A General Approach to the Analysis of Fatigue Cracks in Lubricated Contacts

近年来，人们已明显认识到影响最关键组件性能的失效机制的重要性，这些组件经历相互接触的相互作用。特别是，大多数复杂的工程产品，如轴承、燃气轮机叶片/轴、齿轮、铁路、螺栓法兰、汽车发动机等，都离不开接触和摩擦界面。因此，对这些组件的摩擦学性能进行评估（即，如果受到润滑剂、摩擦和磨损的影响，联轴器的材料强度如何）对于任何工业环境都是必须的。让我们以轴承为例。它们是用于减少摩擦和为旋转或线性设备提供负载支持的机械部件。单个轴承故障可能导致数小时的停机时间，包括识别和更换故障部件。因此，世界各地的公司在不同类型的预测性维护技术上花费了大量的资金和资源。这表明，需要对导致这些失败的主要现象进行基础研究。拟议的工作将试图解决在润滑接触存在的情况下材料失效的根本原因。根据一些实验观察、工程实践经验和理论分析结果，流体的作用通常被认为是造成灾难性裂纹扩展的主要因素。将研究接触副的滚动/摩擦引起的裂纹的起源，并研究被认为对裂纹扩展负责的流体/固体相互作用。此外，强大的实验技术将允许监测和测量在滚动接触过程中产生的裂纹内流体的存在以及随后的裂纹扩展到失效。一个适当管理的研究计划将提供有关组件在不同工作条件下受到接触载荷时的性能的宝贵反馈。它将揭示用于改进的信息，以防止将来出现故障。严格确定根本原因可能导致以下改进：(a)更安全(b)改进设计和可靠性(c)提高效率(d)减少维修(e)减少生命周期成本

In recent years there has been noticeable appreciation of the importance of failure mechanisms which affect the performance of the most critical assemblies, whose components undergo mutual contact interactions. In particular, most of the complex engineering products such as bearings, gas turbine blades/shafts, gears, railways, bolted flanges, car engines, etc. could not operate without contact and frictional interfaces. Therefore the assessment of tribological performance (i.e. how the material strength of couplings if affected by the presence lubricants, friction and wear) of these assemblies is a must for any industrial setting.Let us consider bearings as an example application. They are mechanical components used to reduce friction and provide load support for rotary or linear equipment. A single bearing failure can cause hours of downtime, including the identification and replacement of the failed component. For this reason, companies around the world have spent a vast amount of money and resources on different types of predictive maintenance technology. This suggests that fundamental research on the main phenomena responsible for such failures needs to be carried out.The proposed work will attempt to address the root causes of material failures in the presence of lubricated contacts. The role of fluid, according to some experimental observations, experience gathered from engineering practice, and the results of the theoretical analyses, is often regarded as the main contributor to catastrophic crack growth. The origin of cracks induced by the rolling/rubbing of contacting pairs will be studied and the fluid/solid interaction which is deemed as responsible for the propagation of such cracks will be investigated. Furthermore, robust experimental techniques will allow monitoring and measuring the presence of fluid within cracks generated during rolling contacts and subsequent crack growth to failure.A properly managed research programme will provide valuable feedback about how a component performs when subjected to contact loading under different working conditions. It will uncover information for improvements that prevent future failure. Rigorous root cause determination might lead to improvements that yield:(a) Greater safety(b) Improved design and reliability(c) Greater efficiency(d) Reduced maintenance(e) Reduced life-cycle costs