30t轴重重载货车轮轨接触几何关系及动态匹配关系

针对我国30t轴重的重载货车及线路条件,以改善轮轨匹配特性为目的,对LM车轮踏面与不同类型钢轨匹配时的轮轨接触几何关系和轮轨动态相互作用进行了分析,并在此基础上研究了钢轨轨底坡对轮轨接触几何关系及车辆动态曲线通过性能的影响。研究结果表明:相对于CHN60和USA68钢轨,CHN75钢轨在轮对横移较小时可提供较低的等效锥度,轮对横移量超过4 mm后,等效锥度逐渐增大,能在保证车辆运动稳定性的同时利于其通过曲线线路,且采用CHN75钢轨可以降低轨道结构的受力。重载线路在使用CHN75钢轨,轨底坡设为1/40时,踏面等效锥度及货车曲线通过性能要优于1/20和1/30的轨底坡设置。     

车轮踏面异常磨耗对轮轨关系影响分析

利用多体动力学分析软件SIMPACK建立了地铁车辆动力学分析模型,选取异常磨耗后的几种典型钢轨型面,通过考虑轨道表面不平顺和轮轨蠕滑等非线性因素,研究了车轮踏面异常磨耗对轮轨接触行为和动力学行为的影响。结果表明：车轮踏面异常磨耗影响轮轨接触点的分布,从而进一步影响车辆的动力学性能;轻微磨耗后的踏面轮轨型面匹配较好,轮轨动力学行为相比原始轮轨型面有所改善;车轮踏面异常磨耗后的车辆动力学性能大大降低,尤其是在通过小半径曲线时,车辆动力学性能较差;车轮踏面两沟槽磨耗对车辆动力学行为影响明显大于一沟槽磨耗的车轮踏面。     

表面粗糙度对轮轨黏着特性影响

水油介质下极易发生轮轨低黏着现象,结合轮轨黏着试验和根据二维滚动接触理论和部分弹流润滑理论建立轮轨黏着数值仿真模型,给出了水油介质下轮轨表面粗糙度对轮轨黏着系数和增黏的影响规律,验证了数值仿真模型的有效性.结果表明:水介质下随蠕滑率增加黏着系数呈先快速增加后小幅减小并稳定的变化;水、油介质下随表面粗糙度增加轮轨黏着系数呈增加趋势;水介质下轮轨表面粗糙度从1μm提高到50μm,黏着系数增加126.5%,油介质下轮轨表面粗糙度从5μm提高到20μm,黏着系数增加61.4%.     

重载机车在不同牵引工况下的轮轨匹配分析

重载机车轴重增大及速度提高带来了严重的轮轨磨耗问题.针对机车在不同牵引工况下的轮轨型面匹配情况,应用轮轨型面测量仪实测机车车轮型面数据,将标准与磨耗后机车车轮型面分别和标准75 kg/m钢轨型面在对中位置匹配,建立机车轮对-钢轨三维有限元模型,并进行接触计算分析,得出如下结论:车轮踏面磨耗使轮轨间的Mises应力减小,其中标准型面的最大Mises应力点出现在轮轨表面下2~3 mm处,磨耗型面的最大Mises应力点更接近轮轨表面;牵引力使车轮的等效应力点较钢轨上的应力点位置出现纵向偏移,且随着牵引力的增加,纵向偏移量越大;车轮的踏面磨耗使轮轨接触斑中心更接近钢轨内侧轨距角;施加不同牵引工况时的轮轨横向切应力几乎不变;施加相同牵引工况时,车轮型面磨耗1 mm的轮轨纵向切应力大于标准型面,而车轮型面磨耗2 mm的轮轨纵向切应力小于标准型面.     

轨道参数对重载铁路钢轨焊缝区域轮轨动力作用的影响

基于车辆-轨道耦合动力学理论和30t轴重货车-轨道垂向耦合动力学模型,计算了30t轴重货车通过钢轨焊缝不平顺区域时,轨道参数对轮轨作用的影响。结果表明:随着轨下支承刚度和轨下支承阻尼的增大,轮轨作用加剧;随着轨枕间距的增大,轮轨作用将有所减小;随着轨枕质量的增大,轮轨作用将略微增大,轨枕振动将明显降低。     

油介质下轮轨粘着特性数值分析-研究生论坛

基于二维滚动接触理论和部分弹流理论,建立了微凸体接触情况下的稳态部分弹流数值模型,运用多重网格法对油介质工况下的轮轨黏着特性进行数值仿真研究。利用所建立的数值仿真模型研究了轮轨接触压力分布情况,分析了滚动速度、载荷、轮轨表面粗糙度等参数对轮轨黏着特性的影响。结果表明:油介质条件下轮轨接触区的宽度比干态下要宽,是干态下接触区宽度的1.5倍左右;油介质下的轮轨黏着系数明显小于干态下的黏着系数;轮轨黏着系数随着速度的增加逐渐减小,随接触压力的增加而降低,随轮轨表面粗糙度的增加而增大。     

考虑轮轨多点接触关系的车轨系统地震响应分析

为研究地震作用下轮轨多点接触关系及其对车轨系统地震响应的影响,本文基于虚拟渗透理论分析了轮轨多点接触的几何关系,采用修正的Kik-Piotrowski方法和Kalker线性理论求解轮轨接触力,并建立了地震作用下考虑轮轨多点接触关系的列车-无砟轨道系统模型;以某高速铁路为对象,研究了车轨系统的地震响应及列车的行车安全性。研究结果表明：地震作用下轮轨之间会出现2点接触情况,次接触斑对轮轨接触行为具有重要影响;轮轨多点接触关系对地震作用下的轮轴横向力和脱轨系数具有重要影响,不考虑该多点接触关系会低估列车的行车安全性;车轮抬升量对地震动强度不是特别敏感。     

轨道不平顺与轮轨匹配对地铁车辆晃动的影响

为了综合分析轨道不平顺与轮轨匹配对地铁车辆晃动的影响机理,采用动力学试验与数值仿真相结合的方法展开研究.测试车辆晃动的横向振动加速度、轮轨廓形及轨道不平顺,掌握车辆晃动、不同轮轨匹配特征,分析轨道不平顺及轮轨匹配对车辆晃动的影响.结果表明：当地铁运行线路存在周期性轨道不平顺时,将严重影响车辆平稳性;不同轮轨型面匹配引起的转向架蛇行运动频率与轨道激励频率、车体滚摆模态频率的接近程度不同,是导致车辆平稳性存在差异的原因.及时处理轨道周期性不平顺,合理控制轮轨型面匹配的等效锥度能够有效改善地铁车辆的运行品质.     

直线滚动导轨磨损退化对导轨参数的影响

为了研究直线滚动导轨磨损退化对导轨各参数的影响,考虑了每个滚珠的受力、变形和初始预紧力,推导和计算了与磨损退化有关的刚度退化模型、预紧力退化模型、接触角变化模型、摩擦力和摩擦因数模型、最大蠕滑率和临界载荷模型.直线滚动导轨滚珠与滚道的磨损伴随着直线导轨的刚度和预紧力产生退化.同时,上排和下排的滚珠接触角、临界载荷、摩擦因数、摩擦力、最大蠕滑率等参数也发生变化.以上参数对滚动导轨的性能具有重要意义,但这些参数很难直接通过试验测量得到.以国产某型号滚珠直线导轨为研究对象,对所建立的各模型进行仿真分析.结果表明:直线滚动导轨磨损退化对导轨各参数均有不同程度的影响,通过测量直线滚动导轨轨道的磨损可以有效预测导轨各参数的变化规律.     

CRH2型动车组轮轨接触计算及车轮强度CAE分析

为了分析计算CRH2型动车组在垂向静载荷作用下的车轮最大计算载荷,并确定轮轨接触斑的几何形状参数,利用SolidWorks软件模拟出车轮及静载下的轮轨接触有限元模型,并于Simulation中通过提取分割几何线的方法进行有限元图解分析。结果表明,垂向静载条件下车轮一周踏面横向位移呈三角函数曲线变化趋势,计算模拟仿真结果可用于横向稳定性计算、车轮动态横向响应曲线计算等,还可用于轨道几何参数和轮轨外形的合理选择。     

Development of a vehicle–track interaction model to predict the vibratory benefits of rail grinding in the time domain

Imperfections in the wheel–rail contact are one of the main sources of generation of railway vibrations. Consequently, it is essential to take expensive corrective maintenance measures, the results of which may be unknown. In order to assess the effectiveness of these measures, this paper develops a vehicle–track interaction model in the time domain of a curved track with presence of rail corrugation on the inner rail. To characterize the behavior of the track, a numerical finite element model is developed using ANSYS software, while the behavior of the vehicle is characterized by a unidirectional model of two masses developed with VAMPIRE PRO software. The overloads obtained with the dynamic model are applied to the numerical model and then, the vibrational response of the track is obtained. Results are validated with real data and used to assess the effectiveness of rail grinding in the reduction of wheel–rail forces and the vibration generation phenomenon.

     

Rail fatigue crack propagation in high-speed wheel/rail rolling contact

Railway Engineering Science - To study the wheel/rail rolling contact fatigue of high-speed trains, we obtain the distribution of contact forces between wheel and rail by introducing the...     

地铁弯道曲率半径对钢轨磨损的影响

根据赫兹接触理论,在JD—1型轮轨模拟试验机上通过改变钢轨曲率半径研究了曲线半径对地铁钢轨磨损的影响。实验结果表明:随着曲率半径的减小,钢轨磨损量增大,磨损深度和宽度均有所增加;钢轨曲率半径较小时,轮轨间存在蠕滑行为,钢轨承受的横向水平力和摩擦力均增大,这将导致钢轨接触面产生严重的塑性变形和表面硬化。     

Numerical simulation of wheel wear evolution for heavy haul railway

The prediction of the wheel wear is a fundamental problem in heavy haul railway. A numerical methodology is introduced to simulate the wheel wear evolution of heavy haul freight car. The methodology includes the spatial coupling dynamics of vehicle and track, the three-dimensional rolling contact analysis of wheel-rail, the Specht's material wear model, and the strategy for reproducing the actual operation conditions of railway. The freight vehicle is treated as a full 3D rigid multi-body model. Every component is built detailedly and various contact interactions between parts are accurately simulated, taking into account the real clearances. The wheel-rail rolling contact calculation is carried out based on Hertz's theory and Kalker's FASTSIM algorithm. The track model is built based on field measurements. The material loss due to wear is evaluated according to the Specht's model in which the wear coefficient varies with the wear intensity. In order to exactly reproduce the actual operating conditions of railway,dynamic simulations are performed separately for all possible track conditions and running velocities in each iterative step.Dimensionless weight coefficients are introduced that determine the ratios of different cases and are obtained through site survey. For the wheel profile updating, an adaptive step strategy based on the wear depth is introduced, which can effectively improve the reliability and stability of numerical calculation. At last, the wear evolution laws are studied by the numerical model for different wheels of heavy haul freight vehicle running in curves. The results show that the wear of the front wheelset is more serious than that of the rear wheelset for one bogie, and the difference is more obvious for the outer wheels. The wear of the outer wheels is severer than that of the inner wheels. The wear of outer wheels mainly distributes near the flange and the root; while the wear of inner wheels mainly distributes around the nominal rolling circle. For the outer wheel of front wheelset of each bogie, the development of wear is gradually concentrated on the flange and the developing speed increases continually with the increase of traveled distance.     

独立车轮与钢轨接触问题的研究

应用有限元参数二次规划法建立了独立车轮与钢轨接触的三维计算模型,通过分析不同踏面、不同相对位置的轮轨接触,得出了轮轨接触斑形状和面积、接触力的变化规律,并且对比不同踏面在减缓磨耗方面的特点.同时建立了磨耗后的轮轨接触模型,分别研究直线段和曲线段轮轨配合接触问题,总结了不同模型的接触斑面积、形状、位置,以及接触力分布和等效应力的变化规律.结果表明磨耗后的轮轨配合与其它模型相比接触斑面积最大,轮轨匹配相对较好.     

浮置式轨道在实测轮轨力作用下的动力响应

针对现有的三种浮置式轨道结构建立三维有限元模型,通过大型有限元软件ANSYS对三者施加一试验中实测的轮轨力数据,分别得到三种浮置式轨道结构的动态响应,而后再做以比较,定性的得到三种浮置式轨道结构的减振降噪效果以及各自固有频率的范围,从而提出在实际工程应用中不同工况条件下浮置式轨道结构合理的选型、应用以及搭配方案,并为浮置式轨道的其他动力特性的分析提供了一个关键的动态理论参数.     

Wear characteristics and prediction of wheel profiles in high-speed trains

Wheel/rail relationship is a fundamental problem of railway system. Wear of wheel profiles has great effect on vehicle performance. Thus, it is important not just for the analysis of wear characteristics but for its prediction. Actual wheel profiles of the high-speed trains on service were measured in the high-speed line and the wear characteristics were analyzed which came to the following results. The wear location was centralized from-15 mm to 25 mm. The maximum wear value appeared at the area of 5 mm from tread center far from wheel flange and it was less than 1.5 mm. Then, wheel wear was fitted to get the polynomial functions on different locations and operation mileages. A binary numerical prediction model was raised to predict wheel wear. The prediction model was proved by vehicle system dynamics and wheel/rail contact geometry. The results show that the prediction model can reflect wear characteristics of measured profiles and vehicle performances.     

轮轨横向接触系统的自激振动分析

为了研究轮轨接触过程中发生的自激振动现象对轮轨曲线啸叫噪声的影响,建立了轮轨横向接触系统的单自由度动力学方程,采用基于De Beer模型的改进的新型摩擦系数模型计算了轮轨接触面上的摩擦力变化,用相平面法分析了动、静摩擦系数以及横向蠕滑率对该自激振动系统的稳定性影响.计算结果表明：不稳定的轮轨自激振动会激发车轮的若干模态...