• International Journal of Korean Welding Society
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• v.4 no.1
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• pp.1-9
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• 2004

Continuously welded tracks, first introduced on train lines, are being used increasingly in Europe. And the different arc welding methods are only used on minor lines, private tracks and in the manufacturing of switches and crossings. Mobile flash butt welding belongs the future in rail welding on side if new tracks have to be erected. The following contribution reviews the processes available, usual test methods for welded rail joints and various applications.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.369-375
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• 2009

The Periodic replacements criterion of rail is calculated on the basis of the research result of RTRI in Japan. 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 order to establish the periodic replacements criterion of CWR, this study measured the rail surface irregularity according to the accumulated passing tonnage, the types of track system and welding. Therefore, it is analyzed that the gas pressure welding is the worst one of the others. In addition, it is analyzed that the rail surface irregularity growth rate in ballast track is about $0.02{\sim}0.03mm$/100MGT and its in concrete track is about $0.005{\sim}0.02mm$/100MGT Finally, the result of this study is able to use the basis data to establishing the periodic replacements criterion of CWR considering rail grinding.

• International journal of steel structures
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• v.18 no.5
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• pp.1617-1630
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• 2018

The crucial differences between conventional rail with split-type connectors and continuous welded rails are axial stress in the longitudinal direction and stability, as well as other issues generated under the influence of loading effects. Longitudinal stresses generated in continuously welded rails on railway bridges are strongly influenced by the nonlinear behavior of the supporting system comprising sleepers and ballasts. Thus, the track structure interaction cannot be neglected. The rail-support system mentioned above has properties of non-uniform material distribution and uncertainty of construction quality. The linear elastic hypothesis therefore cannot correctly evaluate the stress distribution within the rails. The aim of this study is to apply the nonlinear finite element method using the nonlinear coupling interface between the track and structural model and to illustrate the welded rail behavior under the loading effect and uncertain factors of the ballast. Numerical results of nonlinear finite analysis with a three-dimensional solid and frame element model are presented for a typical track-bridge system. A composite plate girder, modeled by solid and shell elements, is also analyzed to consider the behavior of the welded rail. The analysis result showed buckling under the independent calculations of load cases, including 'temperature change', 'bending of the supporting structure', and 'braking' of the railway vehicle. A parametric study of the load combination method and the loading sequence is also included in this analysis.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.64-71
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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, based on the results of bending fatigue tests of rail and results of measuring tests in situ of rail bending stress, this study estimated the bending fatigue life of welded rail in concrete track, adopting a Haibach's rule. The bending fatigue life of CWR considered the rail surface irregularity, train speed and the S-N curve by types of rail welding. In addition, this study estimated it for the fracture probability 1%, 0.1%, 0.01%. Therefore, this study proposed bending fatigue life of CWR in concrete track.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.59-66
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• 1998

This paper presents friction and wear related results of thermite and gas pressure welded rails under various environmental contact conditions. A welded rail which is fabricated by thermite welding and gas pressure one has been tested over full range of test conditions in a pin-on-disk wear testing machine. The results show that the friction coefficient and wear rates of a welded rail are heavily dependent on the contact pressures and sliding environments for two welding methods such as thermite and gas pressure weldings.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.119-125
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• 2000

In this study, field measurements and analysis of vibration before and after the installation of continuously welded rail were performed. The vibration data obtained at the same locations before and after were analyzed to find out the characteristics of vibration level. The component of train-induced impulsive vibration at the rail joints varies depending upon the distance from the source, however mostly low frequency vibration which propagates long distance causes the problems of vibration. Even though it is expected that there may be certain degree of discrepancy in the amount of reduction in vibration depending upon site ground conditions, it was found that installation of continuously welded rail shows reduction in train-induced vibration.

• International Journal of Railway
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• v.3 no.4
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• pp.126-133
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• 2010

The thermal buckling analysis of curved continuous welded rail (CWR) is studied for the lateral buckling prevention. This study includes a thermal buckling theory which accounts for both thermal and vehicle loading effects in the evaluation of track stability. The parameters include rail size, track lateral resistance, track longitudinal and torsional stiffnesses, initial misalignment amplitude and wavelength, track curvature, tie-ballast friction coefficient and truck center spacing. Parametric studies are performed to evaluate the effects of the individual parameters on the upper and lower critical buckling temperatures. The results show that the upper critical buckling temperature is highly affected by the uplift due to vehicle loads. This study provides a guideline for the improvement of stability for dynamic buckling in curved CWR track.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1469-1470
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• 2010

• Proceedings of the KSR Conference
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• 2007.11a
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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.