高速动车组车轮低温服役失效机理及可靠性

The wheels of high speed motor train units (HSMUs) in service are subjected to complex random dynamic loads interactive with impact loads. To meet with optimal service function, the special technology of rolling formation plus local heat treatment makes the wheel structure with a significant character of gradient properties (GPs). The intrinsic phenomena of low temperature (LT) embitterment for metal materials bring a great of risk to anti-disaster by fatigue fracture of the wheel at an out of control. Taking into account of the three elements of LT, impact loading, and structural constraints (SCs) with GPs, a series of fatigue and fracture tests will be performed to reveal the embitterment mechanisms by the three elements. Key affecting factors are expected to be taken and then their affecting laws should be established. Finally, assessment methods for service reliability and safty of the wheel at LT environment will be proposed on a basis of the primary works, i.e. formation of the LT reliability property data of wheel material, simulations of service stressing spectrum and crack growth driving force spectrum, and the regularization to modifying the material properties to structural local properties. Present study may play important academic roles to ensure service safety of HSMUs and the wheels with super long life, high reliability, and high steady properties in service at LT environment.

高速动车组车轮的服役载荷具有复杂随机动载交织冲击载荷的特点；为满足最佳车轮服役功能要求，特殊的“滚压成型+局部热处理”制造工艺使车轮结构具有梯度性能特征；更重要的是，这些要素与固有的金属材料低温致脆现象结合，使预防其低温环境服役时发生不可控制疲劳断裂的任务显得异常重要和艰巨。考虑低温、冲击载荷和梯度性能三要素，完成典型动车组车轮材料与结构效应试样的一系列疲劳断裂试验，揭示材料低温、冲击载荷影响和结构尺度三要素影响的机理；把握关键影响要素，发展三要素相关的低温影响规律性模型；在试验获得车轮材料低温疲劳可靠性数据，建立车轮关键部位应力谱与裂纹扩展驱动力谱计算方法的基础上，发展高速动车组车轮低温服役可靠性及安全性的评价方法。对保证列车低温服役安全，实现车轮长寿命、高可靠性和高稳定性目标，具有重要的科学指导作用。

按规划开展了动车组车轮低温服役条件、 车轮材料低温服役失效机制及规律性和动车组车轮低温服役可靠性评价及材料低温质量评价准则研究. 取得了四方面进展:.(1) 建立了工程材料低温高周疲劳试验系统与测试方法，保证了低温环境疲劳试验的可靠性;.(2) 按规划完成了典型动车组车轮服役磨耗规律、车轮踏面损伤及动力学条件和环境+机械载荷服役应力条件研究，建立了系统性分析计算方法；.(3) 完成了动车组车轮材料低温疲劳行为车轮材料低温疲劳行为机制与规律性研究，揭示了温度对疲劳裂纹萌生寿命、裂纹扩展影响的机制及规律性，揭示了不同于常温的特点与规律性，说明了必须以低温疲劳性能为依据，才能保证车轮服役的可靠性与安全性；.(4) 建立了低温动车组车轮低温服役可靠性评价及材料低温质量评价的系统性方法。.本项目研究为开展生产条件下车轮低温服役可靠性与安全性管理规则研究提供了基础。