极端复杂环境所致电弧侵蚀对弓网接触的动态耦合损伤及失效机理研究

The pantograph and catenary system is a key collector which is directly exposed to the atmospheric environment. The arc will produced and burn the carbon skateboard and contact line while under the influence of ice climate due to the lack of flow. In this project, the action mechanism of cold, ice-coated contact line and alternately changing environment on contact damage of pantograph and catenary was studied combined with dynamic coupling mechanics analysis of pantograph-catenary contact. Firstly, the difference of contact damage between pantograph and catenary under different working conditions (contact load, slip velocity, excitation frequency, current) is analyzed according to the results of dynamic mechanical analysis to pantograph and catenary. Then the arc mechanism of the interface under the condition of ice coating is studied, and the influence of arc ablation on the microstructure and tribological behavior of the interface is discussed. The dynamic coupling effect of arc erosion and mechanical wear on the damage surface between pantograph and catenary is analyzed. Finally, the physical model of wear interface and particle formation by considering the environmental influence coefficient is established through the simulation of extremely and complex environment, the transfer function between the physical model and the increment of dynamic contact resistance is discussed. The prediction function model of dynamic contact resistance is established to analyze the failure mechanism of contact between pantograph and catenary. This subject is based on the problems related to the planning and construction of Sichuan-Tibet railway and provides some theoretical reference for improving the ability of pantograph and catenary system to deal with snow and ice disasters.

弓网系统是列车直接暴露在大气环境中的重要集电元件，受到高寒、雨雪等气候的影响，将导致受电弓取流不畅而产生电弧，甚至发生燃弧并灼烧碳滑板和接触线。本项目在弓网接触动态耦合力学分析的基础上，研究高寒、接触线覆冰及交替变化环境对弓网接触损伤的作用机制。首先结合弓网动态力学分析结果，分析不同工况（接触载荷、滑移速度、激振频率、电流）下弓网接触损伤差异；接着研究接触网覆冰条件下接触界面的燃弧机理，探讨电弧烧蚀对接触界面微观组织形貌和摩擦化学行为的影响，重点分析电弧侵蚀与机械磨耗对弓网接触损伤的动态耦合作用；最后通过极端复杂环境的模拟，构建考虑环境影响系数的弓网接触界面磨耗和磨粒形成物理模型，探讨此物理模型与动态接触电阻增量的传递函数。建立动态接触电阻的预测函数模型，以分析弓网接触失效机理。本课题立足于国家关于川藏铁路规划建设的相关问题，为提高弓网系统应对冰雪灾害的能力提供一定理论参考。

项目通过模拟弓网系统在极端复杂工况下进行载流摩擦磨损试验，揭示了不同工况下的接触线覆冰所致电弧侵蚀对弓网界面的损伤特性和失效机理，主要获得以下成果：.1、实现了低温环境下碳滑板和接触线的载流摩擦磨损过程的模拟，通过设计和改造试验设备，研发了一种可模拟接触线覆冰以及电弧侵蚀试验的载流摩擦磨损试验设备，可以高度模拟极端复杂工况下的弓网载流动态服役过程。.2、研究发现：不同的铜/石墨含量对于接触副之间的载流摩擦磨损性能影响显著，铜含量的增加有助于形成有效的导电网络结构，从而增强了接触副的导电性能，但是降低了接触副的耐磨性，增加石墨含量有利于提高接触副的耐磨性，但是增加了接触电阻和界面温升。.3、研究发现：低温环境下不同的接触线材料对弓网系统的载流摩擦磨损性能影响显著，通过对比发现，Cr-Zr-Cu合金/碳滑板的载流摩擦磨损性能最优，低温环境下接触线表面形成覆冰层，在载流磨损试验初期将引起强烈电弧侵蚀，此时瞬时电弧侵蚀会导致覆冰层迅速熔化，使碳滑板接触线变成直接接触，因此在随后的磨损过程中电弧逐渐消失；.4、研究发现：在低温环境下，不同工况下的电弧侵蚀对弓网接触界面的损伤影响显著。纯碳滑板/浸铜滑板在经过不同的电弧侵蚀之后，界面发生了恶化，纯碳滑板主要是熔融层、侵蚀坑、裂纹，碳滑板表面主要是瘤状物堆积、电弧侵蚀坑和不规则氧化层。弓网之间的接触电阻随着侵蚀时间的增加而上升，摩擦系数随着电弧侵蚀时间的增加而发生剧烈波动；纯碳滑板在较短的电弧侵蚀时间时，其抵抗电弧侵蚀的能力要优于浸铜滑板，然而当侵蚀时间增加到60s时，纯碳滑板的抗电弧侵蚀能力要低于浸铜滑板。.5、研究发现：在常温下，弓网之间的接触电阻随着侵蚀电流的增加而开始发生剧烈的不规则波动，而摩擦系数则随着时间的增加而上升。电弧侵蚀瞬间的放电现象和瞬时温升是导致碳滑板和接触线异常损伤的主要因素。随着电流增加，碳刷/摩擦盘的磨损机制由黏着磨损转变成磨粒磨损。