• Title, Summary, Keyword: Equivalent Conicity

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Analysis on the Influence of Wheel/Rail Geometric Parameters on the Equivalent/Conicity (차륜/레일 기하학적 인자에 의한 등가답면구배 영향 분석)

  • Hur Hyun-Moo;Kwon Sung-Tae
    • Journal of the Korean Society for Railway
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    • v.8 no.5
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    • pp.490-494
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    • 2005
  • The geometric parameters between wheel and rail change wheel/rail contact geometry characteristics, and this influence dynamic behavior of rolling stock. So, the selections of optimum geometric parameters between wheel and rail is important for planning of railway system. In this study, we have analyzed the influence of geometric parameters like wheel flange-back distance, gage, and rail inclination on the equivalent conicity relating to dynamic behavior. The analyses show the following results. The widening of wheel flange-back distanc, the decrement of gage increase the equivalent conicity and the increment of rail inclination show the sharp change of the equivalent conicity.

A study on the influence of wheel/rail geometric parameters to equivalent conicity (차륜/레일 기하학적 인자의 등가답면구배에 미치는 영향)

  • Hur Hyun-Moo;Kwon Sung-Tae;Kim Hyung-Jin
    • Proceedings of the KSR Conference
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    • pp.430-434
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    • 2004
  • The geometric parameters between wheel and rail change wheel/rail contact geometry characteristics, and this influence dynamic behavior of rolling stock. So, the selections of optimum geometric parameters between wheel and rail is important for planning of railway system. In this study, we have analyzed the influence of geometric parameters like wheel flange-back distance, gage, and rail inclination to the equivalent conicity relating dynamic behavior. The analyses show the following results. The widening of wheel flange-back distance increase the equivalent conicity, the widening of gage, rail inclination 1/20 compared with rail inclination 1/40 decrease the equivalent conicity.

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Analysis on the Running Stability of Rolling-stock according to Wheel Profile Wear (차륜답면형상 마모에 따른 차량 주행안정성 영향 분석)

  • Hur, Hyun-Moo;You, Won-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.5
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    • pp.551-558
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    • 2011
  • To analyze the effect of wear of wheel profile on the running stability of rolling-stock, theoretical and experimental studies were conducted on the profiles used in conventional lines. In experiment using 1/5 scale model to verify the results of the theoretical analysis, the test results of the critical speed for worn wheel profile samples show similar trend. In case of the conical type wheel profile(Profile 40), the equivalent conicity is increased with flange wear. But in case of the arc type wheel profile(Profile 20h), the equivalent conicity is decreased with flange wear. And the critical speed of the bogie was inverse proportion to the equivalent conicity. It is shown that the variation of the critical speed with the wheel wear could be changed according to the design concept and wear pattern of wheel profile. Results of the theoretical and experimental studies are discussed here.

Design Method of Railway Wheel Profile with Objective Function of Eqivalent Conicity (등가답면구배를 목적함수로 하는 차륜답면형상 설계기법)

  • Hur, Hyun-Moo;You, Won-Hee;Park, Joon-Hyuk;Kim, Min-Soo
    • 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.

The Analysis on the Carbody Vibration of Wheel Profiles for KTX (경부고속차량의 차륜답면 형상별 차체진동 분석)

  • Lee Chan-Woo;Kim Jae-Chul;Moon Kyeong-Ho
    • Proceedings of the KSR Conference
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    • pp.730-733
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    • 2003
  • In this study, it have been measured the vertical and lateral vibrations of car bodies which have an equivalent conicity of 1/20 and 1/40. Based on the measured data, it is revealed that the wheel, XP-50, which has the equivalent conicity of 1/20 causes the better riding comfort of KTX.

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Stability Evaluation of the Railway Bogie According to the Tread Inclination of Wheel Profile Using Scale Model (축소모델을 이용한 차륜답면형상 답면구배에 따른 안정성 평가)

  • Hur, Hyun-Moo;You, Won-Hee;Kim, Nam-Po;Park, Tae-Won
    • 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.

A Study on the Ride Quality Enhancement of the High-speed Electric Multiple Unit (동력분산형 고속열차의 승차감 개선에 관한 연구)

  • Jeon, Chang-Sung;Kim, Sang-Soo;Kim, Seog-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.561-567
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    • 2018
  • This study was carried out to improve the ride quality of high-speed electric multiple unit. Through dynamic analysis of the HEMU-430X, the range of the equivalent conicity with a critical speed of 300 km/h was between 0.05 and 0.25. The initial adopted wheel profile of HEMU-430X was S1002. The equivalent conicity of S1002 with the mileage of more than 40,000 km was about 0.033 and it was confirmed that XP55 is more suitable for stable operation because XP55 has the equivalent conicity of over 0.061. In order to improve ride quality of high-speed electric multiple unit, the change of installation angle of the yaw damper was suggested from $7.35^{\circ}$ to $0^{\circ}$. From sensitivity analysis and optimization, the air spring lateral and vertical stiffness was suggested to be reduced by 30% and the secondary vertical and lateral damper damping coefficient was increased by 50%. By applying this, it was expected that the car body acceleration could be improved by about 20% on average. The HEMU-430X's yaw damper installation angle was changed to $0^{\circ}$ and the damping coefficient of the lateral damper was increased by 30%. When the test run was carried out at the speed of 300 km/h on the Kyungbu high-speed line, the vehicle lateral acceleration had improved by 34.3%. The effect of additional improvement measures proposed in this paper will be tested in the on track test. The riding quality improvement process used in this study can be used to solve ride quality problems that can occur in commercial operation of high-speed electric multiple unit in the future.

A Study on the Lateral Vibration Reduction of the High-speed Electric Multiple Unit (동력분산형 고속열차의 횡방향 진동저감에 관한 연구)

  • Jeon, Chang-Sung;Park, Joon-Hyuk;Kim, Sang-Soo;Kim, Seog-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.12
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    • pp.797-803
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    • 2019
  • This study was carried out to reduce the lateral vibration of high-speed electric multiple units. In the study, the high-speed electric multiple unit prototype (HEMU-430X) has a high lateral vibration at low equivalent conicity regardless of the wheel profiles (XP55, GV40, S1002). As wheel wear progresses and the equivalent conicity increases, the lateral vibration tends to decrease. The reason is that a combination of the suspension characteristics causes the body and bogie to resonate at a frequency of 1.4 Hz when the equivalent conicity is low, resulting in body hunting. An investigation of the lateral vibration of overseas high-speed trains showed that a decrease in the hydraulic stiffness of the yaw damper could improve the vibration. The series stiffness of the yaw damper is a combination of the hydraulic stiffness and elastic joint. In this study, an attempt was made to improve the lateral vibration by lowering the stiffness of the elastic joint. The series stiffness of the adjusted yaw damper was approximately 60% compared to the original one. The on track test results showed improvement in the lateral vibration for both running directions. The vibration reduction method of this study can be used for EMU-250 and EMU-320 in future commercial operations.

Compatibility Analysis of Wheel/Rail Profile on Conventional Railway (기존철도 차륜/레일형상의 적합성 분석)

  • Hur, Hyun-Moo;Seo, Jung-Won;Chung, Heung-Chai;Goo, Dong-Hoe
    • Proceedings of the KSME Conference
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    • pp.934-939
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    • 2004
  • Railway wheel/rail contact conditions have an influence on dynamic behavior of rolling stock. If there are problems of incompatibility between wheel and rail, damages like wheel wear, wheel spalling, rail wear, etc are occurred. Especially wheel and rail profiles are important factor of vehicle curving performance, so compatibility study between wheel and rail has to be carried out preferentially, In this study, we have analyzed the compatibility between wheel and rail of KNR conventional line to improve the maintenance efficiency of wheel and rail. Thus we showed the results relating to wheel/rail geometric contact, vehicle running performances as the change of wheel/rail combination.

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