• Title, Summary, Keyword: Rail stress

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Field Test to Investigate the Thermal Stress of Continuous Welded Rail on High Speed Railway Bridges in Summer Period (고속철도 교량상 장대레일의 하절기 온도응력 계측)

  • Kwark, Jong-Won;Choi, Eun-Suk;Chin, Won-Jong;Lee, Jung-Woo;Kim, Byung-Suk;Kang, Jae-Yoon
    • Journal of the Korean Society for Railway
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    • v.9 no.2
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    • pp.131-136
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    • 2006
  • Most modern railways, especially the high speed railway tracks, use continuous welded rail(CWR) for the less maintenance. For the CWR track has very few expansion joints, track buckling has always been an unpredictable event and it happens mainly by high compressive stress in rail in summer period. Therefore, it is important to understand the variation of rail stress induced by thermal loads which has direct influence on the rail buckling and stability of railway track. This paper describes the experimental investigation of the variation of rail temperature and stress in a high speed railway track on bridge structure. Field measurement was performed to examine the correlation between the rail temperature and rail stress on the Korean High Speed Railway line. Regression functions were derived from measured data to determine the rail stress f3r an arbitrary rail temperature varies from 20 to 50 degree Celsius.

Investigation of Thermal Stress of Continuous Welded Rail on High Speed Railway Bridge (경부고속철도 교량상 장대레일의 온도응력 계측 실험)

  • Kang, Jae-Yoon;Choi, Eun-Suk;Chin, Won-Jong;Lee, Jung-Woo;Kwark, Jong-Won;Kim, Byung-Suk
    • Proceedings of the KSR Conference
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    • pp.458-461
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    • 2007
  • Recently, the continuous welded rail(CWR) track has been used for less maintenance of the High-speed railway tracks. In case of CWR track, track buckling has always been an unpredictable event under the high compressive stress in rail. The behavior and stress state of CWR track is manily influenced by its thermal variations, and it is important to understand seasonal variations of rail temperature and stress to predict the track stability. This paper describes the in-site measurement for the rail temperature and rail stress, and the correlation between the rail temperature and stress was examined.

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Contact Characteristic and Stress Analysis of Wheel-Rail for Rolling Stock (철도차량용 휠과 레일의 접촉특성 및 응력 해석)

  • Sung, Ki-Deug;Yang, Won-Ho;Cho, Myoung-Rae;Kim, Cheol
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.5
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    • pp.148-156
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    • 2000
  • In this paper, we investigate contact characteristic of wheel-rail interface for rolling stock using the finite element method. Contact stress distribution due to the rail mounting slope is obtained in order to reduce the contact stress. Stress analysis of the rail, firstly, is performed one subjected to elliptical pressure based on Hertz theory. Secondly, we perform stress analysis of the rail subjected to contact stress obtained by this study. Results for the maximum shear stress, its location and the principal shear stress distribution are compared.

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Tribological Approach on the Stress Distribution of Wheel-Rail Contact (차륜과 레일 사이의 접촉응력에 관한 트라이볼로지적 해석)

  • 황재용;김기환;김청균
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.210-217
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    • 1997
  • This paper presents the numerical results of the stress analysis of wheel-rail contact problems. Two models which have straight and tapered(1:20) contact geometries between the wheelset and rail are analyzed using the finite element approach. From the simulation results we found that the tapered geometry of wheel-rail contact base line showed very stable contact stress distributions for a whole contact position between the wheel and rail in a curved rail section. The FEM computed results may present an optimized geometry of wheel-rail contact in a high-speed railway system.

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Finite Element Analysis on the Stress Distributions in Rail-Wheel Contacts of High Speed Trains (고속전철용 레일-휠 접촉에서 응력분포에 관한 유한요소해석)

  • 김청균;김기환
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.93-101
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    • 1997
  • The numerical results on the stress distributions of rail-wheel contact problems are presented for three models in a high-speed rail system. These models which have straight and tapered (1:40 and 1:20) contact geometries between the wheelset and rail are analyzed using the finite element approach. From the simulation results we found that the tapered geometry (1:20) of railwheel contact base line showed very stable contact stress distributions for a whole contact position between the wheel and rail in a curved rail section. The FEM computed results may present an optimized slope geometry of rail-wheel contact in a high-speed railway system.

A Study on the Contact Behavior of Stress-Displacement Characteristics for an Inclined Rail-Wheel Contact Mode (레일-휠의 접촉면 경사도에 따른 응력-변위량의 거동특성에 관한 연구)

  • 김청균
    • Journal of the Korean Society for Railway
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    • v.7 no.3
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    • pp.186-192
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    • 2004
  • Using the finite element method, rail-wheel contact model has been analyzed for mechanical loads due to passengers and payload of the train. This paper presents an investigation on how tapered wheel and inclined rail surfaces affect the contact stress and displacement of rail-wheel contacting surface under mechanical loads. For a numerical analysis, the tapered faces of the wheel are considered as 2.5% and 5.5%. And two models of the tilted rail are also considered as 40:1 and 20:1 at the bottom of the rail. The computed results based on the contact stress and displacement FE analysis indicate that the tilting ratio of the rail, 20:1 with a tapered face of the wheel, 2.5% may be more stable compared to that of 40:1 tilting model and 5.5% tapered wheel face.

Case of Application of Rail Temperature Detector for Track Management (궤도 관리를 위한 레일온도검지장치 설치 사례)

  • Chung, Sung-Hyun;Shin, Gil-Cheol;Kim, Gil-Soo
    • Proceedings of the KSR Conference
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    • pp.1362-1369
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    • 2007
  • Seoul Metro continuously converted the standard rail into continuous welded rail since the later part of 1990's, and currently, most of the sectors of the Seoul Metro are continuous welded rails. As the continuous welded rail is inhibited by the contraction and expansion force of the rail as well as rail-bed, this force is stored as the internal stress of the rail with the exception of portion of the both ends of the continuous welded rail. If the contraction and expansion of the rail is restricted, the internal stress, that is, the force in the direction of the axis, is proportional to the cross-sectional area of the rail. Therefore, with regards to the temperature changes, the internal stress changes in accordance with the type of rail, bolting apparatus, railroad tie and rail-bed. As such, the rail temperature becomes important data in securing the gap at the adjoining section of the rail in the standard rail section, and to determine the setting temperature for the continuous welded rail. In addition, it becomes basic data for maintenance of the track. Accordingly, this thesis introduces cases of installation of rail temperature detector in order to prevent and manage track defectiveness due to increase in rail temperature, and to utilize as basic data at the time of various construction and maintenance. Furthermore, this thesis aims to assist maintenance of track through systematic temperature management in the future by looking into means of its utilization.

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A study ell the residual stress in rail by the web saw-cut method (복부절단법에 의한 레일의 잔류응력에 관한 연구)

  • 서정원;구병춘;정우현
    • Proceedings of the KSR Conference
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    • pp.234-241
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    • 1999
  • Rails have residual stresses produced during manufacturing processes. The residual stresses play all important role on brittle fracture, fatigue strength and derailment by producing cracks in the web of rail. The web saw-cut test is a technique developed to measure the bulk longitudinal residual stress level. It is a simple mettled to estimate a stress intensity factor, $_{4}$ for a web crack by using the radii of curvature of the upper and lower portions of a cut rail. But according to this method, $_{4}$ varies along the rail length because the curvatures along tile rail length vary In this paper, tile residual stress was estimated by Finite Element Method and tile web saw-cut method. In addition tile variation of the residual stress with time was investigated.

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A study on the Shape Design Contact Characteristic of Wheel-Rail for Rollng Stock (2) (철도차량용 휠과 레일의 접촉특성 해석 및 형상설계에 관한 연구 (2))

  • 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.24 no.5
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    • pp.1238-1245
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    • 2000
  • One of the main causes of severe wear or crack initiation in wheel and rail is the contact stress due to wheel-rail contact. First, we obtain contact stress due to the rail mounting slope using the finite element method. Second, the shape design based on more reasonable contact stress analysis rather th~n a general Hertzian contact theory is investigated in order to reduce the contact stress. The optimum -design is performed using the simple 2-D finite element model and its results are verified by 311) finite element analysis.

The Evaluation of Safety and Remaining Life on Fracture and Fatigue in Rail Steel (철도레일의 파괴 및 피로에 대한 안전도평가 및 잔류수명계산)

  • 박용걸
    • Journal of the Korean Society of Safety
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    • v.10 no.2
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    • pp.120-128
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    • 1995
  • The fatigue failure of rail is a principal source of derailment accidents. The reduction of fatigue failures can be achieved by Intensive track maintenance and periodic safety assessments for the railway. For the safety assessments, it is required to have more accurate knowledge for fatigue behavior such as the crack initiation, propagation, crack growth rate and the remaining service life in rail. In this paper, the mean stress effects for the fatigue behavior of rail steel are studied. For this study, the fatigue test is conducted and some equations for fatigue evaluation are applied and compared. From the results, we can see that the fatigue crack growth rate is the more increased as the men stress Is the more increased, the mean stress effect is represented well by the combination of stress intensity factor range and maximum stress intensity factor and Crooker and Range's equation represented by ${\Delta}K, K_{max}$ is the best fit for fatigue evaluation and safety assessment of rail.

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