高速列车轮轨滚动接触损伤的多因素竞争机理研究

With the ripid development of high-speed railway in our countary, some important mechanical problems needs to be sloved in wheel/rail rolling contact. The wheel/rail rolling contact problem is very important. In wheel/rail rolling contact when the wheel rolling at a high speed, the distribution of contact force plays a key role on the contact fatigue and wear of the rail. It will be developed that the effective wheel/rail rolling contact theory for high-speed train. It will be simulated numerically that the dynamic process of wheel/rail rolling contact while the high-speed train moves in different states. The mutil-scale fracture model will be established for understanding the mechanism of rail damage of contact fatigue and wear. It will be explored that the multivariate competition mechanism of wheel/rail rolling contact fatigue, wear and other damage. The damage cumulative amount of wear and fatigue wll be obtained. It will be explored that the relationship between the distribution of contact force and the damage suach as contact fatigue, abrasion and chap on wheel/rail contact surfaces. Through the monitoring of the typical places of high-speed railway, it will be obtained that monitoring data such as the rail wear, micro-crack initiation and propagation, etc. The monitoring data will be compared with the results from mechanical theory to demonstrate the correctness independently and to ensure the reliability of the results. According to the damage cumulative amount of wear and fatigue, the evaluation indicators will be established for the track diseases such as contact fatigue and wear. To lay the theoretical basis of evaluation methods for the wheel/rail contact diseases. It would be developed that a reasonable track grinding cycle to ensure the safety and economy of high-speed railway. The reasonable suggestions will be given for improving the tread of rail and wheel of high-speed railway.

轮轨高速滚动接触问题是我国轮轨高速中的重要力学问题，轮轨间的高速滚动接触作用力分布形式对轮轨的接触疲劳与磨耗具有决定性的作用。本研究将发展行之有效的轮轨高速滚动接触理论，建立接触作用力分布理论公式；研究高速列车各种运行状态下的滚动接触过程；构建高速轮轨接触疲劳与磨损等轮轨病害形成机理的多尺度断裂力学理论模型，研究高速轮轨滚动接触磨耗与接触疲劳等损伤的多因素竞争机理，获取宏观裂纹扩展及磨耗的累计量；探索轮轨表面磨损过程中的接触疲劳、磨耗、龟裂等损伤与高速滚动接触作用力分布之间的关系；并通过对高铁典型路段的监测，获取轨道磨损、微裂纹萌生及扩展等监测数据；将监测数据与力学理论结果进行独立的对比论证，确保结果的可靠性。根据宏观的轮轨损伤累计量，建立高效的轮轨接触病害评估指标，为轮轨接触病害的评估方法奠定理论依据；制定合理的轨道打磨周期，确保高铁运营的安全性和经济性，为高铁轮轨的改进提供合理化建议。

轮轨高速滚动接触问题是我国高速铁路中的重要力学问题，本研究主要对具有平整接触表面的轮轨高速滚动接触力学理论、接触作用力造成的钢轨表面磨耗和疲劳的细微观力学机理进行研究。具体研究工作及成果如下：. 1）考虑应变率、惯性力、塑性应变累积等，发展了高速轮轨接触理论，实现了轮轨三维高速滚动接触过程的模拟，获得了不同速度下轮轨接触作用力的分布；. 2）基于细微观的断裂力学模型，在高速滚动接触作用力作用下，研究了钢轨表面的龟裂、疲劳裂纹扩展与分叉等宏观损伤与高速滚动接触作用力分布等参数之间的定量关系。同时基于剪切塑性应变累积判据，研究了钢轨表面的磨耗，并对钢轨表面接触疲劳裂纹的扩展与磨耗之间的竞争关系进行了定量描述；. 3）进行了高铁铁路典型段的监测和室内试验，通过选取的典型高铁线路段，进行一个打磨周期内的细致监测，探测轨道的表面磨耗、表面剥离、裂纹的萌生及扩展进行跟踪监测，获取高铁的第一手监测数据。同时对钢轨材料的室内疲劳试验研究，并通过电镜实验研究了疲劳裂纹的形成及其扩展特征。. 4）通过优化对比，分析研究了不同的钢轨顶面半径、形状等情况下，钢轨表面的损伤情况、轮轨磨耗与疲劳累计量等，对具有良好的抗磨耗与耐接触疲劳的轮轨踏面形状进行了探索。结果表明，列车车轮的轮重和滚动速度对接触疲劳与磨耗具有最直接的作用，轮重越大，接触疲劳越严重；速度越大，磨耗与疲劳都会出现快速增加。最有效的方式是减少轮重，或增大接触面积以减少接触作用力峰值；研究成果为高铁轮轨的改进提供合理化建议，助推高铁发展。. 在本项目资助下的研究成果，在重要国内外期刊如Engineering Fracture Mechanics、Theoretical and Applied Fracture Mechanics等,已出版的科技期刊论文共计21篇（均已注明本项目资助），其中SCI收录的英文期刊论文10篇，EI收录的中文期刊论文3篇，其它中文核心期刊论文6篇，研究成果具有重要的科学意义和学术影响，达到了预期研究目标和指标。