极端冰雪条件下高寒动车组制动盘异常磨损的诱发机理与主动预防

Since the running of low-temperature EMU in China, abnormal wear of brake disc caused by ice and snow occurs usually, endangering the safe operation of EMU seriously. Therefore, exploring the inducing mechanism and the active-prevention of abnormal wear has a great significance to further mastering its core technologies as well as to enhance service security of EMU. Based on multi-source information fusion and SDG (Signed Directed Graph) method, the research is to study the relationship between such multi-source information like the environmental, operating and intrinsic parameters and the brake disc abnormal wear. Following the assumption of process as "Turning-quenching- vaporization-cavitation erosion", based on similar equivalence principle, the research is to establish the small scale equivalent fine model of friction pair and the large scale flow field coupling model considering the train’s operating conditions. To explore the dynamic temperature-stress field of the brake disc and the process of its friction-damage, as well as its inducing mechanism of abnormal wear, the “flow-structure-thermal” multi-physics field coupling model is estalished by adopting the time slice segmented approach. Based on this, the project proposes the snow active-removal and prevention strategy of intermission and staggered-action of brake disc/brake pads. Based on reverse engineering and reconstruction method, the control parameters are optimized. Finally, the typical ice-covered abnormal wear accelerated tests, as well as the active control comparative test in the corresponding conditions, are carried out in 1:1 low temperature and wind field. The research results can provide new ideas and the critical basis for the solution of abnormal wear of brake disc caused by ice and snow.

我国高寒动车组开行以来，极端冰雪条件下制动盘异常磨损时有发生，严重影响了列车运行安全，研究其诱发机理与主动预防对进一步掌握其核心技术，提升高寒动车组服役安全能力有重要意义。项目基于多源信息融合与SDG方法研究摩擦副涉及的环境参数、运行参数以及固有参数等多源异构信息与异常磨损间的关联规律。提出磨损破坏遵循“车削-淬火-汽化-气蚀”过程变化的假设，基于等效相似理论建立摩擦副小尺度等效精细模型，以及考虑列车运行环境的流场耦合大尺度模型，采用时间切片分段处理方法进行“流机热”多物理场耦合仿真，再现制动盘瞬态温度-应力场、摩擦损伤等变化过程，探明异常磨损诱发机理。基于此，提出制动盘/闸片间歇错时动作主动除冰雪预防策略，运用反向设计与重构方法优化其控制参数。最后进行1:1低温风场环境下典型覆冰雪异常磨损试验以及相应工况下主动预防对比试验。研究将为冰雪导致制动盘异常磨损的治理提供新的思路和理论依据。

围绕极端冰雪条件下高寒列车制动盘易发生异常磨损影响行车安全的问题，项目在调查我国高寒列车运用基础上，运用多尺度仿真等方法对制动盘异常磨损诱发机理进行系统性研究并提出预防措施，具体来讲：.依据典型高寒列车运行条件等参数，基于多源信息融合与SDG方法，得到表征制动盘异常磨损影响因素：严寒冰雪导致制动摩擦副动作异常，外界硬质颗粒异物或金属磨屑夹在摩擦面间致使列车运行或制动时持续磨削盘面而造成制动盘划伤。.为仿真再现制动盘的动态过程，建立了制动盘置于低温风雪运行环境的流固耦合仿真模型，结果发现车下结构会降低制动盘散热效率；建立了考虑闸片热膨胀变形的摩擦副热-机耦合模型，并与1：1制动台架试验对比，揭示了制动盘热机性能与摩擦副接触面动态规律，结果显示摩擦副未覆冰、制动初速350km/h时盘面最大热应力约800MPa，极易发生热疲劳裂纹损伤。为此，进一步建立了覆冰摩擦副力耦合模型，仿真表明冰杂质致使盘表面最大应力有超过材料屈服极限现象，对照低温风雪模拟下制动盘磨损试验，结果发现硬质颗粒物是造成盘面划伤主要原因。因此，进一步建立了摩擦界面微小磨粒磨损精细化模型，研究了33种不同工况下制动盘损伤形态，结果发现低速、高压的尖端磨粒磨损是制动盘损伤最严重工况，磨粒损伤是覆冰工况下制动盘损伤主要成因。.结合仿真与高寒制动盘损伤形式，提出了改善制动盘热机性能和降低磨粒磨损深度的主动预防策略：（1）间歇式制动控制策略以期降低热疲劳裂纹损伤可能，以制动初速度350km/h工况为例，最大热应力可降低139MPa；（2）阶段式制动控制策略以有效控制运行速度与制动压力动作过程，仿真显示可改善制动盘最大磨粒磨损深度近40%。.综上，项目建立了“列车-车下流场-摩擦副-摩擦边界-磨粒”多尺度多介质仿真模型，通过分段时序处理方法，再现了摩擦副动态作用与磨损破坏过程，提出了相应的预防策略，研究方法丰富了高寒制动盘异常磨损过程分析理论，研究结果为其服役运用提供了依据参考。