• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.524-529
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• 2008

The damaged wheel in railway vehicle would cause a poor ride comfort, a rise in the maintenance cost and even fracture of the wheel, which then leads to a tremendous social and economical cost. The defect initiation and crack propagation in wheel may result in the damage of the railway vehicle or derailment. Therefore, it is important to evaluate the characteristics of the wheel tread. In the present paper, the characteristics of wheel tread based on contact positions, running distance and brake pattern are evaluated. The result shows that the damaged wheel tread is remarkably depended on the contact positions between wheel and rail.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.192.1-192.1
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• 2005

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.473-479
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• 2007

Lateral vibration at the tail of KTX train was found during the acceptance test. In order to settle the problem of lateral vibration, the wheel conicity was changed 1/40 to 1/20. However, we should evaluate the running safety of vehicle with 1/20 wheel conicity because modification of wheel conicity may cause the running performance to be worse and critical speed to reduce. In this paper, we calculate critical speed of KTX bogie as wheel conicity increase and analyze the running safety for KTX that has 20 car trainset formation using VAMPIRE. and compare with the test results of KHST to validate analysis results on high speed line. A analysis results show that critical speed of 0.3 wheel conicity is over 375km/h and curving performance of 1/20wheel conicity is better than 1/40. Also, we examinate the running performance of KTX to check out possibility to increase speed of KTX on conventional line. A analysis results show that it is possible to increase up to 10% the speed of KTX on tangent line but KTX on a curved line should be operated with the speed of conventional train.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.95-103
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• 2006

Wheel treads of E.M.U. are usually under a heavy thermal load by brake frictional heat between wheel and brake shoe and damaged by repeated thermal and mechanical loads. To examine the cause of wheel tread damage of E.M.U.'s in service running, a systematic approach has been used. This study is composed of three parts. Frictional heat analysis was conducted in the first part by finite element method. Two kinds of brake shoes in service were considered. In the second part, experimental study was carried out on a brake dynamometer. Temperatures were measured for the two brake shoes. And experimental study in service running E.M.U.'s was performed. Wheel and brake shoe temperatures were measured by using thermocouples and temperature indicating strips. Finally metallurgical characteristics were examined by a SEM/EDS and the cause of the wheel damage was analyzed. It seems that aggregated ferrous component is a main cause of the wheel tread damage.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.230-235
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• 2009

We have conducted an experimental study to analyze characteristics of the wheel profile wear and an influence of the wheel flange wear on the vehicle's vibration characteristics. In experiment with EMU, wheel profile wear is severe at the beginning of the commercial operation. In this stage, the variations of the wheel dimension parameters and equivalent conicity is changed rapidly. Along with a mileage of the test vehicle, the wear of the wheel flange is increased and also the vibration level of the car-body is increased. The peak-peak mean value of the body vibration is estimated as good level, but the level is approached at the limit of the good level as mileage increases. Especially, the peak-peak maximum value of the body vibration shows the distinct increase of vibration level.

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.1128-1133
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• 2006

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1099-1107
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• 2009

Numerical simulation and experimental study to evaluate the critical speed of the railway bogie according to the tread inclination of wheel profile were conducted using 1/5 scale model. It has been shown that the results of the critical speed analysis for the scale bogie model is very close to the test results using scale bogie model and the critical speed is decreased in proportion to the increase of equivalent conicity of wheel profile. Results of this study show that the scale model could be applied to research area relating to vehicle stability as an alternative to overcome the experimental problems caused by full scale test on the roller rig.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.259-263
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• 2004

The running safety of a railway vehicle depends on the design parameters and contact condition between wheel and rail. In this study, the effect of the conicity of wheel tread is analyzed using ADAMS/RAIL software on running situation. Modal analysis shows in 0.6 Hz natural frequency of lateral mode in fully arranged the KTX cars. The excessive vibration of the tail cars occurs in the 17th car as the speed and the stiffness of the secondary suspension increases, and especially for 1/40 conicity of the GV40 wheel. Also, the analysis shows that combination of wheel profile, GV40 for power cars and XP55 for passenger cars can reduce the lateral vibration of the tail cars.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.1007-1008
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.13-19
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• 2010

A design method of railway wheel profile with objective function of equivalent conicity considering wheel dimension constraint, two points contact problem between wheel and rail was proposed. New design method shows good results. New wheel profile generated from optimization process shows better dynamic performance compared with initial profile as the purpose of wheel profile design. And to verify the design method with testing the stability of new wheel profile, we conducted a critical speed test for new wheel profile using scale model applied scaling method of railway vehicle dynamics. The result of critical speed test show good agreement with that of numerical analysis. From the above results, it is seen that the design method with objective function of equivalent conicity is feasible and it could be applied to design new wheel profile efficiently.