车轮与高速道岔翼轨的接触分析

为合理设计道岔,更好地匹配轮对和道岔型面,用有限元法求解车轮与高速道岔翼轨的接触问题.建立4种不同型面车轮与高速道岔翼轨接触的有限元模型,分析车轮通过高速道岔翼轨的轮岔接触斑和等效应力的变化规律,计算结果表明:机车车轮与翼轨的接触斑位于翼轨轨顸外侧,动车车轮与翼轨接触的接触斑位置在翼轨轨顶中部;磨耗后JM3型面车轮与翼轨接触时,容易出现应力集中,尤其是在距离心轨尖端50 cm位置处;磨耗后JM3型面车轮与翼轨接触产生的等效应力最大.     

基于多体动力学的车辆道岔通过性能研究

道岔复杂的轮轨关系及其变截面特性是车辆通过道岔时引起振动甚至脱轨的关键因素.根据60kg/m钢轨18号可动心轨道岔设计布置图,在多体动力学软件中建立车辆—道岔耦合系统模型,在此基础上对车辆—道岔系统模型进行验证,仿真计算车辆侧向和直向通过道岔的动力学响应.结果表明转辙器区、辙叉区轨道截面变化和轮轨型面匹配是影响车辆动力学性能的主要因素.最后,对车辆侧向通过离散轨道模型工况下的动力学响应进行仿真计算,讨论道岔轨下整体刚度和阻尼对模型动力学性能的影响,为改善车辆通过道岔时的动力学性能、道岔轨下刚度与阻尼参数匹配提供理论基础.     

Wheel/rail contact geometry on tight radius curved track: simulation and experimental validation

In this investigation, a numerical procedure for wheel/rail one and two-point contact geometry analysis is developed for predicting the location of contact points in curved negotiations on a tight radius curved track. The proposed method accounts for the change in the longitudinal location of contact point along the curved track as well as the circumferential contact point on the wheel flange. For the purpose of validation, simulation results for one and two-point contact scenarios are compared with those obtained using the experiment. The experiment is performed on a test track of R48 curve using an actual truck, and the location of contact points for given lateral and yaw displacements are measured on the tight radius curved track. It is demonstrated that good agreements are obtained between the simulation and experimental results in tread and flange contacts.     

起重机轮轨接触分析的参数化建模方法及其应用

为准确快速地对起重机钢制车轮踏面与轨道接触应力的分布状况进行有限元分析,运用ANSYS APDL参数化建模,建立常见的起重机车轮与轨道接触分析的数值模型。该模型通过输入必要的车轮几何参数、网格划分参数和载荷参数即可自行完成实体建模、网格划分、载荷施加和求解。实例应用结果证明整合几何参数化和网格划分参数化的建模方法可大大提高起重机轮轨接触分析效率。     

Railway multibody simulation with the knife-edge-equivalent wheel–rail constraint equations

This paper describes a new numerical procedure for the modelling and simulation of the wheel–rail contact in railway dynamic simulations. The method is called knife-edge-equivalent contact constraint method, or simply KEC-method. Using this method, the wheel–rail contact is modelled as rigid or constraint-based using a set of kinematic constraints that eliminates one-degree of freedom of relative wheel–rail motion. The KEC-method uses a transformed but equivalent wheel profile in contact with a single-point rail. This equivalent profile has the property of producing the same wheelset-rail relative kinematics as the real wheel–rail profiles. The method can be used efficiently online while achieving better computational times than using contact lookup tables. Compared with existing constraint methods, the KEC-method has the following advantages: (1) simplification of the wheel–rail contact constraints, (2) simplified wheel–rail profiles, (3) online solution of the contact constraints, (4) reduction of the number of surface parameters, and (5) increased computational efficiency. A comparative study with respect to the use of efficient contact lookup tables in the simulation of Metro de Sevilla (metropolitan train in the city of Sevilla) shows that this contact method is appropriate to simulate the dynamics of a railway vehicle efficiently.

     

Effect of tangent track buckle on vehicle derailment

In order to investigate the effect of a tangent track buckle on the dynamic derailment of a railway vehicle, a coupled vehicle/track dynamics model is developed, in which the vehicle is modeled as a 35 D.O.F. multibody system and the track is modeled as a 3-layer discrete elastic support model. Rails are assumed to be Timoshenko beams supported by discrete sleepers, and the effects of vertical and lateral motions and rolling of the rail on the wheel/rail creepages are taken into account. The sleepers are treated as Euler beams on elastic foundation for the vertical vibration, while as lumped masses in the lateral direction. A moving sleeper support model is developed to simulate the effect of the periodical discrete sleepers on the vehicle/track interaction. The vehicle and the track are coupled by wheel/rail contacts whereas the normal forces and the creep forces are calculated using the Hertzian contact theory and the nonlinear creep theory by Shen et al., respectively. The equations of motion of the coupled vehicle/track system are solved by means of an explicit integration method. A tangent track buckle is simulated with a cosine function, which describes the misalignment of the track with different lengths due to its buckling. In the analysis the effects of the buckle wavelength and amplitude and of the vehicle speed on the dynamic behavior of the coupled vehicle/track system are considered. The present paper analyzes in detail the conventional derailment coefficients which include the ratio of the wheel/rail lateral force to the vertical force, the wheel load reduction, and the new criteria indicating the wheel/rail contact point traces and the wheel rise with respect to the rail. These criteria are simultaneously used to evaluate the risk of derailment of the whole vehicle. The numerical results obtained indicate that the track misalignment caused by the buckle and the vehicle speed have a great influence on the whole vehicle running safety when the vehicle passes through the buckled tangent track.     

Wheel-rail contact elements incorporating irregularities

The aim of this study is to simulate the dynamic vertical response of a vehicle traversing rigid rails and a railway bridge. This is achieved by using the authors' wheel-rail contact element (WRC) to model the dynamic interaction that exists between a sprung wheel, using a Hertzian spring, and the rail. The objective in creating these elements was to model the rail and wheel irregularities, which was not a feature of the contact elements within the ANSYS finite element program. In this paper the numerical results generated using the authors' WRC element are identical to the results generated using the commercial contact element of ANSYS for a smooth rail condition. In the case of irregular rails, the numerical results generated using the authors' WRC elements compare very favourably with the results from the literature.     

Determination of wheel–rail contact points with semianalytic methods

The multibody simulation of railway vehicle dynamics needs a reliable and efficient method to determine the location of the contact points between wheel and rail that represent the application points of the contact forces and influence their directions and intensities. In this work, two semi-analytic procedures for the detection of the wheel–rail contact points (named the DIST and the DIFF methods) are presented. Both the methods consider the wheel and the rail as two surfaces whose analytic expressions are known. The first method is based on the idea that the contact points are located in the point in which the distance between the contact surfaces has local maxima, and is equivalent to solve an algebraic 4D-system. The second method is based on the idea that in the contact points the difference between the surfaces has local minima and is equivalent to solve an algebraic 2D-system. In both cases, the original problem can be reduced analytically to a simple 1D-problem that can be easily solved numerically.     

柔性轮对结构振动对车辆动力学性能的影响

为研究轮对柔性对车辆动力学的影响,建立高速列车轮对的有限元模型,对轮对进行自由模态分析.通过模态综合法获取柔性轮对模态信息,应用多体系统动力学理论建立柔性轮对-刚性轨道接触力学模型;建立包含高速旋转柔性轮对的车辆-轨道耦合动力学模型,研究高速列车在直线和曲线通过时轮对结构振动对车辆动力学性能的影响.结果表明:轮对的结构振动对轮轨接触点位置、蠕滑率、蠕滑力和脱轨因数等均产生较明显的影响,但是对轮重减载率影响较小,因此应采用更加精确的柔性轮轨耦合模型研究轮轨相互作用、轮轨滚动接触疲劳和轮轨噪声等.     

基于多体系统动力学和有限元法的联合仿真在车桥耦合振动研究中的应用*

为了实现车桥耦合振动精细化仿真研究,利用多体系统动力学软件SIMPACK建立完整的车辆空间模型,采用空间杆系和板壳混合单元有限元方法建立桥梁的动力分析模型;然后将车辆和桥梁两个子系统在轮轨接触面离散的信息点上进行数据交换,实现车桥耦合振动联合仿真分析。以高速铁路上的简支梁桥为研究对象,采用基于多体系统动力学和有限元法结合的联合仿真技术,计算了弹性轮轨接触时动车组列车以不同车速通过桥梁的空间耦合振动响应,证明了该研究方法的可行性。     

钢轨波磨对地铁车辆动力学响应的影响

建立地铁车辆-轨道耦合动力学模型,将钢轨视为弹性离散点支撑的无限长Timoshenko梁,将实测钢轨短波波磨不平顺数据作为不平顺激励.通过数值计算得到在科隆蛋扣件线路上不平顺发展过程中车辆动力学响应的变化情况.随着短波波磨不平顺幅值的增大,轮对和转向架的横、垂向加速度以及轮轨横、垂向力均呈增大趋势,且受不平顺程度的影响较大.结果表明钢轨波磨主要影响车辆系统的垂向振动.     

A new method for modelling and simulation of the dynamic behaviour of the wheel-rail contact

This paper presents a new method for modelling and simulation of the dynamic behaviour of the wheel-rail contact. The proposed dynamic wheel-rail contact model comprises wheel-rail contact geometry, normal contact problem, tangential contact problem and wheelset dynamic behaviour on the track. This two-degree of freedom model takes into account the lateral displacement of the wheelset and the yaw angle. Single wheel tread rail contact is considered for all simulations and Kalker s linear theory and heuristic non-linear creep models are employed. The second order differential equations are reduced to first order and the forward velocity of the wheelset is increased until the wheelset critical velocity is reached. This approach does not require solving mathematical equations in order to estimate the critical velocity of the dynamic wheel-rail contact model. The mathematical model is implemented in Matlab using numerical differentiation method. The simulated results compare well with the estimated results based on classical theory related to the dynamic behaviour of rail-wheel contact so the model is validated.     

滚动接触疲劳载荷对铁轨表面接触疲劳裂纹应力强度系数的影响

为研究轮轨滚动接触疲劳(Rolling Contact Fatigue,RCF)载荷对铁轨表面裂纹应力强度系数的影响,以UIC60铁轨轮廓尺寸为依据建立轮轨接触的三维有限元模型,通过改变RCF载荷大小、轮轨表面摩擦因数和接触中心位置等轮轨接触的输入参数,计算铁轨表面接触裂纹尖端的应力强度系数,分析RCF载荷对铁轨表面接触疲劳裂纹的影响.结果表明RCF载荷作为控制铁轨表面接触裂纹的重要因素,其变化直接导致裂纹尖端应力强度系数的变化,从而改变裂纹的扩展状况.为减缓铁轨表面裂纹的扩展,可以针对载荷采取均匀分布载重量、使用润滑剂降低轮轨摩擦因数等相应措施.     

滚动接触疲劳载荷对铁轨表面接触疲劳裂纹应力强度因子的影响

为研究轮轨滚动接触疲劳（Rolling Contact Fatigue,RCF）载荷对铁轨表面裂纹应力强度因子的影响,以UIC60铁轨轮廓尺寸为依据建立轮轨接触的三维有限元模型,通过改变RCF载荷大小、轮轨表面摩擦因数和接触中心位置等轮轨接触的输入参数,计算铁轨表面接触裂纹尖端的应力强度因子,分析RCF载荷对铁轨表面接触疲劳裂纹的影响. 结果表明RCF载荷作为控制铁轨表面接触裂纹的重要因素,其变化直接导致裂纹尖端应力强度因子的变化,从而改变裂纹的扩展状况;为减缓铁轨表面裂纹的扩展,可以针对载荷采取均匀分布载重量、使用润滑剂降低轮轨摩擦因数等相应措施.     

高速铁道车辆悬挂系统参数化建模、优化与仿真分析

为了协调高速铁道车辆的运动稳定性与曲线通过性能之间的矛盾,本文采用多目标优化方法对一种高速铁道车辆的关键悬挂参数进行了优化处理.采用多体动力学技术建立了某型高速铁道车辆62个自由度的动力学模型,模型考虑了轮轨接触几何非线性、轮轨蠕滑非线性和阻尼非线性等.采用ADAMS-Matlab联合仿真对车辆悬挂系统进行参数化改造,使弹簧刚度和阻尼系数均可调.采用基于遗传算法的多目标优化方法对悬挂参数进行优化,使车辆模型能同时满足3种动力学指标.对比优化前后模型的动力学性能可以发现:模型的运动稳定性和曲线通过性能得到显著提高,虽然运行平稳性有小幅降低,但仍能保持在优良的工作状态.     

长春轻轨3号线钢轨轨底坡对列车车轮磨耗的影响

摘要： 为探究小半径曲线钢轨轨底坡对车轮磨耗的影响规律,建立长春市轻轨3号线70%低地板轻轨列车车轮磨耗预测分析模型,包括独立旋转轮对的车辆 轨道耦合动力学计算模型、轮轨接触模型和Archard材料磨耗模型,并采用这些模型分析轻轨列车通过小半径曲线轨道时轨底坡对车轮磨耗的影响。分析结果表明：轻轨列车通过小半径曲线轨道时,动车轮对的磨耗程度比拖车轮对更严重,动车轮对总磨耗量为拖车轮对总磨耗量的159%;从轮对自身来看,内侧车轮的磨耗均比外侧车轮的磨耗严重,内侧车轮总磨耗量为外侧车轮总磨耗量的165%;钢轨轨底坡对车轮磨耗的影响显著,车轮踏面最大磨耗量出现位置随轨底坡变化的规律较为复杂,车轮轮缘磨耗量在轨底坡为1/20时最小。     

变轨距货车转向架的动力学分析

建立了考虑轮轴间隙的三大件式变轨距货车转向架动力学模型,研究车辆在准轨和宽轨线路上的动力学性能和LM踏面在不同轨距线路上的轮轨接触关系.考虑轨距为1435mm和1520mm、轨底坡为1/40和1/20、标准和打磨后的多种钢轨廓形与LM踏面匹配,发现LM踏面对两种轨底坡的兼容性较好,而踏面磨耗后对轨底坡变化较敏感;LM踏面在准轨线路上对轮轴横向间隙比较敏感,而在宽轨线路上则不存在这个问题.轮轴之间的横向和旋转间隙会导致车辆临界速度降低,建议控制间隙在0.6mm和0.5mrad以内;轮轴间隙不影响车辆运行安全性和平稳性,且在准轨和宽轨线路上的动力学指标基本无差异.变轨距车辆运行过程中,轮轨横向力和纵向蠕滑力会导致轮轴横向间隙和旋转间隙动态变化,变化量为间隙值;给出轮轴间隙与轮轨载荷的正态分布统计,发现轮轴间隙载荷与轮轨载荷相当.     

An inverse shape design method for railway wheel profiles

Optimisation of a railway vehicle–track system is a complex process. The paper presents a procedure for optimal design of a wheel profile based on geometrical wheel/rail contact characteristics such as the rolling radii difference (RRD). The procedure uses optimality criteria based on an RRD function. The criteria account for stability of wheelset, cost efficiency, minimum wear of wheels and rails as well as safety requirements. The shape of the wheel profile approximated by a piecewise cubic Hermite interpolating polynomial is varied during the optimisation process to satisfy the optimality criteria. A numerical technique called multipoint approximations based on response surface fitting (MARS) has been chosen as an optimisation method. The proposed optimum design procedure has been applied to improve the performance of metro trains in Rotterdam (RET), The Netherlands. The trains were suffering from severe wheel tread wear and as a result of that from lateral vibrations (hunting). Using the proposed procedure, a new wheel profile has been obtained and applied to the RET metro trains. The results of the optimisation have shown that the performance of a railway vehicle can be improved by improving the contact properties of the wheel and rail. After the application of the optimised wheel profile, the instability of the metro trains has been eliminated and the lifetime of the wheels has been increased from 15,000 to 120,000 km.     

Kalman filter for adaptive learning of two-dimensional look-up tables applied to OCV-curves for aged battery cells

In online automotive applications it is common to use look-up tables, or maps, to describe nonlinearities in component models that are to be valid over large operating ranges. If the component characteristics change with aging or wear, these look-up tables must be updated online. For 2-D look-up tables, the existing methods in the literature only adapt the observable parameters in the look-up table, which means that parameters in operation points that have not been visited for a long time may be far from their true values. In this work, correlations between different operating points are used to also update non-observable parameters of the look-up table. The method is applied to Open Circuit Voltage (OCV) curves for aged battery cells. From laboratory experimental data it is demonstrated that the proposed method can significantly reduce the average deviation from an aged OCV-curve compared to keeping the OCV-curve from the beginning of the cell’s life, both for observable and non-observable parameters.