重载列车闸瓦制动力不均衡分布状态下轮轨非线性耦合振动及其运行安全性研究

The brake shoe unit is a widely used braking mode in the railway vehicles. With the operation of long heavy-haul train, the problems such as the asymmetric wear of brake shoe, the deformation of brake beam and partial wear of wheel profile, have been increasingly prominent. The induced nonuniform braking forces acting on wheels seriously deteriorate the wheel-rail running conditions, which intensifies the wheel-rail slip and the train-track coupled dynamic effects. And also the great safety risk to train operation is brought. This project proposes to focus on the 10000t and above heavy-haul train. By applying the theoretical analysis and numerical simulation methods, the heavy-haul train-track coupled dynamic model in three-dimension is established, in which the nonlinear factors of nonuniform brake shoe forces, hysteresis characteristics of draft gear and wheel-rail contact relation are considered. From the perspective of system dynamics, the wheel-rail nonlinear coupling vibration and running safety of heavy-haul train are investigated. The core problems of wheel-rail interaction mechanism, dynamic process and nonlinear coupling vibration characteristics are verified. The influence of nonuniform braking forces on train running safety is revealed. Based on the train dynamic performance, the control limit of non-uniformity for braking forces is put forward. The research achievements will be helpful to improve the theoretical study level of train dynamics, and provide the theoretical foundation and technical support for the running safety and the maintenance of heavy-haul train.

闸瓦制动是铁路车辆广泛采用的制动方式，随着长大重载列车的开行，闸瓦不均匀磨耗、制动梁变形、车轮偏磨等问题日益突出，由此引发的车轮间不均匀分布制动力（同一节车各车轮制动力不同）严重恶化了轮轨运行条件，加剧了轮轨界面的滑动和列车-轨道的动力耦合效应，给运行安全性带来了极大隐患。本项目拟针对万t及以上编组重载列车，运用理论分析、数值仿真相结合的方法，建立考虑不均匀闸瓦制动力、缓冲器迟滞特性、轮轨关系等非线性因素的重载列车/轨道三维耦合动力学模型，从系统动力学角度开展闸瓦制动力不均匀分布状态下重载列车轮轨非线性耦合振动特性及其运行安全性研究，探明轮轨相互作用机制、动力过程和非线性耦合振动特性等核心问题，揭示不均匀制动力对列车运行安全性的影响规律，并基于列车动态性能提出闸瓦制动力不均匀程度的控制限度。研究成果有助于提升我国列车动力学理论研究水平，为保障列车安全运营和检修维护提供理论依据和技术支撑。

闸瓦制动故障是重载列车中普遍且频繁出现的故障形式，其直接后果是导致闸瓦制动力在不同车轮上的不均衡分布，在加剧轮轨异常磨耗、提高运营成本的同时也给列车安全运行构成了潜在威胁。鉴于此，本项目围绕重载列车非线性动力学建模、不均衡闸瓦制动力作用机制、不均衡制动条件下轮轨动力学特性及运行安全性等关键科学问题开展了深入研究。发展了考虑不均衡闸瓦制动力的重载列车—轨道耦合动力学模型建模新方法与仿真求解技术，发现了不均衡闸瓦制动力作用在转向架对称轮对却会引起轮对的非对称运动现象，特别是制动故障出现于一位轮对时影响最显著，引发轮对横移量与冲角的急剧增大，不均衡闸瓦力矩与一系摇头力矩则共同决定了转向架这一特有的运动学规律。探明了不均衡制动力作用下轮轨接触几何、切向力传递过程和非线性耦合振动等本质特征，给出了制动力不均衡程度、作用位置等因素对列车行为、轮轨耦合振动及动力作用的影响规律和影响程度，获得了复杂线路上重载列车不均衡制动过程中轮轨运行安全性基本特征和发展规律。不均衡制动主要影响列车的横向动力作用，也极大增加了轮轨滑行风险，纯粹因闸瓦失效引起的轮轨横向力可增大4~10kN，轮轨接触应力增大200~400Mpa，但在不平顺激扰下不均衡闸瓦制动力可引起重载机车轮缘接触和轮轨横向冲击振动，速度越高影响越明显，受此影响轮轨横向力可瞬态增大数十千牛，接近甚至超过要求的安全限值。综合考虑列车运行动力学品质，提出了重载列车的制动初速安全域、不均衡制动力的安全控制域和轮轨防滑控制域。此外，课题组开展了重载列车车轮型面、多边形演化的现场跟踪测试，以及动态性能测试，探索了制动过程中重载机车的振动特性、车轮型面状态和车轮伤损关系，提出了车轮镟修建议。项目研究成果为科学认识闸瓦制动故障状态下的轮轨动力学行为提供了有效的研究途径，为重载列车基础制动装置的养护维修提供了理论支撑和应用参考。