高速列车车轮型面多目标优化研究

对于动车组车轮磨耗引起的动力学性能降低问题,车轮型面优化是一个很好的解决方案。采用旋转压缩微调法（Rotary-scaling fine-tuning method,RSFT）进行型面生成;建立某型动车组车辆动力学模型,采用该模型计算相应的优化目标和约束条件;利用径向基神经网络-粒子群（Radial-based neural network-particle swarm optimization,RBF-PSO）算法优化出最优廓形。通过对比优化前后车轮型面的动力学性能和磨耗性能,可以发现：优化后车轮型面临界速度为424.6 km/h,增大10.2%;横向平稳性和垂向平稳性指标整体减小,同时提高了曲线通过时的安全性指标,脱轨系数、倾覆系数和轮轴横向力都进一步减小。优化后车轮型面接触点分布相对更加均匀,等效锥度减小。同时优化后车轮型面有效减小车轮磨耗深度,并减小了轮缘根部磨耗,车轮最大磨耗深度减小9.8%。     

Theoretical cross-wind speed against rail vehicle derailment considering the cross-running wind of trains and the dynamic wheel-rail effects

In this paper, a theoretical formula was proposed that predicts the derailment index due to a cross wind applied to a rail vehicle considering the cross running wind condition of two running trains as well as the dynamic wheel-rail effects. The recently developed derailment theory on a wheelset was applied to this new cross wind derailment formula. Contrary to the conventional formulas, this new derailment formula was derived considering a dynamic derailment coefficient (Q/P) under normal running, the friction coefficient between the wheel and the rail, the wheel load variation, the cross running wind effects, and the cross wind. Using this proposed formula, the derailment pattern and the critical cross wind speed of derailment could be predicted for various cross running wind conditions of two running trains. Finally, for some typical examples, the results of this proposed formula were compared and verified with those of the conventional formulas and the numerical simulation of multi-body dynamics software, Recurdyn.     

高速列车车轮多边形对齿轮箱疲劳寿命的影响

车轮多边形是高速列车运行过程中常见的磨耗现象,该现象使轮轨作用力增大,齿轮箱持续异常振动,并会影响其疲劳寿命。为研究高速列车车轮多边形对齿轮箱疲劳寿命的影响,建立了含有齿轮箱支撑轴承的驱动系统和柔性齿轮箱的刚柔耦合整车动力学模型,采用数值仿真分析方法,通过分析不同车轮多边形幅值下轮轨垂向力和齿轮箱垂向振动加速度确定极端工况,对该工况下的齿轮箱进行应力分析并确定危险点,进而分析这些点的疲劳寿命。研究发现:列车在350 km/h三阶0.1 mm车轮多边形极端工况时,轮轨垂向力及齿轮箱垂向加速度明显增大,齿轮箱剧烈振动,此时齿轮箱多处出现应力集中,存在多个危险点。其中齿轮箱输出轴轴承端支撑筋处应力最大,该危险点疲劳寿命只能达到256万km,远小于1200万km的正常寿命。因此,在高速列车实际运营中要高度重视车轮多边形对齿轮箱疲劳寿命带来的影响,可通过车轮镟修来降低车轮多边形对齿轮箱疲劳寿命的影响。     

轮缘润滑对列车曲线通过动态响应影响分析*

为研究轮缘润滑对重载列车曲线通过性能的影响,建立重载列车-轨道三维耦合动力学模型,该模型主要包含重载列车系统模型、有砟轨道系统模型和考虑多点接触和复杂接触状态的轮轨滚动接触模型。利用该模型对比分析惰行工况和驱动工况下,轮缘润滑对重载列车曲线通过时轮轨动态相互作用的影响。研究结果表明：轮缘润滑对机车曲线通过时的轮轨动力相互作用影响显著,在机车轮对通过小半径圆曲线过程中,当存在轮缘润滑时,外侧轮缘位置处的轮轨纵向蠕滑力明显较无轮缘润滑时明显降低,轮对导向能力削弱;在惰行和牵引工况下通过圆曲线时,存在轮缘润滑的轮对冲角均明显增大;轮缘润滑对重载列车钩缓系统响应影响不大。     

A new derailment coefficient considering dynamic and geometrical effects of a single wheelset

A new derailment coefficient of a single wheelset was theoretically developed by considering the dynamic and geometric effects from lateral acceleration and gyro factors as well as mechanical factors like flange angle, frictional coefficient, wheel-unloading, wheel radius, track gauge and position of axle bearings. This new derailment coefficient (lateral force over vertical wheel load, P/Q) can predict the commencement of various derailments, such as wheel climbing and lifting types, roll-over types and their combined types. In addition, this derailment coefficient can analyze the various dynamic and geometrical effects of a wheelset, which are not considered in the conventional derailment coefficients of Nadal’s and Weinstock’s formulas. This derailment coefficient was verified by comparing its theoretical anticipations of several examples with numerical simulation results using a commercial dynamic S/W, RecurDyn.     

组合轮径差对地铁车辆动力学性能的影响

为了研究各种轮径差组合形式对地铁车辆动力学性能的影响,基于车辆系统动力学和赫兹非线性接触理论,建立地铁动车非线性动力学模型,分析各种轮径差组合工况下地铁车辆的临界速度、平稳性、安全性和磨耗功率及其变化规律。结果表明:在多种轮径差组合工况下,轮径差增大会使地铁车辆的临界速度有较大幅度降低,会使地铁车辆的横向平稳性和磨耗功率明显增大;轮径差对地铁车辆的垂向平稳性、轮轴横向力、轮轨垂向力、脱轨系数和轮重减载率影响较小;通过左、右曲线时,轮径差对磨耗功率增幅的影响存在差异,但变化规律一致。     

高速铁路车轮扁疤激扰响应的小波包分解与限值研究

扁疤是轨道交通车辆车轮踏面的典型故障之一,其对于列车运行的平稳性和安全性有很大影响。目前尚未对不同速度下的扁疤限值制定统一的标准。本文对动力学仿真计算得到的轮轨力随机响应采用一种全局性的小波包分解处理方法,提取轮轨力随机信号的能量系数作为评判指标,从能量特征的角度研究了不同速度等级下的车轮扁疤安全限值,并与在时域信号中提取轮轨力随机响应的最大值、均值和脉冲因子作为评判扁疤安全限值的方法相比较。结果表明：小波包能量系数从全局性角度描述轮轨力特性,节点能量系数呈线性规律,可作为高速铁路车轮扁疤安全限值的评判指标。研究得出当列车速度在150～250 km/h范围内,扁疤长度应控制在30 mm以内;当列车速度在250～350 km/h范围内,扁疤长度应控制在25 mm以内。     

Assessment of running safety of railway vehicles using multibody dynamics

An analysis model for multibody systems was developed to assess the running safety of the Saemaeul train passing through curves. Sensitivity analyses based on the variation of parameters related to derailments were conducted using this model and the ADAMS/Rail software package. These analyses showed that the derailment coefficient and the unload ratio of the right wheel were higher than that of the left wheel at low speed, but lower at high speed. The derailment coefficient and the unload ratio increased as the curve radius decreased. The derailment coefficient increased but there was no change in the unload ratio as the length of transition curves increased. The derailment coefficient and the unload rate increased in proportion to the increase in track cant.     

基于SIMPACK的扁疤车轮轮轨冲击力学特性分析

为研究高速列车车轮多处扁疤引起的动力学问题,建立了CRH2型动车组的车辆-轨道动力学模型及车轮扁疤模型。采用变轮径扁疤模拟法,分析单处和两处扁疤的车轮引起的轮轨冲击响应,确定车轮两处扁疤时的扁疤长度、车速及扁疤间夹角变化对轮轨冲击的影响,进而确定CRH2型动车组安全运行时车轮扁疤限值,为高速动车组列车的行车安全提供了依据。     

强风雨环境下高速列车运行安全特性

为确保高速列车在强风雨环境下安全运行,结合EULER-LAGRANGE方法和计算多体动力学方法,系统地研究风雨环境下高速列车的气动特性及运行安全特性。基于非球形雨滴,建立高速列车空气动力学计算模型,并验证计算模型的准确性,进而计算强风雨环境下作用于高速列车的气动载荷。建立高速列车车辆系统动力学模型,计算强风雨载荷作用下的高速列车运行安全特性。研究结果表明,在不同风速下,高速列车的侧力、升力、侧滚力矩及摇头力矩均随降雨强度的增加而增大,且与降雨强度近似成线性关系,对于点头力矩,当风速较小时,点头力矩随降雨强度的增加而增大,而当风速较大时,点头力矩随降雨强度的增加而减小。与单纯的强风环境相比,降雨使得高速列车的运行安全特性进一步恶化,在不同风速下,高速列车脱轨系数、轮重减载率、倾覆系数及轮轴横向力均随降雨强度的增加而增大,特别是当风速接近于临界风速时,降雨对高速列车运行安全特性的影响显著。当降雨强度为500 mm/h时,由不同运行安全指标确定的高速列车安全运行的临界风速降低2.3~4.2 m/s。研究结果可为高速列车在风雨环境下的安全限速提供参考。     

轮对扁疤对高速列车转向架振动特性的影响

为准确预测高速列车轮对擦伤对车辆性能的影响,基于车轨耦合动力学和非赫兹接触理论,对新旧两种轮对扁疤的几何外形进行数值描述,建立了考虑轮对扁疤的高速列车动力学模型,分析了轮对扁疤激扰对车辆走行部的影响。结果表明,旧扁疤对走行部冲击要大于新扁疤,随着扁疤尺寸的增大,走行部各部件受到的冲击载荷与振动加速度逐渐增大;随着速度增大,轮轨间垂向冲击先增大、后减少;当扁疤长度为10mm,速度为100km/h 时,轮轨垂向力达到最大值;随着速度增加,走行部簧下部件与簧上部件的振动特性差异不断加大。以轮轨垂向力为判断标准时,轮对扁疤尺寸应限制在30mm以内。     

轮轨接触界面摩擦管理研究进展

列车向着高速与重载方向迅速发展,显著加剧了轮轨接触界面间的损伤。通过在轮轨接触界面进行摩擦管理能够有效地降低轮轨之间的磨损、显著提高列车的运行安全性以及降低运营成本。对轮轨接触界面摩擦管理研究现状进行综述,并介绍轮轨界面摩擦控制对轮轨作用力、黏着、磨耗、滚动接触疲劳以及振动与噪声影响的研究进展;展望了轮轨接触界面摩擦管理未来研究方向,即应针对不同应用环境和接触部位,研发合理的摩擦控制材料,以克服摩擦管理过程中对轮轨损伤及使用局限性等问题;应探究车轮踏面/轨顶面和轮缘/轨距面摩擦控制方式,严格控制摩擦材料喷涂量使两接触面不相互干扰,优化改进轮轨接触界面摩擦管理的最佳应用参数;应研发环境友好型的轮缘/轨距面润滑剂与车轮踏面/轨顶面摩擦控制剂,稳定调控轮轨接触界面的黏着特性。     

车间纵向减振器失效对列车动力学性能影响

为了研究车间纵向减振器失效对动车组动力学性能的影响,基于SIMPACK建立某高速动车组动力学模型;分析车间纵向减振器在失效工况下对整车动力学性能影响,有助于解决高速动车组车间纵向减振器异响及异常问题。研究结果表明:车间纵向减振器失效对稳定性影响不大,对垂向平稳性影响也较小,横向平稳性和舒适性有明显恶化;中间车横向平稳性和舒适性恶化情况比两端车严重,两端车横向平稳性指标最大增加率为5.4%,舒适性指标最大增加率约25%,中间车横向平稳性指标最大增加率约10%,舒适性指标最大增加率约45%;轮轴横向力、轮轨垂向力、脱轨系数及轮重减载率等安全性指标受其影响较小。     

Dynamic analysis of a train-bridge system under multi-support seismic excitations

A numerical solution for the dynamic responses of a train-bridge interaction system subjected to multi-support seismic loads was studied. The train vehicle was modeled by the rigid-body dynamics method, and the bridge was modeled by the finite element method. The vertical and lateral wheel-rail interaction forces were defined according to the wheel-rail corresponding assumption and the simplified Kalker creep theory. Three-dimensional seismic accelerations were incorporated using the large mass method. In a case study, the dynamic responses were simulated for a high-speed train traversing a steel truss cable-stayed bridge with different seismic intensities and different train speeds, and train safety was evaluated.     

An easy instrument and a methodology for the monitoring and the diagnosis of a rail

Nowadays, there are no systematic methodologies for evaluating life assessment of the rail, and few systems provide the measures of vertical and lateral forces that train exchanges with the rail. These systems are quite expensive and require the substitution of a portion of the track. In the present paper is presented a simple transducer (MPQY) for measuring, at the same time, the vertical and lateral forces. The easy installation and use of this instrument are its main characteristics. It is sufficient to put it in a hole, made in the rail web in the concurrence of the drilling axis, and connect it to the transmitting station for measuring for each convoy the vertical and lateral forces induced by each wheel. It can be also used for analysing speed and mass of trains and the specific derailment ratio. In addition, by using a damage model, it is possible to estimate the residual life of a rail. In order to do this, a linear model of rolling contact fatigue damage is implemented and tested with same experimental acquisitions. Another application of this transducer can be identified in the variation of the mechanical behaviour of ballast. In fact, by using the information coming from the MPQY and comparing it with the flexural moment measurement, it is possible to evaluate the variation of ballast behaviour with respect to time and set new parameters for ballast maintenance and train safety.     

The effect of rubber contact on the fretting fatigue strength of railway wheel tire

The cause of the ICE train derailment, which occurred in 1998 at Eschede, was fatigue failure originating on the inside of the wheel tire. Rubber-sprung resilient wheels were used for the trailer cars. The wheel tire is mounted on the wheel disc. Thirty-four rubber pads were arranged between the wheel disc and the wheel tire. It was postulated that fretting fatigue between the rubber block and the inner side of the tire might have an influence on the initiation of the incipient crack. In order to clarify the influence of the rubber contact on the fatigue strength of the tire, fretting fatigue experiments under rubber contact conditions were performed. During the fundamental fretting fatigue test using bridge pads and small size carbon steel specimens, no typical fretting damage such as fretting wear and minute cracks were observed due to contact of the rubber. Stress conditions of the rubber-sprung wheel under vertical and lateral wheel loads were evaluated by a three-dimensional elastic stress analysis. Since the rubber is a super-elastic material, the Mooney-Rivlin model was used in the FEM calculation. It was found that the wheel tire is subjected to a cyclic stress during one revolution of the wheel and the maximum stress occurred at the center of the inner surface of the tire where the fatigue crack initiated. Fatigue strength of the wheel tire was determined by the rotating bending fatigue testing of specimens taken from the tire. It was found that the tire with an 862 mm diameter at a wheel load of 80 kN had a safety factor more than 3.5 from a fatigue limit diagram with a failure probability of 0.01. To confirm the fretting damage under the rubber contact and the result of the fatigue strength evaluation, fatigue tests of a full size wheel were made. After 20 million cycles at the wheel load of 280 kN, which was just below the endurance limit estimated by the endurance limit diagram, no fretting damage and no fatigue cracks were observed. The wheel was, however, fractured at 1.56 million cycles under the maximum load of 308 kN, which was just above the endurance limit. The estimation of the safety factor of 3.5 estimated from the endurance diagram was confirmed by the full size fatigue testing. It was concluded that there was no effect of fretting due to the rubber contact on the fatigue strength of the rubber-sprung single-ring railway wheel.     

高寒地区列车遭遇暖湿气流后轮轨界面黏着与车轮损伤响应行为研究

利用轮轨滚动试验机模拟了-40℃环境工况下不同湿度（10%～99%）暖湿气流对高速轮轨界面黏着与车轮表面损伤的响应行为。低温环境下轮轨界面遭遇暖湿气流时,黏着系数会迅速减小,且随着气流湿度的增大,黏着系数减小的幅度和恢复时间均增加;同时,与未遭遇暖湿的轮轨界面相比,黏着系数、磨损量、塑性变形层厚度均明显增大,且随着气流湿度的增大,平均黏着系数减小,磨损量和塑性变形层厚度增大。在低温无湿气作用工况下,车轮磨损机制主要为疲劳磨损,剖面裂纹以表层裂纹为主;低温间歇暖湿气流作用下,车轮磨损机制主要以氧化磨损和黏着磨损为主,磨损表面出现氧化磨屑堆积而成的第三体层,剖面裂纹出现了多层裂纹和次表层裂纹。低温环境下,暖湿气流对列车的轮轨界面黏着和车轮损伤影响显著,主要体现在黏着系数的瞬时大幅减小以及车轮材料更为严重的磨耗和疲劳损伤。因此,高寒地区应特别注意暖湿气流对列车轮轨损伤和黏着的影响,以保证列车的安全运行。     

接触刚度对高速列车轮轨接触动力学时变特性的影响及其机制

以CRH3型高速列车头车与标准CHN60型轨道为研究对象,利用动力学软件RecurDyn建立车辆-轨道耦合动力学模型;采用弹簧阻尼模型定义轮轨接触关系,跟踪检测服役列车不同运行里程下的车轮粗糙度,根据相关文献的轮轨接触刚度计算结果,对高速轮轨滚动接触动力学性能进行研究,并取该头车的后转向架二位轮对处结果进行数据分析。计算结果表明:随着高速列车运行里程的增加,车轮表面粗糙度减小,使得轮轨接触刚度增大;轮轨横向力随着运行里程的增加先减小后增大,其频率主要分布在10 Hz以下的低频段;轮轨垂向力随着运行里程的增加而增加,并在5、10、28 Hz附近有比较明显的主频率段;轮轨纵向力主要由切向蠕滑力的纵向分量构成,与轮轨垂向力在时域分布和频域分布上均非常相似。     

车辆脱轨安全限值的调整与改进建议

针对国家标准GB5599－85评判车辆脱轨所存在的问题，提出采用车轮抬升量作为车轮脱轨的直接判据。运用车辆－轨道耦合学理论，对我国主型货车C62A分别以单轮对－轨道耦合模型和整车－轨道耦合模型为仿真计算对象，研究了脱轨系数超限时间与车轮抬升量的关系。并对国家标准GB5599－85中关于脱轨系数和轮重减载率的规定作了调整和改进，建议将脱轨系数大于目标值1．0的持续作用时间小于0．035s作为车辆脱轨的安全限值。     

基于ADAMS的铁道车辆脱轨后动态行为分析

采用ADAMS仿真软件建立了脱轨前的车辆系统动力学轮轨接触模型和脱轨后的多刚体接触碰撞模型来研究制动盘对铁道车辆脱轨后运行行为的影响。为了真实地模拟车辆脱轨后的运行行为和接触力,接触模型包含车轮-轨道板和制动盘-钢轨两对接触,设置了合理的接触参数并使用了真实的三维几何外形和非线性接触算法。仿真结果表明,制动盘在车辆脱轨后与钢轨发生了连续的接触碰撞,可以抑制脱轨车辆进一步脱离线路。