• Title, Summary, Keyword: Rail stress

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Influence of Slab Length on behavior of Floating Slab Track by Rail-slab-isolator Longitudinal Interaction

  • Nguyen, Huan Ha;Jang, Seung Yup;Chung, Wonseok
    • International Journal of Railway
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    • v.5 no.4
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    • pp.163-166
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    • 2012
  • Many different types of floating slab track have been developed and installed around the world to reduce vibrations and noise originating in the surrounding environment. The main objective of this study is to examine the influence of slab length on behavior of floating slab track based on rail-slab-isolator interaction. The floating slab track is modeled by the connection between rail, slab, isolator, and slab mat in the transition zone. All elements were assembled in a simplified two-dimensional (2D) finite element model (FEM). The maximum length of FST is then investigated based on the maximum additional rail stress criterion as described in UIC 774-3R since no fully accepted design criteria for the slab length in FST systems currently exist.

Investigation of the Maintenance Criteria for the Rail Surface Defects in High-Speed Railways (고속철도 레일 표면 결함 관리기준에 관한 연구)

  • Yang, Sin-Chu;Jang, Seung-Yup
    • Journal of the Korean Society for Railway
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    • v.14 no.6
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    • pp.535-544
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    • 2011
  • The rail surface defects can cause the high impact load on the track and lead to the progress of the rail fatigue damage and the rail break. In case of the rail break, there is a great deal of risk for derailment, and thus the maintenance criteria for the rail surface defects are of great importance. In this study, using the dynamic train-track interaction analysis program, the impact wheel loads and rail bending stresses according to the depths of the surface defects have been calculated with the input data of the rail surface irregularities measured at 43 spots with surface defects in the ballasted track of high-speed railway. Considering the irregularity of track geometry, the allowable limits of wheel load and rail bending stress have been set, and the maintenance criteria for the rail surface defects was suggested by analyzing the relationship of the maximum values of wheel load and rail bending stress versus depth and width of rail surface defect. The analysis results suggest that the allowable depth of the surface defect is determined approximately 0.2mm from the limit of the impact wheel load.

Fatigue Crack Growth Behavior for Rail Steel under Mixed Mode Variable Amplitude Loading (혼합모드 변동하중하에서 레일강의 피로균열 진전거동)

  • Sohn, Kyoung-Ju;Seo, Young-Bum;Kim, Chul-Su;Kim, Jung-Kyu
    • Proceedings of the KSME Conference
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    • pp.261-266
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    • 2003
  • The growth behavior of the transverse crack, which was one of the most dangerous damages of rail defects, was investigated under mode I and mixed mode loading in rail steel. In the case of variable amplitude loading, the fatigue crack growth behavior was discussed using characteristic stress intensity factor ranges ${\Delta}_{rms}$. In addition, characteristic comparative stress intensity factor ranges ${\Delta}_{V,rms}$ was proposed to evaluate the quantitative effects of the variable amplitude under mixed mode loading. As a result, crack growth rate under variable amplitude loading was faster than that under constant amplitude loading.

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Analysis of the Residual Stress Produced by non-metallic Inclusions during Rail Manufacturing Process (레일의 제조공정에서 비금속 개재물에 의한 레일의 잔류응력 해석)

  • 구병춘;정우현;이희성;서정원
    • Proceedings of the KSR Conference
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    • pp.352-357
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    • 1999
  • During the cooling process of rail, residual stresses are produced due to the difference of the coefficients of thermal expansion between rail and inhomogeneous non-metallic inclusions such as sulphides and oxides. A micro-mechanical approach is used to obtain the stresses in the inclusions and matrix, After obtaining the stress of an elliptical inhomogeneous inclusion in an infinite domain, average stresses of randomly distributed spherical inclusions are obtained by use of Mori-Tanaka's self consistent method. The magnitude of the calculated residual stress is near to the yield stress of the matrix in case of the spherical inclusions.

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Analysis of Contact Stress with Partial Slip in Wheel-rail Rolling Contact (차륜-레일 구름접촉 시 슬립율에 따른 접촉응력의 변화 해석)

  • Lee, Dong-Hyong;Seo, Jung-Won;Kwon, Seok-Jin;Choi, Ha-Yong;Kim, Chul-Jae
    • Proceedings of the KSR Conference
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    • pp.643-648
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    • 2011
  • Fatigue crack in most rails take place by rolling contact between wheel and rail in railway industry. Therefore, it is critical to understand the rolling contact phenomena, especially for the three-dimensional situation. In this paper the steady-state rolling contact problem of KTX wheel and rail (UIC60) has been studied with three-dimensional finite element analysis. The variation of contact pressure and contact stresses on rolling contact surface were obtained using the finite element method. The three-dimensional distribution of contact stresses on the contact surface are investigated. Results show that the distribution of shear stress and contact stress (von Mises) on the contact surface varies rapidly as a result of the variation of stick-slip region. The contact stress at the leading edge is greater than at the trailing edge because of stick and slip phenomena.

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Evaluation of Rail Fatigue Life by Rail Grinding in the High Speed Railway (레일연마에 따른 고속철도 레일 피로수명 평가)

  • Park, Won-Seo;Lim, Hyung-Jun;Park, Yong-Gul;Sung, Deok-Yong;Kang, Yoon-Suk
    • Proceedings of the KSR Conference
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    • pp.783-792
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    • 2011
  • The control of rail surface irregularity is very important for the high speed train service in the high speed rail. In order to manage it, initial, preventative, and maintainable rail grinding have been performed and among them, preventative rail grinding conducts in every each year. This study carried out the field test for dynamic track response according to rail surface irregularity comparing before and after rail grinding. In addition, the change of dynamic track responses according to rail grinding was analyzed and the fatigue life was estimated though Rainflow Counting Method and RMC Equivalence Stress. Therefore, it suggested that rail fatigue life should be increased by rail grinding, because amount of impact occurred on track is decreased by getting rid of rail surface irregularity.

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Development of Design Chart for Investigating an Additional Rail Stress and Displacement on CWR(II) - Design Chart for Railway Bridge of Conventional Line (장대레일 부가축력 및 변위 검토를 위한 설계차트 개발(II) - 일반철도 교량 설계차트)

  • Choi, Il-Yoon;Lim, Yun-Sik;Yang, Sin-Chu;Choi, Jin-Yu
    • Journal of the Korean Society for Railway
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    • v.12 no.4
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    • pp.574-581
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    • 2009
  • Displacement of the bridge and additional rail stress due to interaction between track and bridge should be limited to the design criteria. Interaction analysis was conducted to investigate the displacement and additional rail stress on CWR in railway bridge of conventional line. Particularly, various parameters affecting interaction phenomena were taken into account in the analysis to enhance an applicability. These parameters included configuration of structure, stiffness of deck and support, steel/concrete bridge, ballast/concrete track and FM/MFM type etc. The results were presented in the form of the design chart which could be useful in preliminary design of the bridge.

The Parametric Study Effecting on the Fatigue Life of Rail on High Speed Railway (고속철도 레일의 피로수명에 영향을 미치는 매개변수 연구)

  • Park, Yong-Gul;Kang, Yoon-Suk;Go, Dong-Chun;Sung, Deok-Yong
    • Journal of the Korean Society for Railway
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    • v.12 no.3
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    • pp.396-404
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    • 2009
  • With developing the next generation high speed railway, there need to be plans to make sure of running safety though researchs on the crack and break of rail by rolling contact fatigue. Therefore, this study performed the parametric analysis effecting on the fatigue life of rail using simplified equations. It analyzed the internal stress of rail according to the track quality, train velocity, wheel radius, track stiffness, sleeper space, wheel load. For the more, via the finite element method, it analyzed shear force on the rail head which could be changed by the early length of crack, angle of crack and temperature. As a result, this study continued the main parameter effecting on the fatigue life of rail.