中国轨道交通轮轨滚动接触疲劳研究进展

系统阐述了轮轨滚动接触疲劳损伤的分类、萌生机理、影响因素、引发后果及常用萌生预测模型等，总结了其复杂性的根源; 梳理了中国轨道交通系统近年来发生的各种轮轨滚动接触疲劳的相关研究成果，分别总结了高速铁路、普速铁路和地铁等系统轮轨滚动接触疲劳的基本特征、萌生机理及治理措施等; 展示了在局部和连续型滚动接触疲劳研究中，现场跟踪测试、现场试样失效分析、试验台试验、数值模拟及线路试验等研究方法的系统化应用及重要结果; 讨论了不同轨道交通系统滚动接触疲劳差异的根本原因及滚动接触疲劳各影响因素的相对重要性，并从现场治理和机理研究2个方面提出了展望。研究结果表明:高速动车组轮轨局部型滚动接触疲劳(月牙形裂纹)对运营安全的威胁可控，其重要源头之一是硌伤; 过大的接触应力和蠕滑率是引发轮轨连续型滚动接触疲劳的关键，其根本原因包括小半径曲线、轮轨失形、轮轨廓形与轨道曲线设计不合理、大坡度与起伏坡度、低黏着与增黏、频繁启停及轨道安装误差等，近10年来开始大量使用的大功率电力机车在复杂条件线路运行时，呈现的严重车轮滚动接触疲劳是上述影响因素综合作用的集中体现; 可行的滚动接触疲劳防治措施包括避免或及时修复严重硌伤、优化曲线段轮轨廓形匹配、优化轮轨镟修/打磨策略、加装或优化车轮研磨子、机车车辆定期调头运行、优化机车电气补偿与牵引制动控制、使用优质增黏砂、优化踏面制动和及时维护轨道与列车关键部件等，不同轮轨系统可根据其特点酌情选用; 从现场防治角度，应建立轮轨滚动接触疲劳的精确预测模型，并依此实现不同服役条件下的滚动接触疲劳无限和有限寿命设计及最佳轮轨维修策略制定; 从疲劳机理角度，应重点研究疲劳裂纹萌生的微观裂纹扩展机制和磨耗影响机制。 

Research progress on wheel/rail rolling contact fatigue of rail transit in China

The wheel/rail rolling contact fatigue was systematically explained in terms of its classification, initiation mechanisms, influencing factors, consequences, as well as commonly used initiation prediction models, and the source of complexity in wheel/rail rolling contact fatigue was summarized. Related research results of wheel/rail rolling contact fatigue in China Rail Transit System in recent years were summarized. The basic characteristics, initiation mechanisms as well as countermeasures in high-speed railway, traditional railway, and metro systems were summarized, respectively. The systematic use of research approaches such as the field monitoring, failure analysis of field samples, test rig, numerical simulation, and on-line test for studying local and continuous wheel/rail rolling contact fatigue were described, together with their important results. Root causes for differences between different rail transit systems in terms of wheel/rail rolling contact fatigue and the relative importances of these factors were discussed. Finally, suggestions were provided for future studies on practical countermeasures and initiation mechanisms. Research result shows that the wheel/rail local rolling contact fatigue (crescent crack) in high-speed EMU poses controllable threats to the operation safety, and is most often caused by indentations. Excessive contact stress and creepage are critical factors causing the continuous wheel/rail rolling contact fatigue, its root causes include the sharp curve, wheel/rail profile deterioration, inappropriate designs of contact profile and track curve, steep and undulating slope, low adhesion and adhesion enhancement, frequent start and stop, and track mounting error. The severe rolling contact fatigue observed on wheels of high-power electric locomotives widely used in recent decade operating in complex conditions, is the joint manifestation of the comprehensive effect of these factors. Feasible countermeasures for the rolling contact fatigue include the prevention or timely repair of severe indentations, improving wheel and rail profile compatibility in curved sections, optimizing wheel turning and rail grinding strategies, installing or improving the wheel tread cleaner, rolling stocks turn-around operating periodically, improving the electric compensation and traction/braking control in locomotives, using high quality sands for adhesion enhancement, improving the tread braking, and timely repair of key components on tracks and trains. The appropriate countermeasures may be selected according to the characteristics of each wheel-rail system. Relating to the field countermeasure, accurate rolling contact fatigue prediction models should be developed to facilitate rolling contact fatigue infinite- and finite-life designs and the determination of optimal wheel-rail maintenance strategies for different running conditions. Relating to damage mechanisms, future studies should be focused on the microcrack propagation mechanism and the influencing mechanism of wear during the fatigue-crack initiation stage. 1 tab, 42 figs, 150 refs.