Simulation of Train-Track Interaction with Stochastic Track Properties

A numerical method to simulate vertical dynamic interaction between a moving train and a railway track was extended to account for stochastic properties in the track structure. The numerical simulations are carried out in the time-domain with a moving mass model. Full-scale measurements in the field and laboratory experiments were carried out to obtain data for the stochastic track model. The values of the stochastic variables are thus chosen to correspond to real tracks. To investigate the influence of the randomness of selected stochastic parameters in the track structure, the Latin Hypercube sampling method with correlation control was used to generate stochastic realisations.     

Simulation of Train-Track Interaction with Stochastic Track Properties

A numerical method to simulate vertical dynamic interaction between a moving train and a railway track was extended to account for stochastic properties in the track structure. The numerical simulations are carried out in the time-domain with a moving mass model. Full-scale measurements in the field and laboratory experiments were carried out to obtain data for the stochastic track model. The values of the stochastic variables are thus chosen to correspond to real tracks. To investigate the influence of the randomness of selected stochastic parameters in the track structure, the Latin Hypercube sampling method with correlation control was used to generate stochastic realisations.     

Flange Force Effects on the Motion of a Train Wheelset

The motion of a train wheelset is investigated using Hopf bifurcation theory. The method takes full account of the nonlinear effects of the flange-rail contact forces which are incorporated in the model; The numerical solution is obtained over a wide range of forward speeds by transforming the bifurcation problem into a regular nonlinear boundary value problem, which is solved by standard methods. This solution is shown to be orbitally, asymptotically stable. The algorithm supplies complete information on the lateral and yaw motions and on the period of oscillation, even for very high forward speeds.     

Dynamic Interaction of Railway Train and Bridges

An analytical method for obtaining the dymanic responses of a train of locomotives moving on bridges is presented. The ratio of dynamic response to maximum static response is called the amplification factor, and its maximum absolute value minus one is called the impact. Each four-axle locomotive is modelled as a rigid body with three degrees of freedom: bounce, pitch and roll, and with a suspension system consisting of springs mounted on wheels. The locomotives are assumed to be connected by frictionless joints to form the train. The bridge is modelled as a three dimensional structure, with the masses lumped at the truss joints. All joints, including the floor beam connections, are assumed to be rigid, except those for the bracing members, which are assumed to be hinged. Vertical displacements are considered as the only dynamic degree of freedom. The mathematical formulation is described briefly, and a numerical example is given. Locomotive and truss member properties, together with stresses in some typical members, are given in the tables. The amplification factors of the responses in some typical bridge members are shown in the figures.     

Dynamic Interaction of Railway Train and Bridges

SUMMARY

An analytical method for obtaining the dymanic responses of a train of locomotives moving on bridges is presented. The ratio of dynamic response to maximum static response is called the amplification factor, and its maximum absolute value minus one is called the impact. Each four-axle locomotive is modelled as a rigid body with three degrees of freedom: bounce, pitch and roll, and with a suspension system consisting of springs mounted on wheels. The locomotives are assumed to be connected by frictionless joints to form the train. The bridge is modelled as a three dimensional structure, with the masses lumped at the truss joints. All joints, including the floor beam connections, are assumed to be rigid, except those for the bracing members, which are assumed to be hinged. Vertical displacements are considered as the only dynamic degree of freedom. The mathematical formulation is described briefly, and a numerical example is given. Locomotive and truss member properties, together with stresses in some typical members, are given in the tables. The amplification factors of the responses in some typical bridge members are shown in the figures.     

Modelling of Railway Track and Vehicle/Track Interaction at High Frequencies

Abstract

A review is presented of dynamic modelling of railway track and of the interaction of vehicle and track at frequencies which are sufficiently high for the track's dynamic behaviour to be significant. Since noise is one of the most important consequences of wheel/rail interaction at high frequencies, the maximum frequency of interest is about 5kHz: the limit of human hearing. The topic is reviewed both historically and in particular with reference to the application of modelling to the solution of practical problems. Good models of the rail, the sleeper and the wheelset are now available for the whole frequency range of interest. However, it is at present impossible to predict either the dynamic behaviour of the railpad and ballast or their long term behaviour. This is regarded as the most promising area for future research.     

Modelling of Railway Track and Vehicle/Track Interaction at High Frequencies

A review is presented of dynamic modelling of railway track and of the interaction of vehicle and track at frequencies which are sufficiently high for the track's dynamic behaviour to be significant. Since noise is one of the most important consequences of wheel/rail interaction at high frequencies, the maximum frequency of interest is about 5kHz: the limit of human hearing. The topic is reviewed both historically and in particular with reference to the application of modelling to the solution of practical problems. Good models of the rail, the sleeper and the wheelset are now available for the whole frequency range of interest. However, it is at present impossible to predict either the dynamic behaviour of the railpad and ballast or their long term behaviour. This is regarded as the most promising area for future research.     

Dynamic Simulation of Taipei EMU Train

Simplified train dynamics for the trains of the Taipei Metro are presently being studied, with the aid of numerical methods, to avoid possible dangerous conditions of coupler failure and to understand the deformation of the “mechanical fuse” in a train collision. A multiple degree-of-freedom system is utilized to simulate the EMU train. Equations of motion are set up in a matrix and solved to calculate the transient responses of the couplers. Analytical solutions are checked by comparison with the results of the Runge-Kutta method. Energy absorption devices such as the coupler and the “mechanical fuse” as well as the vehicle body structure are taken into consideration to complete an integrated study of the structural crashworthiness. It is found that sudden failure of couplers would not happen for a train at coupling speeds up to 5 km/h. Coupler force for a train running at a normal acceleration from the start or at an emergency stop are also investigated. In addition, it is found that damage is confined to the fuse structures and the fuse deformation is less than the maximum allowable deformation designed in the trains, under an impact speed of 25 km/h.     

高速公路弯道行车轨迹仿真与影响因素分析

针对山区高速公路弯道事故高发的特点,对山区高速公路的弯道行车轨迹进行了仿真研究。首先考虑山区高速公路汽车行驶状态的非线性特性,建立基于非线性的5自由度汽车动力学模型的驾驶员-汽车-道路闭环操纵系统模型,然后应用模型对山区高速公路弯道的行车轨迹进行了模拟仿真,通过对不同道路条件下行车轨迹的对比分析,得到其对高速公路曲线段行车轨迹的影响规律：随着圆曲线曲率的增加,缓和曲线长度的减少,曲线超高的增大,行车轨迹侧向偏移越大。仿真结果对高速公路曲线段道路交通安全管理提供了理论支持。     

摩托车配气机构运动学和动力学模拟分析

根据配气机构运动学和动力学分析,试制了优化凸轮实物,采用优化凸轮进行了发动机对比性能试验和耐久性试验.试验表明,优化凸轮能满足发动机性能要求,发动机耐久试验后,优化凸轮没有出现异常磨损现象,和模拟分析结果一致.     

CATIA运动仿真在汽车设计中的应用

介绍了汽车总体设计要求,阐述了电子虚拟装配及运动仿真模型建立基本过程,根据电子虚拟装配及运动仿真特点,讨论其在汽车总体设计中的应用。     

地铁列车荷载作用位置对道床与管片剥离的影响研究

城市地铁盾构区间隧道若出现道床与管片剥离病害,会直接威胁到列车的运行安全。以某地铁区间线路为背景,通过数值模拟研究了列车运行过程中对道床和管片剥离影响最大的荷载位置。根据荷载作用在道床上的不同位置,发现荷载在远离道床伸缩缝的过程中相邻道床底部的拉应力值急剧减小,确定了荷载最不利位置为道床靠近伸缩缝处,可为模型试验和病害治理提供参考。     

城市轨道交通列车开行方案运行仿真研究

分析了列车开行方案的特点和要素,运用多质点模型设计了多列车追踪运行计算模型,讨论了多方案运行仿真中遇到的多种问题及其解决方案,如单交路情况、多交路情况、交路间的协调控制、不同方案间的平滑过渡等.在此基础上,设计了仿真系统的总体流程,并通过算例验证了系统的有效性.     

发动机总成悬置系统的仿真优化设计

对于某轿车在怠速时发动机总成振动较大的情况,建立发动机悬置系统参数化模型,利用能量法基本原理,通过机械系统动力学仿真软件ADAMS对该发动机悬置系统进行仿真分析,得到系统的固有特性,并对悬置优化设计,减小悬置支反力的幅值,从而提高发动机的隔振效率,降低整车的振动,解决怠速时的隔振问题。     

新型四冲程发动机液压可变配气机构的动态仿真与分析

提出一种新型的四冲程发动机液压可变配气机构。建立系统非线性数学模型,并分析配气机构的动态特性。仿真和试验结果表明,新的液压配气机构能实现可变气门正时及开度的控制,可适用于高转速发动机,具有一定的实用性。     

Dynamic Train-Track Interaction: Variability Attributable to Scatter in the Track Properties

A numerical method to simulate vertical dynamic interaction between a rolling train and a railway track has been used to investigate the influence of stochastic properties of the track structure. A perturbation technique has been used to investigate the influence of the scatter in selected track properties. The train-track interaction problem has been numerically solved by use of an extended state-space vector approach in conjunction with a complex modal superposition for the whole track structure. All numerical simulations have been carried out in the time-domain with a moving mass model. Properties such as rail pad stiffness, ballast stiffness, dynamic ballast-subgrade mass and sleeper spacing have been studied. To obtain sufficient statistical information from track structures, full-scale measurements in the field and laboratory measurements have been carried out. The influence of scatter in the track properties on the maximum contact force between the rail and the wheel, the maximum magnitude of the vertical wheelset acceleration, and the maximum sleeper displacement have been studied. Mean values and standard deviations of these quantities have been calculated. The effects of the variation of the investigated track properties are discussed.