GOALI/Collaborative Research: Reliable Prediction of Endurance Life of Ultra-High-Strength Aerospace Rolling-Element Bearings

滚动轴承是几乎所有机械中用于转子支撑的关键精密部件。全球每年与轴承相关的收入高达505亿美元。未来对先进飞机发动机，风力涡轮机和高速铁路的高性能转子支撑的需求要求轴承在恶劣的操作条件下存活数千小时，从而存活数十亿次滚动接触疲劳（RCF）循环。具有分级材料性能的新一代高强度轴承钢已被设计用于应对这些挑战。现有的生命预测方法依赖于可追溯到20世纪40年代的经验模型，导致新一代物质的观测和预测生命之间存在很大差异。这个学术与工业联络（GOALI）合作研究项目旨在基于新的实验和计算程序来预测新一代轴承材料的可靠使用寿命和结构完整性，以了解在微观和纳米尺度上由于RCF引起的材料降解。其结果将转化为具有较大经济影响的其他部件的设计，如传动齿轮，凸轮，铁路车轮和轨道，以及制造工具。这项研究的目的是将学术界的注意力重新集中在与制造业相关的研究上，并更好地帮助美国的工业。该项目将有助于教育和培训未来的制造业研究人员和领导者。该合作项目涉及开发一种基于物理的新型材料特定寿命预测模型，该模型基于对从亚微米/纳米到宏观长度尺度的成品和rcf影响材料的局部材料特性的基本理解。该项目将开发：1)作为荷载、温度和RCF循环函数的地下梯度材料响应的可量化措施；2)理解微观结构特征对材料循环响应、合成应力和应变场以及疲劳损伤影响的计算方法；3)基于不断变化的弹塑性地下应力和应变场，改进现有Lundberg-Palmgren经验方法的材料特异性RCF寿命预测方法。在千兆循环中跟踪RCF材料损伤的方法将可用于可靠的寿命预测，这对于未来部件设计的更广泛的摩擦学和异质材料领域的应用具有相当重要的意义。该项目的知识意义包括两个新的贡献：1)它将有助于开发一种新的材料特定的RCF寿命预测模型，特别有利于新轴承材料的加速设计；2)它将产生一种方法来模拟滚动接触中特定循环的材料性能演变，与齿轮、凸轮、铁路车轮和工具的设计直接相关。

Rolling-element bearings are key precision components used for rotor support in nearly all machinery. The annual revenue associated with bearings is a substantial $50.5 billion worldwide. Future demands on high performance rotor support for advanced aircraft engines, wind turbines and high-speed rail require bearings to survive thousands of hours and consequently billions of Rolling Contact Fatigue (RCF) cycles under severe operating conditions. A new generation of high strength bearing steels with graded material properties has been designed to meet these challenges. Existing life prediction methodologies rely on empirical models dating back to the 1940s, resulting in a large discrepancy between observed and predicted life, for the new generation of materials. This Grant Opportunity for Academic Liaison with Industry (GOALI) collaborative researh project aims to predict reliable service life and structural integrity of new generation bearing materials based on novel experimental and computational procedures for understanding material degradation due to RCF at the micro and nanometer scale. The results will translate to the design of other components with large economic impact such as transmission gears, cams, railway wheels and tracks, and manufacturing tooling. This research is an effort to bring back an academic focus to manufacturing-related research to campuses and to better assist US industries. The project will contribute to the education and training of future manufacturing research workforce and leaders.This collaborative GOALI project involves developing a novel physics-based material-specific life prediction model rooted in fundamental understanding of local material properties of as-manufactured and RCF-affected materials from sub-micrometer/nanometer to macroscopic length scales. The project will develop: 1) quantifiable measures for subsurface graded material response as a function of load, temperature and RCF cycles; 2) computational approaches for understanding the influence of microstructural features on the material cyclic response, resultant stress and strain fields, and fatigue damage; and 3) a material-specific RCF life prediction methodology based on enhancements to the existing Lundberg-Palmgren empirical approach by the evolving elastic-plastic subsurface stress and strain fields. Methodologies for tracking RCF material damage in the giga-cycle regime will become available for reliable life prediction, which are of considerable importance with applications to broader areas of tribology and heterogeneous materials for future component design. Intellectual significance of the project comprises of two novel contributions: 1) it will aid development of a new material-specific RCF life prediction model, particularly beneficial to accelerated design of new bearing materials, and 2) it will result in a methodology to model cycle-specific material property evolution in rolling contacts, with direct relevance to design of gears, cams, railway wheels and tooling.