热-力载荷下高速铁路车轮扁疤引起的轮轨冲击力学响应与滚动接触疲劳机理研究

Wheel flat is a main type of damage to induce the possible wheel/rail failure, and it is a significant academic and engineering research issue in the field of high-speed wheel-rail interaction. Considering those service conditions of the wheel-rail system such as low temperature, plastic deformation, fatigue damage, frictional heating and impact loading, based on the experimental investigation, numerical simulation and theoretical analysis, the impact response, damage evolution and rolling contact fatigue of the wheel-rail system with a wheel flat under thermo-mechanical loading will be studied in this proposal. The temperature- and strain rate-dependent dynamic constitutive relationship of wheel/rail materials with different fatigue damage degrees will be proposed, and the influences of train speed, flat length and axle load on the wheel-rail impact response will be discussed. Then an elastic-plastic analysis model for wheel-rail impact induced by a flat will be developed. Subsequently, the competitive relationship between the rolling contact fatigue and wear of the wheel/rail under different impact loadings will be explored, and the corresponding initiation mechanism and propagation regularity will be clarified. Considering synthetically the damage evolution mechanism and regularity of the plastic deformation, rolling contact fatigue and wear, a detecting and evaluating method for service safety of the flated wheel-rail system will be explored. These results can provide valuable technological guidance for the design, assessment and maintenance strategy of the safety of high-speed wheel-rail system.

车轮扁疤是一种诱发轮轨失效的主要损伤形式，是高速铁路轮轨关系研究中亟待解决的学术和工程难点问题。本项目基于高速轮轨系统低温、塑性变形、疲劳损伤、摩擦温升和冲击载荷等服役条件，拟采用实验研究、数值模拟和理论分析相结合的研究手段，研究热-力载荷下含扁疤车轮-轨道系统的冲击力学响应、损伤演化与滚动接触疲劳。建立轮轨材料疲劳损伤、温度和应变率相关的动态本构关系，探讨列车速度、扁疤长度和轴重等关键参量对轮轨冲击响应的影响规律，发展车轮扁疤引起的轮轨冲击的弹塑性理论分析模型，分析不同轮轨冲击载荷下滚动接触疲劳和磨耗之间的竞争性关系，把握不同扁疤长度条件下的轮轨滚动接触疲劳与磨耗萌生机制和发展规律。综合考虑轮轨材料塑性变形、滚动接触疲劳和磨耗等耦合损伤的演变机理与规律性，探索发展含扁疤车轮-轨道系统服役安全的评测方法。为高速轮轨系统的服役安全性设计、评估及维修策略提供技术支持。

车轮踏面缺陷是高速铁路轮轨关系研究中亟待解决的学术和工程难点问题。本项目聚焦于典型的车轮非圆化损伤，围绕“材料本构关系-轮轨冲击响应-损伤演化-滚动接触疲劳”等关键科学问题开展研究。采用试验研究、有限元仿真和理论分析相结合的研究方法，研究了轮轨钢在宽应变率、宽温度范围内的力学性能，揭示了轮轨钢的应变率与温度依赖性及动态变形与断裂机理，发现了D1车轮钢的“第三类应变时效”现象，提出了高速轮轨钢考虑初始等效疲劳损伤的率相关本构模型；发展了三维轮轨滚动接触弹塑性理论分析模型，构建了轮轨滚动接触弹塑性蠕滑力/率映射关系，阐明了轮轨材料应变率效应对轮轨蠕滑特性的影响机制；建立了可考虑应变率效应和温度影响、适用于直道/弯道工况的三维轮轨滚动接触有限元模型，探究了车轮踏面缺陷尺寸、列车速度、轴重和曲率半径等关键参量对轮轨动态响应的影响规律，阐明了应变率效应抑制轮轨塑性变形与热应力劣化轮轨承载能力之间的耦合影响机制；研究了初始等效疲劳损伤对轮轨动态接触行为的影响，揭示了复杂多源条件耦合下的轮轨动力作用机理，阐明了应变率效应和等效疲劳损伤对轮轨接触应力/应变状态的竞争性影响机制；构建了轮轨滚动接触疲劳裂纹萌生和扩展预测有限元模型，探讨了关键参量对裂纹萌生和扩展特性的影响机理与规律，揭示了轮轨滚动接触疲劳与磨耗的竞争性机制；提出了将车轮几何不圆顺转换为轮轨接触位移不平顺的动态有限元仿真方法，系统研究了车轮踏面缺陷引起的轮轨冲击力学响应与损伤演化机理，给出了综合考虑轮缘/轮径磨耗和车轮踏面缺陷的多目标优化镟修策略，发展了基于轮轨动态响应的疲劳可靠性寿命预测方法。研究结果可为高速轮轨系统的服役安全性设计、评估及维修策略提供技术支持。