Interplay of fretting wear, fatigue and damping: Influence of contact shape and mode of loading

微动磨损、疲劳和阻尼的相互作用：接触形状和负载模式的影响

• 批准号: 434193846
• 负责人: Professor Dr. Valentin L. Popov
• 金额: --
• 依托单位: Fachgebiet Systemdynamik und Reibungsphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/434193846?language=en
• 关键词: Interplay; fretting; wear; fatigue; damping

Fretting wear and fretting fatigue represent a considerable and long standing problem in applications using frictional contacts subjected to vibrations as e.g. fretting of tubes in heat exchangers, joints in orthopaedics, or dovetail blade roots of gas turbines. The physical reason for the fretting is partial sliding in the vicinity of boundary of a frictional contact. It is due to the vanishing normal pressure at the contact boundary in contacts with curved surfaces. This partial slip and the resulting fretting wear can only be prevented by using a contact with sharp edges (as e.g. a flat-ended cylinder). However, in this case, both normal and tangential stresses will be singular at the boundary, and the high oscillating stress will lead to fretting fatigue. Thus, applications with frictional contacts under vibrations should find an optimal path between Scylla of fretting wear and Charybdis of fretting fatigue. One way to avoid fretting damage could be the introduction of phase shifts between different oscillation modes which leads to a moving slip zone and may qualitatively change the character of wear and fatigue. Another way could be to completely suppress vibrations. However, in many structures this suppression can only occur due to damping caused by micro slip. Nevertheless, high structural damping due to friction (without damaging the contacting surfaces) can also be a positive constructive goal for itself (as e.g. in space applications).In the present project we study this triad “wear-fatigue-damping” for the fretting contact of steel-on-steel. We will study the transition from fretting wear to fretting fatigue by continually changing the shape from parabolic to flat-ended and by considering the superposition of normal and tangential oscillations with various amplitudes and phase shifts. The intended research work aspires to reduce fretting damages and thereby increase the life span of tribological systems. The project will comprise extensive empiric investigations, ranging from short-term model experiments to very-long-term endurance and fatigue tests. The experimental investigations will be supported by physical models and numerical simulations of the underlying contact mechanics and the governing damage mechanisms.The department "System Dynamics and Friction Physics" of Technische Universität Berlin, where the project is to be carried out, has excellent research experience in the field of tribology and is one of the world's leading institutions in the investigation of dynamic contact problems.

微动磨损和微动疲劳在使用受振动摩擦接触的应用中是一个相当大的和长期存在的问题，例如热交换器中的管，骨科关节或燃气轮机的燕尾叶根的微动。微动的物理原因是摩擦接触边界附近的部分滑动。这是由于与曲面接触时接触边界处的法向压力消失所致。这种局部滑移和由此产生的微动磨损只能通过使用与锋利边缘的接触来防止（例如，平端圆柱体）。然而，在这种情况下，法向应力和切向应力在边界处都是奇异的，高振荡应力会导致微动疲劳。因此，在振动下具有摩擦接触的应用应该在微动磨损的Scylla和微动疲劳的Charybdis之间找到一个最佳路径。避免微动损伤的一种方法可能是在不同的振荡模式之间引入相移，这将导致滑动区移动，并可能定性地改变磨损和疲劳的特性。另一种方法是完全抑制振动。然而，在许多结构中，这种抑制只能由于微滑移引起的阻尼而发生。然而，由于摩擦而产生的高结构阻尼（不损坏接触面）本身也可以是一个积极的建设性目标（例如在空间应用中）。在本项目中，我们研究了钢与钢之间微动接触的“磨损-疲劳-阻尼”三元组合。我们将研究从微动磨损到微动疲劳的转变，通过不断改变形状，从抛物线到平端，并考虑叠加法向和切向振荡的不同幅度和相移。预期的研究工作渴望减少微动损伤，从而增加摩擦学系统的寿命。该项目将包括广泛的实证研究，从短期模型试验到非常长期的耐力和疲劳试验。实验研究将通过物理模型和数值模拟来支持潜在的接触力学和控制损伤机制。该项目将在柏林技术大学Universität的“系统动力学与摩擦物理系”开展，该系在摩擦学领域拥有出色的研究经验，是世界上研究动态接触问题的领先机构之一。