• Title, Summary, Keyword: Rail stress

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Interaction analysis of Continuous Slab Track (CST) on long-span continuous high-speed rail bridges

  • Dai, Gonglian;Ge, Hao;Liu, Wenshuo;Chen, Y. Frank
    • Structural Engineering and Mechanics
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    • v.63 no.6
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    • pp.713-723
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    • 2017
  • As a new type of ballastless track, longitudinal continuous slab track (CST) has been widely used in China. It can partly isolate the interaction between the ballastless track and the bridge and thus the rail expansion device would be unnecessary. Compared with the traditional track, CST is composed of multi layers of continuous structures and various connecting components. In order to investigate the performance of CST on a long-span bridge, the spatial finite element model considering each layer of the CST structure, connecting components, bridge, and subgrade is established and verified according to the theory of beam-rail interaction. The nonlinear resistance of materials between multilayer track structures is measured by experiments, while the temperature gradients of the bridge and CST are based on the long-term measured data. This study compares the force distribution rules of ballasted track and CST as respectively applied to a long span bridge. The effects of different damage conditions on CST structures are also discussed. The results show that the additional rail stress is small and the CST structure has a high safety factor under the measured temperature load. The rail expansion device can be cancelled when CST is adopted on the long span bridge. Beam end rotation caused by temperature gradient and vertical load will have a significant effect on the rail stress of CST. The additional flexure stress should be considered with the additional expansion stress simultaneously when the rail stress of CST requires to be checked. Both the maximum sliding friction coefficient of sliding layer and cracking condition of concrete plate should be considered to decide the arrangement of connecting components and the ultimate expansion span of the bridge when adopting CST.

A study on the refined resetting for the continuous weleded rail (장대레일 재설정 방법 개선 연구)

  • Kim, Woo-Jin;Jung, Chan-Mook;Min, Kyung-Ju
    • Proceedings of the KSR Conference
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    • pp.386-394
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    • 2007
  • Due to the transportability problems, long rail shall be from base rail unit, which is normally 100m for regular rail and 300m for high speed rail. After these rail units are transported from the fabricator to the site, the field weld would be performed.axial stresses in the long rail is mainly from the temperature differences at various locations the long rail. Also the gaps between each welds cause secondary axial stresses in the rail. In addition to these, re-welds the fractured rails, rail buckling, irregular rail vibration, rail twist also result innonuniform axial stresses in the rail. To obtain the rail buckling stability, the rail stresses shall be released due to the resetting of CWR. Traditionally two resetting of CWR methods have been applied, the one is rail heater and the other is rail tenser. these methods, the latter has been recommended because it has less limitation in the rail length and it is easier to minimized the force differences. But even in this method, the calculation is cumbersome and is not easy to find out the rail stress distribution itself.refined methodsxial stress resetting in the long rail is studied and this study be easily applied in the real construction. From this approach, more rational rail maintenance system can be expected.

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The Fatigue Life Evaluation of CWR based on the Rail Grinding (레일연마를 고려한 장대레일의 피로수명 평가)

  • Kong, Sun-Young;Sung, Deok-Yong;Park, Yong-Gul
    • Journal of The Korean Society of Civil Engineers
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    • v.35 no.5
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    • pp.1191-1198
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    • 2015
  • In this study, vehicle/track interaction analysis by the Saemaul powered vehicle was carried out. The prediction equation for the bending stress of rail was estimated using the rail bending stress by the rail surface irregularities at welds. Also, the fatigue analysis using a S-N curve of welds in the conventional railway was carried out. We estimated the fatigue life of CWR by the fracture probability. By the rail grinding, the fatigue life of CWR was evaluated in consideration to reduce the rail bending stress through removing the rail surface irregularities. Therefore, it presented the fatigue life of CWR according to the rail grinding execution plan in the conventional railway.

Calculating the Contact Stress Resulting from Lateral Movement of the Wheel on Rail by Applying Hertz Theory

  • Ashofteh, Roya Sadat
    • International Journal of Railway
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    • v.6 no.4
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    • pp.148-154
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    • 2013
  • This article has tried to review the maximum contact stresses in the contact area of the wheel and rail as a result of lateral movement of the wheel on rail by taking advantage from Hertz theory. Since wheel movement on rail is accompanied by lateral movement due to wheel profile conisity, so the contact point of wheel and rail is not constant and the contact stresses are therefore changeable in every single moment. Since the shape of rail profile and rail inclination, wheel diameter and the mechanical properties of the wheel and rail are effective on the stresses of contact area, these parameters have been studied by applying Hertz theory. This article aims to calculate the contact stresses in different parts on the wheel surface by using Hertz theory.

The Prediction Equation for Bending Stress of Rail in Concrete Track by the Linear Multiple Regression Analysis (중회귀분석을 통한 콘크리트궤도 레일 휨응력 예측식)

  • Sung, Deok-Yong;Lim, Hyoung-Jun;Lee, Dong-Wook;Kim, Bag-Jin;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.315-323
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    • 2010
  • It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In this study, it measured bending stress of rail according to the rail surface irregularity in the concrete track on the Seoul Metro. In addition, the relationship between rail surface irregularity and bending stress in concrete track is analyzed by results of the field test. Finally, this study clarified the relationship among bending stress(Y) of rail, train speed(U), rail surface irregularity(v, w) in concrete track. The result of this study is able to use the basis data to establishing the periodic replacements criterion of CWR.

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A Study on Estimation of Fatigue Life of Aged Continuous Welded Rail using the Field Test (현장측정을 통한 노후 레일의 피로수명 평가에 관한 연구)

  • Kong, Sun-Yong;Sung, Deok-Yong;Kim, Jun-Hyung;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.352-364
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    • 2007
  • It is essential to reduce track maintenance costs and to extend the periodic replacements of continuous welded rails based on accumulated passing tonnage. As recently train load decrease and rail joints wear down less, the periodic replacements of continuous welded rails can be extended. There are many kinds of rail damage like squat, head-check and corrugation. These can be taken nondestructive or naked eye test. So the periodic replacements of continuous welded rails based on accumulated passing tonnage were examine with focusing on a crack of rail bottom of continuous welded rail. Therefore, this study measure dynamic response of track by metro train load, it compute impact coefficient and track spring coefficient for estimating a condition of actual track system. Also, it is converted the measured stress waveform into stress frequency histogram by the rain-flow counting methods, and then the equivalence of stress is calculated. As apply s-n curve of a new welded rail, accumulated fatigue damage ratio of laid rail and remaining service lives is estimated. This study suggest a plan of the periodic replacements of continuous welded rails based on accumulated passing tonnage classified by the types of track system.

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Dynamic stress analysis of the railway vehicle using ADAMS/Rail and ADAMS/Durability (ADAMS/Rail과 ADAMS/Durability를 이용한 철도차량의 동응력 해석)

  • Cho Yon-Ho;Lee Kang-Wun;Park Gil-Bae;Choi Jung-Ho
    • Proceedings of the KSR Conference
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    • pp.573-578
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    • 2004
  • Rotem has chosen ADAMS/Rail as the next generation analysis tool, to improve the capability and accuracy of the analysis ability. The dynamic performances of the railway vehicle, which is designed and manufactured by Rotem, have been analyzed and simulated using ADAMS/Rail. In this paper, Dynamic stress of bogie frame on running track is analyzed and compared with the data of real vehicle test. It is performed using ADAMS/AutoFlex and ADAMS/Durability.

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An Analytic Study on the Contact Stress and Thermal Stress of Rails (레일의 라체팅에 미치는 접촉응력 및 열응력에 대한 해석적 연구)

  • Goo, Byeong-Choon;You, Won-Hee
    • Proceedings of the KSR Conference
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    • pp.767-774
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    • 2007
  • Even though a constant repeated load is applied, plastic deformation may cumulate. This kind of behavior is called ratcheting. Ratcheting may lead to cracks and finally to failure of the rail. Usually ratcheting occurs on high rails in curves. Ratcheting is influenced by residual stresses, wheel-rail contact stresses, thermal stresses due to wheel/rail rolling contact, shear strength of the rail, strain hardening behavior, etc. In this study, contact stresses and thermal stresses are examined. It is found their value is considerable compared to the maximum contact pressure.

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A Study on the Shape Design of Wheel-Rail for Rolling Stock (철도차량용 휠과 레일의 형상설계에 관한 연구)

  • Seong, Gi-Deuk;Yang, Won-Ho;Jo, Myeong-Rae;Heo, Seong-Pil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.11
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    • pp.2033-2039
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    • 1999
  • One of the main causes of severe wear or crack initiation in wheel and rail is the contact stress due to wheel-rail contact. In this paper, the shape design based on more reasonable contact stress analysis rather than a general Hertzian contact theory is investigated in order to reduce the contact stress. The optimal design is performed using the simple 2-D finite element model and its results are verified by 3-D finite element analysis.

Evaluation of Rail Fatigue and Bending Fatigue Considering Concrete Track Condition (콘크리트도상(STEDEF)의 선로조건을 고려한 레일휨응력 예측과 피로수명 산출)

  • Lee, Soo-hyung;Kang, You-song;Park, Yong-gul
    • Journal of the Korean Society for Railway
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    • v.20 no.5
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    • pp.658-667
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    • 2017
  • Rail is the main track component, playing the most important role in safe railways. For the sake of safety, it is strictly required to secure reliability against fatigue and destruction of rail. In this paper, by field measurement on concrete track, it is confirmed that the rail surface roughness and rail bending stress are linearly correlated with each other; the bending stress of rail can be presented as a function of train speed, track support stiffness, and rail surface roughness. The fatigue life of rail can be estimated by deriving the S-N curve through the fatigue test.