Parametric analysis of wheel wear in high-speed vehicles

In order to reduce the wheel profile wear of highspeed trains and extend the service life of wheels, a dynamic model for a high-speed vehicle was set up, in which the wheelset was regarded as flexible body, and the actual measured track irregularities and line conditions were considered. The wear depth of the wheel profile was calculated by the well-known Archard wear law. Through this model, the influence of the wheel profile, primary suspension stiffness, track gage, and rail cant on the wear of wheel profile were studied through multiple iterafive calculations. Numerical simulation results show that the type XP55 wheel profile has the smallest cumulative wear depth, and the type LM wheel profile has the largest wear depth. To reduce the wear of the wheel profile, the equivalent conicity of the wheel should not be too large or too small. On the other hand, a small primary vertical stiffness, a track gage around 1,435-1,438 mm, and a rail cant around 1：35-1：40 are beneficial for dynamic performance improvement and wheel wear alleviation.     

An experimental study of the effect of low-noise wheels in reducing noise and vibration

Wheel/rail interaction is a major source of railway noise. A low-noise wheel structure is developed and its effect on noise reduction is investigated. This low-noise wheel employs a rubber material inserted into the steel rim or mounted on the wheel surface. The low-noise wheel has low stiffness and a high-damping ratio compared to a solid wheel. Measurement shows that it reduces rolling and squealing. It turns out that a subway line with the proposed wheel could reduce its interior noise level by 4–5 dB(A) and vehicle vibration level by 7–8 dB. While the proposed structure seems promising in noise reduction for railway vehicles, the endurance and cost effectiveness of the low-noise wheel are yet to be verified.     

常见机车车轴实物对比试块的新应用

介绍利用目前现有的几种常见机车车轴实物对比试块,校验DF8B(滚抱)和DF7G型内燃机车分体轮、SS6B型电力机车整体轮、8K型机车轮对的车轴齿轮座镶入部横波探伤灵敏度的方法,以实现齿轮座镶入部和内侧卸荷槽的全面扫查。     

铁道车辆轮重测定仪检定装置的研制

为满足铁路货场铁路车辆轮重测定仪的现场检测与维修工作,研制了体积小、重量轻、结构简单的LJ-B型铁路车辆轮重测定仪检定装置。从研制目标、系统结构与原理、研制方案和技术难点及实际运用情况等方面,详细介绍LJ-B型铁路车辆轮重测定仪检定装置。     

CRH2010A综合检测车测力车轮与钢轨滚动接触弹塑性分析

运用非线性有限元分析软件ABAQUS,考虑通过直线、曲线线路和道岔3种工况,建立CRH2010A综合检测车的测力车轮与钢轨的三维滚动接触有限元模型,进行不同工况下测力车轮与钢轨的滚动接触特性及车轮辐板和轴毂的受力分析。结果表明:测力车轮的滚动接触特性与动车车轮相似;通过直线线路且轮对横移量为8mm时,产生轮缘效应,车轮磨损加剧;通过曲线线路时,左侧车轮与钢轨出现两点接触中心区;通过道岔时,左侧车轮与长心轨均发生塑性变形,车轮和钢轨的磨耗加剧;轴毂的过盈连接对轮轨接触特性的影响,远小于其对轴毂连接区域和辐板加工区域应力的影响;在这3种工况下测力车轮均满足静强度要求。     

列车提速对线路的动力影响研究与对策

列车提速是我国铁路实施的具有战略意义的重大决策。由于提速是在既有线眩进行的，提速后机车车辆对线路结构的动力影响将不可避免地增强，给轨道结构强度和线路日常养护维修工作带来不利影响、文中运用车辆一轨道耦合动力学理论，以及车轮擦伤对线路的动力影响等，进行了较细致的分析研究，在此基础上提出了解决这些问题的基本对策。     

The effect of wheel set gyroscopic action on the hunting stability of high-speed trains

This study explores the effects of wheel set gyroscopic action on hunting stability by calculating linear and nonlinear critical speeds. First, a dynamic model for a high-speed vehicle with 23 degrees of freedom is developed by considering wheel set gyroscopic action. The linear and nonlinear critical speeds are calculated by eigenvalue analysis and drawing a bifurcation map, respectively. Two computer programs for linear and nonlinear stability analysis are developed. Second, based on an actual high-speed vehicle in China, the effects of wheel set gyroscopic action on hunting stability are quantitatively investigated using computer simulation. Furthermore, the difference between the effects of gyroscopic moments about the x-axis and z-axis is discussed. The results show that the moment about the x-axis is harmful to hunting stability, but the moment about the z-axis is beneficial to hunting stability. However, the integrated effect of these two moments can enhance the critical speeds and suppress the hunting motion.     

New methodology for fast prediction of wheel wear evolution

In railway applications wear prediction in the wheel–rail interface is a fundamental matter in order to study problems such as wheel lifespan and the evolution of vehicle dynamic characteristic with time. However, one of the principal drawbacks of the existing methodologies for calculating the wear evolution is the computational cost. This paper proposes a new wear prediction methodology with a reduced computational cost. This methodology is based on two main steps: the first one is the substitution of the calculations over the whole network by the calculation of the contact conditions in certain characteristic point from whose result the wheel wear evolution can be inferred. The second one is the substitution of the dynamic calculation (time integration calculations) by the quasi-static calculation (the solution of the quasi-static situation of a vehicle at a certain point which is the same that neglecting the acceleration terms in the dynamic equations). These simplifications allow a significant reduction of computational cost to be obtained while maintaining an acceptable level of accuracy (error order of 5–10%). Several case studies are analysed along the paper with the objective of assessing the proposed methodology. The results obtained in the case studies allow concluding that the proposed methodology is valid for an arbitrary vehicle running through an arbitrary track layout.     

Further study on the wheel–rail impact response induced by a single wheel flat: the coupling effect of strain rate and thermal stress

A comprehensive dynamic finite-element simulation method was proposed to study the wheel–rail impact response induced by a single wheel flat based on a 3-D rolling contact model, where the influences of the structural inertia, strain rate effect of wheel–rail materials and thermal stress due to the wheel–rail sliding friction were considered. Four different initial conditions (i.e. pure mechanical loading plus rate-independent, pure mechanical loading plus rate-dependent, thermo-mechanical loading plus rate-independent, and thermo-mechanical loading plus rate-dependent) were involved into explore the corresponding impact responses in term of the vertical impact force, von-Mises equivalent stress, equivalent plastic strain and shear stress. Influences of train speed, flat length and axle load on the flat-induced wheel–rail impact response were discussed, respectively. The results indicate that the maximum thermal stresses are occurred on the tread of the wheel and on the top surface of the middle rail; the strain rate hardening effect contributes to elevate the von-Mises equivalent stress and restrain the plastic deformation; and the initial thermal stress due to the sliding friction will aggravate the plastic deformation of wheel and rail. Besides, the wheel–rail impact responses (i.e. impact force, von-Mises equivalent stress, equivalent plastic strain, and XY shear stress) induced by a flat are sensitive to the train speed, flat length and axle load.     

不同摩擦系数条件下的轮轨滚动接触特性分析

以直径为860 mm的LMA踏面轮对和60 kg.m-1钢轨为例,采用有限元软件ABAQUS建立三维轮轨滚动接触有限元模型,利用集群逻辑结构的并行计算平台求解该模型,并对不同摩擦系数下轮轨滚动接触特性进行分析。研究表明:摩擦系数对接触斑面积、接触区Mises应力值和法向接触应力影响不大;随着摩擦系数的增大,接触斑黏着区面积增加,接触区内横向和垂向剪应力增大且位置向接触区表面靠近;在相同牵引力矩作用下,随着摩擦系数的增加,轮轨纵向剪应力明显增大;接触斑内摩擦力矢量的纵向分量也随之增大,轮轨摩擦力及其绕原点合力矩的纵向分量也变化明显,最大增幅超过30%,自旋力矩值也随之增大且其中心点在接触斑内沿牵引方向前移。