动车组轮轴可靠性试验技术和评价方法研究

The axle-wheel system is an important component of the high-speed trains. Wheel set reliability is not only important to the security of trains running, also plays an important role in guiding the design of high-speed train wheel set. This application will focus on the key scientific problems such as the size effect of the wheel and axle fatigue, speed effects and environmental effects of fatigue and wear, as well as the short fatigue crack formation and expansion. The mechanism of ultra-high cycle fatigue, fretting fatigue, contact fatigue of wheel and axle will be investigated through combination of the actual operation of the axle, full-size sample and the reduced wheel and axle specimen testing. The following objectives will obtained by implement of the application. Main factors affecting the reliability of wheel set will be understood. The evaluation capacity of China''s high-speed Electric Multiple Units （EMU）axle-wheel system reliability integrated materials, components, structure and environmental will be established. The wheel set reliability evaluation specification for high-speed railway in China operating conditions will be formed. The EMU wheel set service safety information database and the reliability evaluation experts system will be built to provide technical support and reliability evaluation for the safe operation and the localization of wheel set system of high-speed EMU in China.

轮轴系统是高速列车的重要构件，轮轴可靠性不仅关系列车运行的安全性，还对高速列车轮轴的设计起到重要指导作用。本申请将围绕轮-轴疲劳特性的尺寸效应、轮轴疲劳和磨损的速度效应、环境效应以及轮、轴疲劳短裂纹的形成、扩展规律和机理等关键科学问题，通过实际运行轮轴的跟踪分析、全尺寸试样及缩比试样相结合的轮轴可靠性实验技术以及轮轴超高周疲劳、微动疲劳、接触疲劳等失效规律和失效机理的研究，弄清影响轮轴可靠性的主要因素；形成我国高速动车组轮轴系统可靠性材料-构件-结构-环境一体化的综合研究、评价能力；建立适合我国高速铁路运行状况的轮轴可靠性评价规范；研发动车组轮轴服役安全信息数据库和可靠性评价专家系统；为我国高速列车轮轴系统安全运行提供保障，为高速动车组轮轴系统国产化提供技术支撑和可靠性评价。

本项目围绕动车组轮轴材料、设计和实验可靠性安全技术研究领域，针对动车组轮轴运用中出现的两种典型科学问题—车轮轮辋疲劳裂纹问题和动车组车轴轴颈旋转弯曲疲劳开展了动车组轮轴可靠性试验技术和评价方法研究，主要研究结论和研究成果如下所述：.探明了车轮踏面浅表层裂纹和轮辋内部裂纹的萌生机理和扩展特点，针对轮辋内部疲劳裂纹形核、扩展微观尺度，建立了夹杂物对轮辋强度影响的仿真模型，分析了夹杂物类型、位置、形状以及聚集状态对轮辋强度的影响规律，应用高速轮轨关系试验台模拟了车轮轮辋裂纹扩展行为。针对轮辋I、II 及复合型裂纹疲劳扩展规律研究，提出了一套系统的轮辋裂纹损伤容限数值仿真方法，研究了轮辋裂纹的扩展模式和扩展规律。.系统测试分析了轴颈表面粗糙度、机械损伤类型及残余应力状态对轴颈疲劳性能的影响趋势和规律，获得了大量科研数据。结合实验室测试和仿真计算，分别以小试样和实物车轴为研究对象，针对轴颈旋转弯曲疲劳短裂纹形核机理及扩展行为开展研究，分析了形核裂纹萌生及扩展特性，分析了轴颈短裂纹和长裂纹扩展规律的差异。在测试材料和实物车轴疲劳极限基础上，完成了小试样与全尺寸车轴旋转弯曲疲劳行为相关性分析。.对影响轮轴可靠性的因素，如尺寸效应、表面状态、夹杂物等进行研究和测试，给出了影响轮轴可靠性共性关键指标评价指导意见；提出了含夹杂物的轮辋可靠性建模和评估方法，完成了夹杂物尺寸、类型对轮辋疲劳可靠性及灵敏度分析；完成了基于可靠性分析的加速实验方法及理论研究，提出了车轮应力谱和等效台架试验载荷、车轴载荷谱的编谱理论，完成了轮轴240万km强化载荷谱编制和台架实验测试。.通过项目研究，基本探明了轮轴典型失效的特点，编写了动车组轮轴疲劳可靠性试验技术和评价准则初稿，该准则可用于动车组轮轴新产品的疲劳可靠性评定、性能验证以及线路服役条件下的性能模拟,对于代替轮轴产品装车考核和缩短新产品研发周期具有积极工程意义。