• Title, Summary, Keyword: Rail stress

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The Fatigue Life Evaluation of Rail on the Concrete Track of High Speed Railway by Analysis of the Vehicle/Track Interaction (차량/궤도 상호작용해석을 통한 고속철도 콘크리트궤도 레일의 피로수명 예측)

  • Lim, Hyoung-Jun;Sung, Deok-Yong;Park, Yong-Gul
    • Journal of The Korean Society of Civil Engineers
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    • v.32 no.6D
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    • pp.663-671
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    • 2012
  • The demand of CWR is rapidly increasing because of the adaptation of concrete track, the need for rapid and comfortable ride, and the reduction of maintenance cost. Because of short applying period of the concrete track, there is not a case of CWR fracture in Korea caused by repeated load of the train, which makes it difficult to calculate replacement period of rail based on rail fatigue life using an actual field data. This study thus inspected the bending stress at rail bottom through analyzing the vehicle/track interaction, performed multiple regression analysis on the data, deducted the bending stress prediction equations by the speed and the surface irregularity. Finally, the fatigue life of CWR on the concrete track was predicted based on the prediction equations for bending stress at rail bottom.

Quality Assurance of Rail grinding and Optimize grinding Strategy (레일 연마의 품질보증과 최적 연마 전략)

  • Lee Hak-Kyu;Lee Jong-Su;Lee Ki-Seung;Cho Sun-Kyu
    • Proceedings of the KSR Conference
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    • pp.283-289
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    • 2004
  • Rail defects(Corrugation, shelling, etc) are occurred by the Rail with wheel contact stress. Rail grinding is maintaining of optimal rail profile to use special rail grinding machine to remove rail defect. The benefits of rail grinding enforcement, improve track safety, improve track steering and rail life, improve ride comfort and reduce noise, etc. Actually when rail grinding plan apply to field track, we should consider a lot of function before determination, such as grinding method, grinding pass number, removing metal volume, etc. because each track has various characteristics. Therefore it is important that the determination of rail grinding strategy for optimum and economic before enforcement.

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Rail Pressure on the Changing Point of Track Modulus (궤도강성변화구간의 레일압력 분포에 관한 연구)

  • 이기승;천진녕;김성칠;권순섭
    • Proceedings of the KSR Conference
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    • pp.228-233
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    • 2002
  • The transition between bridge or tunnel and plain track has different rail pressure and distributed stress on formation. This paper shows distribution of rail pressure on transition at which spring stiffness are changed. By this study, it is revealed that the changing into relatively high stiffness causes increased rail pressure visibly and draw up dynamic track force. A medium stiffness structure and reinforced rail could be effective for reducing track force on the transition.

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An Effect on Braking Force for Degradation of Rail Surface in the Urban Railway (도시철도에서 열차제동하중이 레일표면 열화에 미치는 영향)

  • Yang, Tae-Kyoung;Oh, Hee-Wan;Sung, Deok-Yong;Choi, Jin-Yu;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.2135-2146
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    • 2011
  • The rail surface irregularity is generated severely by train braking effect in the section of station. The braking force increases slip rate and friction factors caused by wheel-rail contact points. It brings rail surface irregularity as well. In this study, interactions between wheel and rail were investigated using rolling contact fatigue theory and mechanism of rail degradation through fracture mechanics. For the more, the Von-Mises stress occurred on the rail due to the interaction between wheel and rail was analyzed using 3-D finite element method. The amounts of surface irregularity of rail were measured according to accumulated passing tonnage in urban railway in fields. Therefore, the maintenance of rail should be separated by running and braking sections to prevent RCF defects.

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Influence of PC Girder and Steel Girder on Stress Analysis for Maglev straight Track (PC Girder 및 Steel Girder가 자기부상열차 직선 궤도의 응력해석에 미치는 영향)

  • Rho K.S.;Lee J.M.;Cho H.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.653-656
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    • 2005
  • Maglev straight track composes of guide rail, back iron, power rail and girder. Above all, girder is important. So this study analyzes the influence of PC girder and steel girder on stress analysis fur Maglev straight track, and to study the stress analysis the finite element method is utilized.

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Forced Vibration Modeling of Rail Considering Shear Deformation and Moving Magnetic Load (전단변형과 시간변화 이동자기력을 고려한 레일의 강제진동모델링)

  • Kim, Jun Soo;Kim, Seong Jong;Lee, Hyuk;Ha, Sung Kyu;Lee, Young-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.12
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    • pp.1547-1557
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    • 2013
  • A forced vibration model of a rail system was established using the Timoshenko beam theory to determine the dynamic response of a rail under time-varying load considering the damping effect and stiffness of the elastic foundation. By using a Fourier series and a numerical method, the critical velocity and dynamic response of the rail were obtained. The forced vibration model was verified by using FEM and Euler beam theory. The permanent deformation of the rail was predicted based on the forced vibration model. The permanent deformation and wear were observed through the experiment. Parametric studies were then conducted to investigate the effect of five design factors, i.e., rail cross-section shape, rail material density, rail material stiffness, containment stiffness, and damping coefficient between rail and containment, on four performance indices of the rail, i.e., critical velocity, maximum deflection, maximum longitudinal stress, and maximum shear stress.

Nonlinear earthquake response analysis of CWR on bridge considering soil-structure interaction. (지반-구조물 상호작용을 고려한 교량상 장대레일의 비선형 지진응답해석)

  • Shin Ran Cheol;Cho Sun Kyu;Yang Shin Chu;Choi Jun Seong
    • Proceedings of the KSR Conference
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    • pp.733-738
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    • 2004
  • Recently continuous welded rail is generally used to ensure running performances and to overcome the problems such as structural vulnerability and fastener damage at the rail expansion joint. Though the use of continuous welded rail on bridge has the advantage of decreasing the vibration and damage of rail, it still the risk of buckling and breaking of rail due to change of temperature, starting and/or breaking force, axial stress concentration and so on. So, VIC code and many methods has been developed by researchers considering rail-bridge interaction. Although there are many research concerning stability of continuous welded rail about temperature change on bridge and starting and/or breaking force, the study of continuous welded mil for earthquake load is still unsufficient. In this study, the nonlinear seismic response analysis of continuous welded rail on bridge considering soil-structure interaction, geotechnical characteristic of foundation and earthquake isolation equipment has been performed to examine the stability of continuous welded rail.

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Embedded Rail Track on the LRT(Tram) (레일 매립궤도의 특성과 노면철도에 적용 가능성에 관한 연구)

  • Lee Ki-Seung;Kim Sung-Chil;Beak Jin-Ki;Go Dong-Chun
    • Proceedings of the KSR Conference
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    • pp.394-399
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    • 2005
  • Embedded rail track can be described as a track structure that is completely covered within pavement. Rail supported continually on a concrete slab or concrete plinth. There are many kinds of types such as non-resilient track and resilient track, super resilient embedded track (floating slab). Embedded rail track is generally the standard for light rail transit routes because this track has many advantages such as reducing noise, maintenance cost and weight of track. In this paper, decision of track profile is restricted by the optimum levels of the flangeway and the gap between the rail head and the pavement surface of depressing tread zone. By result of this study, embedded rail track can reduce corrosion of rail, internal stress and rail deflection.

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Evaluation of Residual Stress of railway wheel by rolling contact (차륜/레일 접촉에 의한 차륜의 잔류응력 평가)

  • Seo, Jung-Won;Goo, Byenug-Choon;Chung, Heung-Chai
    • Journal of the Korean Society for Railway
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    • v.6 no.2
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    • pp.142-148
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    • 2003
  • A wheel and axle failure can cause a derailment with its attendant loss of life and property. The service conditions of railway vehicles have become severe in recent years due to a general increase in operating speeds. Damages of railway wheel are a spatting by wheel/rail contact and thermal crack by braking heat etc. One of the main source of damage is a residual stress. therefore it is important to evaluate exactly. A Residual stress of wheel is formed at the process of heat treatment when manufacturing. it is changed by contact stress developed by wheel/rail contact. Distributions of residual stress vary according to a magnitude of wheel load, a magnitude of friction when acceleration and deceleration. The objective of this paper is to estimate the influence of wheel motion on the residual stress distribution in the vicinity of the running surface.

Simulation of Ratcheting in Wheel-Rail Contact (차륜-레일 구름접촉에 의한 라체팅 모델링)

  • Goo, Byeong-Choon
    • Journal of the Korean Society for Railway
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    • v.11 no.3
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    • pp.311-316
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    • 2008
  • Ratcheting is a cyclic accumulation of strain under a cyclic loading. It is a kind of mechanisms which generate cracks in rail steels. Though some experimental and numerical study has been performed, modeling of ratcheting is still a challenging problem. In this study, an elastic-plastic constitutive equation with non-linear kinematic hardening equation was applied. Contact stresses in wheel-rail were analyzed. Under the tangential stress of the contact stresses, a cyclic stress-strain relation was obtained by using the model. A constant ratcheting strain per cycle was accumulated.