观察到的情况非常相似。实验结果表明，AM-Ti64 的摩擦机械微动疲劳响应与传统制造的材料一致。虽然 AM-Ti64 表现出更好的抗裂纹扩展性，但它更容易受到微动损伤。然而，增材制造材料受到近表面内部缺陷的阻碍，例如在制造过程中形成的缺乏熔融诱导的空隙和孔隙。这些缺陷充当应力集中器，导致接触区之外的早期失效。