• Title, Summary, Keyword: Rail Stability

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Sensitivity of the Continuous Welded Rail and the Fastener on the Track Stability (궤도 안정성에 대한 장대레일과 체결구의 민감도)

  • Han, Sang Yun;Park, Nam Hoi;Lim, Nam Hyoung;Kang, Young Jong
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.4A
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    • pp.719-726
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    • 2006
  • The use of CWR track not only reduces the track maintenance cost, but increase the life cycle of track components. Therefore, the use of the CWR track has increased consistently in the worldwide. As the use of CWR increases in track structures, derailing disasters associating with track buckling also increase in great numbers due to high compressive thermal stress in the summer. Among many CWR parameters, the influence of the sectional properties of the rail was investigated on the stability of CWR track in this study. Also, the sensitivity of the broken fastener and the stiffness of the fastener system such as the translational and rotational stiffness was investigated.

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A Study on Optimum Spacing of Rail Joint for Personal Rapid Transit(PRT) Track System (소형무인경전철 레일이음매의 적정 간격 산정 연구)

  • Choi, Jung-Youl;Kim, Pil-Soo;Chung, Jee Seung
    • The Journal of the Convergence on Culture Technology
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    • v.4 no.3
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    • pp.213-220
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    • 2018
  • The objective of this study was to estimate the optimum spacing of rail joint for a personal rapid transit(PRT) track system, and to compare the results with the normal rail and rail joint by performing the finite element analysis(FEA) and field measurements using actual vehicles. Based on the FEA and field measurement results compared, the optimum spacing of the rail joints was calculated to be maximum of 1.20m based on the rail displacement. The vertical displacement of the normal rail was higher than that of the rail joint at a spacing of 1.0m, but it was considered that the vehicle riding performance and serviceability of track would be improved in terms of the stability of the train due to similar to rail defection between normal rail and rail joint. Also, because of the proposed rail joint spacing in this study was longer than the current rail joint spacing, the economic effect would be expected by decreasing the amount of sleepers.

Air-Gap Signal Treatment based Fuzzy Rule in Rail-Joint (Rail-Joint에서 퍼지룰을 기반으로하는 공극신호처리법)

  • Sung, H.K.;Jho, J.M.;Lee, J.M.;Bae, D.K.;Kim, B.S.;Shin, B.C.
    • Proceedings of the KIEE Conference
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    • pp.1071-1072
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    • 2006
  • Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

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A Study on the rail-transport operation control for railway embankment under rainfall (강우시 철도성토사면의 열차운전규제기준에 관한 연구)

  • 김현기;박영곤;신민호;김수삼
    • Proceedings of the KSR Conference
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    • pp.514-519
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    • 2001
  • There are a close relationship between natural disasters and train safety. So it is very important to guaranty train safety using reasonable rail-transport operation control against disasters. Therefore, based on the past record of rainfall at failure, rail-transport operation control for railway embankment under rainfall was set up. After slope check list at home and abroad had been analyzed, new slope check list was suggested and site investigations were carried out using this check list. In order to evaluate the stability of railway slopes under rainfall, explanatory variables and subordinate variables were selected for multi-variate analysis and critical rainfall was defined by statistical process. Rail-transport operation control including regional and geological properties was suggested by analyzing the critical rainfall and rail-transport operation control in other country, and this will be a good tool to control train speed under rainfall and to secure train safety.

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On bending, buckling and vibration of graphene nanosheets based on the nonlocal theory

  • Liu, Jinjian;Chen, Ling;Xie, Feng;Fan, Xueliang;Li, Cheng
    • Smart Structures and Systems
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    • v.17 no.2
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    • pp.257-274
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    • 2016
  • The nonlocal static bending, buckling, free and forced vibrations of graphene nanosheets are examined based on the Kirchhoff plate theory and Taylor expansion approach. The nonlocal nanoplate model incorporates the length scale parameter which can capture the small scale effect. The governing equations are derived using Hamilton's principle and the Navier-type solution is developed for simply-supported graphene nanosheets. The analytical results are proposed for deflection, natural frequency, amplitude of forced vibration and buckling load. Moreover, the effects of nonlocal parameter, half wave number and three-dimensional sizes on the static, dynamic and stability responses of the graphene nanosheets are discussed. Some illustrative examples are also addressed to verify the present model, methodology and solution. The results show that the new nanoplate model produces larger deflection, smaller circular frequencies, amplitude and buckling load compared with the classical model.

Investigation of Microstructure and Mechanical Properties of KR60 Rail (KR60 레일의 미세조직과 기계적 물성 평가)

  • Choi, Wookjin;Cho, Hui Jae;Yun, Kyung-Min;Min, Kyung-Hwan;Lim, Nam-Hyoung;Lee, Soo Yeol
    • Korean Journal of Materials Research
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    • v.27 no.12
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    • pp.652-657
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    • 2017
  • The use of continuous welded rail is increasing because of its many advantages, including vibration reduction, enhanced driving stability, and maintenance cost savings. In this work, two different types of continuous welded rails were examined to determine the influence of repeated wheel-rail contact on the crystal structure, microstructure and mechanical properties of the rails. The crystal structure was determined by x-ray diffraction, and the microstructure was examined using optical microscopy and scanning electron microscopy. Tensile and microhardness tests were conducted to examine the mechanical behaviors of prepared specimens taken from different positions in the cross section of both newly manufactured rail and worn rail. Analysis revealed that both the new and worn rail had a mixed microstructure consisting of ferrite and pearlite. The specimens from the top position of each rail exhibited decreased lamella spacing of the pearlite and increased yield strength, ultimate tensile strength and hardness, as compared with those from other positions of the rail. It is thought that the enhanced mechanical property on the top position of the worn rail might be explained by a mixed effect resulting from a directional microstructure, the decreased lamella spacing of pearlite, and work hardening by the repeated wheel-rail contact stress.

Running Stability Analysis on the Tail Car of KTX (KTX 후미 차량의 주행 안정성 해석)

  • Lee Seung-Il;Choi Yeon-Sun
    • Proceedings of the KSR Conference
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    • pp.350-355
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    • 2005
  • The running stability and safety of a railway vehicle depends on the design characteristics and the contact condition between wheel and rail. In this paper, numerical simulations using ANSYS and ADAMS were done on the basis of the experimental observations. The results show that 0.6 Hz of the tail car motion is due to the natural mode of car combination of the KTX. The effects of the conicity of wheel and the lateral stiffness of the secondary suspension on the running stability were analyzed numerically using ADAMS/RAIL. The results also show 0.6 Hz as like the experimental observations. And the adoption of the wheel of GV40(${\lambda}=0.025$) brought the sway motion at the tail cars, but XP55(${\lambda}=0.055$) did not when the secondary lateral stiffness of the KTX was greater than 0.3 MN/m.

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Longitudinal Static Stability of Wings Flying Over Nonplanar Ground Surfaces (비평면 지면효과를 받는 날개들의 종방향 정안정성)

  • 김학기;조진수;한철희
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.7
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    • pp.12-17
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    • 2006
  • Longitudinal static stability and steady aerodynamic characteristics of wings flying over nonplanar ground surfaces (rail and channel) are investigated using the boundary-element method. For a channel with it's fence higher than the wing height, the lift and the nose-down pitching moment increase as the gap between the wingtip and the fence decreases. For a rail with it's width wider than the wing span, the lift and the nose-down pitching moment increase as the rail height decreases. Longitudinal static stability of a single wing flying over nonplanar surfaces is worse than the case of the flat ground. In case of tandem wings, longitudinal static stability of the wings flying over the channel is better than the case of the flat ground. It is believed that the present results can be applied to the conceptual design of high-speed ground transporters.

Air-gap Signal Treatment at rail-joint in Maglev System (자기부상시스템에서 레일 이음매 통과시 공극 처리방법)

  • Sung, H.K.;Jho, J.M.;Lee, J.M.;Bae, D.K.;Kim, B.S.;Kim, D.S.;Shin, B.C.
    • Proceedings of the KIEE Conference
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    • pp.310-312
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    • 2006
  • Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

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Numerical Analysis of the Roadbed Settlement beneath Rail Joint Induced by Tilting-Train Loading (틸팅차량 하중에 의한 레일 이음매 하부 노반침하에 대한 수치 해석적 분석)

  • Jeon, Sang-Soo;Eum, Gi-Young;Kim, Jae-Min;Jung, Du-Hwoe;Han, Sung-Dae
    • Journal of Korean Society of Hazard Mitigation
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    • v.6 no.4
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    • pp.7-14
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    • 2006
  • The tilting-train being operated in pre-existing rail road has a different running mechanism compared to currently operated trains. Therefore, it needs to investigate the evaluation of the track performance, the stability of the tilting-train in operating condition, and the stability of the roadbed. In this study, when the tilting train is operated in the rail joint with the allowable velocity limited by the track performance and the stability of the tilting-train, the settlement of the roadbed has been evaluated by using numerical analysis. The loading on the ground surface generated by the operating tilting-train generates the settlement of the roadbed. The settlement induced by the tilting-train loading has been compared to the allowable settlement and the factor of safety defined by the ratio of the allowable settlement to the settlement generated by the applied loading is evaluated.