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。全球与轴承相关的年收入高达505亿美元。未来对先进航空发动机、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运行条件下能够承受数千小时的工作时间，从而承受数十亿次的滚动接触疲劳（RCF）循环。新一代具有梯度材料性能的高强度轴承钢就是为了应对这些挑战而设计的。现有的寿命预测方法依赖于可追溯到20世纪40年代的经验模型，导致新一代材料的观测寿命和预测寿命之间存在很大差异。这个学术与工业联络（GOALI）合作研究项目的资助机会旨在预测新一代轴承材料的可靠使用寿命和结构完整性，其基础是新的实验和计算程序，用于理解由于RCF在微米和纳米尺度上的材料退化。其结果将转化为具有巨大经济影响的其他组件的设计，例如传动齿轮，凸轮，铁路车轮和轨道以及制造工具。这项研究是为了把学术重点带回到校园的制造业相关研究，并更好地帮助美国工业。该项目将有助于教育和培训未来的制造业研究队伍和领导者。这个合作GOALI项目涉及开发一种新的基于物理的材料特定寿命预测模型，该模型植根于对从亚微米/纳米到宏观长度尺度的制造和RCF影响材料的局部材料特性的基本理解。该项目将开发：1）作为载荷、温度和RCF循环函数的次表面梯度材料响应的可量化测量; 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的影响的计算方法;以及3）基于改进现有Lundberg-Palmgren经验方法的材料特定RCF寿命预测方法，塑性次表层应力应变场用于跟踪在千兆周期制度的RCF材料损伤的方法将成为可靠的寿命预测，这是相当重要的摩擦学和异质材料的未来组件设计的更广泛的领域的应用程序。该项目的知识意义包括两个新的贡献：1）它将有助于开发新的材料特定的RCF寿命预测模型，特别有利于新轴承材料的加速设计，以及2）它将导致一种方法来模拟滚动接触中特定循环的材料特性演变，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.