• Title, Summary, Keyword: Vehicle-Track Interaction

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Development of a Numerical Analysis Method of Train/Track Interaction for Evaluation of Dynamic Track Design Load (궤도 설계 동하중 산정을 위한 차량/궤도 상호작용 해석기법 개발)

  • 양신추
    • Proceedings of the KSR Conference
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    • pp.1094-1099
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    • 2002
  • In this paper, a numerical method for vehicle-track interaction analysis is developed to evaluate vertical dynamic force subjected to rail surface. A vehicle is modelled by lumped masses system and track by multi layered continuous beam system. The equation of motion of vehicle and track interaction system is derived by considering compatibility condition at the contact points between wheel and rail. The input vibration source is given by the empirical formula of power spectral density of track irregularity, which is suggested by FRA. Using this method, dynamic impact factors with the train speed are evaluated.

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The Effect of Gaps in Concrete Bearing Surface of Direct Fixation Track on Vehicle and Track Interaction (직결궤도 체결구 하부에 발생한 단차가 차량/궤도 상호작용에 미치는 영향)

  • Yang, Sin-Chu;Kim, Eun
    • Proceedings of the KSR Conference
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    • pp.50-57
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    • 2010
  • Various installation faults may lie in fasteners in the construction of a direct-fixation track by the top-down method. At an extreme, they may cause excessive interaction between the train and track, compromise the running safety of the train, and cause damage to the track components. Therefore, the faults need to be kept within the allowable level through an investigation of their effects on the interactions between the train and track. In this study, the vertical dynamic stiffness of fasteners in installation faults was measured based on the dynamic stiffness test by means of an experimental apparatus that was devised to feasibly reproduce gap faults. This study proposes an effective analytical model for a train-track interaction system in which most elements, except the nonlinear wheel-rail contact and some components that behave bi-linearly, exhibit linear behavior. To investigate the effect of the behavior of fasteners in gap faults in a direct-fixation track on the vehicle and track, vehicle-track interaction analyses were carried out, targeting key review parameters such as the wheel load reduction factor, vertical rail displacement, rail bending stress, and mean stress of the elastomer. From the results, it was noted that the gap faults in the concrete bearing surface of a direct-fixation track need to be limited for the sake of the long-term durability of the elastomer than for the running safety of the train or the structural safety of the track.

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Additional Axial Stress of CWR Track on the Bridge according to the Variation of Design Vehicle Load (설계차량하중 변화에 따른 교량상 장대레일 궤도의 부가축응력)

  • Yun, Kyung-Min;Jeon, Byeong-Heun;Choi, Shin-Hyung;Lim, Nam-Hyou
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.1
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    • pp.807-813
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    • 2015
  • The CWR(Continuous Welded Rail) on a bridge shows complex structural behavior compared to those on the roadbed. The influence factors on the track-bridge interaction are the variation of temperature and vehicle load. The analysis methods for track-bridge interaction, material property, modeling method, loads and combination method are indicated in the domestic railway design principle, KR C-08080. The vehicle load in KR C-08080 was changed in 2014. In this study, to evaluate the effect of the changed vehicle load on the track-bridge interaction, the track-bridge interaction analyses were performed for 22 bridges by using finite element method.

Vehicle/track dynamic interaction considering developed railway substructure models

  • Mosayebi, Seyed-Ali;Zakeri, Jabbar-Ali;Esmaeili, Morteza
    • Structural Engineering and Mechanics
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    • v.61 no.6
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    • pp.775-784
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    • 2017
  • This study is devoted to developing many new substructure models for ballasted railway track by using the pyramid model philosophy. As the effect of railway embankment has been less considered in the previous studies in the field of vehicle/track interaction, so the present study develops the pyramid models in the presence of railway embankment and implements them in vehicle/track interaction dynamic analyses. Considering a moving car body as multi bodies with 10 degrees of freedom and the ballasted track including rail, sleeper, ballast, subgrade and embankment, two categories of numerical analyses are performed by considering the new substructure systems including type A (initiation of stress overlap areas in adjacent sleepers from the ballast layer) or type B (initiation of stress overlap areas in adjacent sleepers from the subgrade layer). A comprehensive sensitivity analyses are performed on effective parameters such as ballast height, sleepers spacing and sleeper width. The results indicate that the stiffness of subgrade, embankment and foundation increased by increasing the ballast height. Also, by increasing the ballast height, rail and ballast vertical displacement decreased.

Study of the Interaction between a Tracked Vehicle and the terrain (궤도차량과 토양의 상호관계에 대한 연구)

  • 박천서;이승종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.144-147
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    • 2001
  • The planar tracked vehicle model used in this investigation consists of two kinematically decoupled subsystem, i.e., the chassis subsystem and the track subsystem. The chassis subsystem include the chassis frame, sprocket, idler and rollers, while the track subsystem is represented as a closed kinematic chain consisting of rigid links interconnected by revolute joints, In this paper, the recursive kinematic and dynamic formulation of the tracked vehicle is used to find the vertical forces and the distances of the certain track moved in the driving direction along the track. These distances and vertical forces obtained are used to calculate the sinkage of a terrain. The FEM is adopted to analyze the interaction between the tracked vehicle and terrain. The terrain is represented by a system of elements with specified constitutive relationships and considered as a piecewise linear elastic, plastic and isotropic material. When the tracked vehicle is moving with different speeds on the terrain, the elastic and plastic deformations and the maximum sinkage for the four different types of a isotropic soil are simulated.

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A study on the Settlement of Ballasted Track according to Various Rail-Pad Stiffness (레일패드의 강성이 자갈궤도 침하에 미치는 영향 연구)

  • Choi, Jin-Yu;Kim, Eun;Hwang, Man-Ho;Choi, Su-Ik
    • Proceedings of the KSR Conference
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    • pp.249-255
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    • 2010
  • Ballasted track is under the circumstance of repetition of deterioration and recovery. Track deterioration is presented as track irregularity or settlement, and dynamic force subjected to track is one of major cause of the deterioration. The dynamic force is determined from the dynamic interaction between track and vehicle. Rail-pad stiffness is one of the factor affects track dynamic property. In this study, the relationship between rail-pad stiffness and track settlement was investigated. Dynamic forces according to various rail-pad stiffness was obtained from the dynamic vehicle-track interaction analysis using DARTS-NL. Track settlement was calculated by substitution the dynamic forces into various formulas for track settlement. From the result of analysis, it was known that the track settlement is increased about 6% when the rail-pad stiffness rise about twice. And this result leads that there is only a little relationship between rail-pad stiffness and track settlement.

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Dynamics of high-speed train in crosswinds based on an air-train-track interaction model

  • Zhai, Wanming;Yang, Jizhong;Li, Zhen;Han, Haiyan
    • Wind and Structures
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    • v.20 no.2
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    • pp.143-168
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    • 2015
  • A numerical model for analyzing air-train-track interaction is proposed to investigate the dynamic behavior of a high-speed train running on a track in crosswinds. The model is composed of a train-track interaction model and a train-air interaction model. The train-track interaction model is built on the basis of the vehicle-track coupled dynamics theory. The train-air interaction model is developed based on the train aerodynamics, in which the Arbitrary Lagrangian-Eulerian (ALE) method is employed to deal with the dynamic boundary between the train and the air. Based on the air-train-track model, characteristics of flow structure around a high-speed train are described and the dynamic behavior of the high-speed train running on track in crosswinds is investigated. Results show that the dynamic indices of the head car are larger than those of other cars in crosswinds. From the viewpoint of dynamic safety evaluation, the running safety of the train in crosswinds is basically controlled by the head car. Compared with the generally used assessment indices of running safety such as the derailment coefficient and the wheel-load reduction ratio, the overturning coefficient will overestimate the running safety of a train on a track under crosswind condition. It is suggested to use the wheel-load reduction ratio and the lateral wheel-rail force as the dominant safety assessment indices when high-speed trains run in crosswinds.

Study of the Interaction between Tracked Vehicle and Terrain (궤도차량과 토양의 상호작용에 대한 연구)

  • Park, Cheon-Seo;Lee, Seung-Jong
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.2
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    • pp.140-150
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    • 2002
  • The planar tracked vehicle model used in this investigation consists of two kinematically decoupled subsystems, i.e., the chassis subsystem and the track subsystem. The chassis subsystem includes the chassis frame, sprocket, idler and rollers, while the track subsystem is represented as a closed kinematic chain consisting of rigid links interconnected by revolute joints. In this study, the recursive kinematic and dynamic formulation of the tracked vehicle is used to find the vertical terce and the distance of an arbitrary track moved in the driving direction along the track. These distances and vertical forces obtained are used to get the deformation and sinkage of a terrain. The FEM(Finite Element Method) is adopted to analyze the interaction between tracked vehicle and terrain. The terrain is represented by a system of elements wish specified constitutive relationships and considered as a piecewise linear elastic, plastic and isotropic material. When the tracked vehicle is moving with different speeds on the terrain, the elastic and plastic deformations and the maximum sinkage for the four different types of isotropic soils are simulated.

Optimal Design of Reinforced Rail over Connection Section of Bridge and Embankment (교량/토공 접속구간 보강레일의 최적설계)

  • Yang, S.C.;Kang, Y.S.;Kim, E.
    • Proceedings of the KSR Conference
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    • pp.256-263
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    • 2002
  • This paper deal with optimal design of reinforced track as a track reinforcing method for transition area of track support stiffness in transition area between bridge and earthwork. When vehicle passes through transition area, dynamic properties between vehicle and track are studied by the analysis of vehicle-train interaction for the each case when reinforced tracks are used or not. furthermore, optimum decision of type and length of track are made based on the performance adapting variable parameters : support stiffness of track for bridge and earthwork, heading direction of vehicle and type and length of track.

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Evaluation on Allowable Vehicle Speed Based on Safety of Track and Railway Bridge (궤도 및 교량 안전성을 고려한 열차 증속가능 속도대역 평가)

  • Bahng, Eun Young
    • Journal of the Korean Society of Safety
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    • v.33 no.2
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    • pp.145-151
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    • 2018
  • In this study, the track-bridge interaction analysis was performed using an analytical model considering the track structure, thereby taking into account the linear conditions (R=650 m, cant variation $160{\pm}60mm$) and the dynamic characteristics of the bridge. As a result of the study, the allowable speed on the example bridge considered was calculated at 200 km/h based on vertical deflection, vertical acceleration, and irregularity in longitudinal level, but was also evaluated at 170km/h based on the coefficient of derailment, wheel load reduction, and lateral displacement of the rail head. It is considered desirable to set the speed 170km/h to the speed limit in order to secure the safety of both the bridge and the track. It is judged that there will be no problems with ensuring rail protection and train stability in the speed band.