Fretting fatigue often occurs in contact couples subjected to both bulk oscillatory loads and normal loads, which accelerates the initiation and propagation of fatigue cracks. This study explores the multiaxial fretting fatigue behaviour of 35CrMoA steel with different contact stresses under diamond and square loading paths by experimental methods. From experimental results, the fracture mechanisms with the increase of contact stress have been summarized by combining the analysis of macrorupture and microrupture surface. The strain response behaviour, characteristics of fretting region and crack propagation direction are also analysed and concluded considering the influence of loading path and contact stress in this paper, which have been rarely mentioned in the previous literature. In addition, debris composition of stick and slip regions is investigated as well.

中文翻译：

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接触应力对多轴非比例路径下35CrMoA钢微动疲劳行为的影响

微动疲劳常发生在承受大的振动载荷和法向载荷的接触偶中，这会加速疲劳裂纹的产生和传播。本研究通过实验方法探索了在金刚石和正方形载荷路径下不同接触应力的35CrMoA钢的多轴微动疲劳行为。从实验结果出发，结合宏观破裂和微观破裂表面分析，总结了随着接触应力增加而产生的破裂机理。本文还考虑了加载路径和接触应力的影响，分析了应变响应行为，微动区域特征和裂纹扩展方向，并在以往的文献中很少提及。此外，