• Title/Summary/Keyword: Wheelset

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Calculation of Critical Speed of Railway Vehicle by Multibody Dynamics Analysis (다물체 동역학 해석방법을 이용한 철도차량의 임계속도 계산)

  • Kang, Juseok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.11
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    • pp.1371-1377
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    • 2013
  • In this analysis, a method is presented to calculate the critical speed of a railway vehicle by using a multibody dynamic model. The contact conditions and contact forces between the wheel and the rail are formularized for the wheelset model. This is combined with the bogie model to obtain a multibody dynamic model of a railway vehicle with constraint conditions. First-order linear dynamic equations with independent coordinates are derived from the constraint equations and dynamic equations of railway vehicles using the QR decomposition method. Critical speeds are calculated for the wheelset and bogie dynamic models through an eigenvalue analysis. The influences of the design parameters on the critical speed are presented.

Effect of Crosswind on Derailment of Railway Vehicles Running on Curved Track at Low Speed

  • Hosoi, Takahiro;Tanifuji, Katsuya
    • International Journal of Railway
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    • v.5 no.2
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    • pp.93-101
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    • 2012
  • Owing to the lightening of railway vehicles and increased operation speeds, the reduction of running safety in the presence of crosswind is becoming an important problem. In particular, the running safety tends to decrease when vehicles run on curved track. When a crosswind acts on a vehicle negotiating a curve from the outer side, flange climbing can occur. In this study, a full-vehicle model was constructed using the multi-body simulation software SIMPACK, and a simulation of a bogie vehicle with two-axle trucks negotiating a curve was carried out to examine the running safety under the condition where a crosswind acts on the vehicle from the outer side of the curve. As a result, it was verified that the derailment coefficient of the first wheelset becomes large in the exit transition curve and the coefficient of the third wheelset does in the entrance transition curve, and this trend becomes pronounced at low operation speeds in the presence of a stronger crosswind. It was also shown that the critical derailment coefficients obtained by modified Nadal's formula considering the effect of attack angle become close to the actual derailment coefficients at the timing that flange climbing occurs.

Wheel-Rail Contact Analysis Considering Axle Deformation Using a One-Dimensional Beam Element (1차원 빔요소를 활용한 차축 변형고려 차륜-레일 접촉해석)

  • Choi, Ha-Young;Lee, Dong-Hyung;Kwon, Seok-Jin;Seo, Jeong-Won
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.6
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    • pp.139-145
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    • 2017
  • It is necessary to analyze the exact contact position and contact stress of the wheel-rail in order to predict damage to the wheel and rail. This study presents a wheel-rail contact analysis model that considers the deformation of the axle. When a wheel-rail contact analysis is performed using a full three-dimensional model of the wheelset and rail, the analytical model becomes very inefficient due to the increase in analysis time and cost. Therefore, modeling the element-coupling model of the wheel and rail as a three-dimensional element and the axle as a one-dimensional element is proposed. The wheel-rail contact characteristics in the proposed analysis model for straight and curved lines were analyzed and compared with the conventional three-dimensional analysis model. Considering the accuracy of the analysis results and time, the result shows that the proposed analytical model has almost the same accuracy as a full three-dimensional model, but the computational effort is significantly reduced.

Utilization of wheel derailment test facilities (차륜탈선 시험설비의 활용방안)

  • Ham, Young-Sam;You, Won-Hee
    • Proceedings of the KSR Conference
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    • pp.1128-1133
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    • 2011
  • This is a testing equipment system to analyze variation of creep force according to wheel-rail tread profile, running speed of vehicle, vertical and lateral force, wheel/rail contact point, attack angle and so on. The creep force affect vehicle derailment, especially climbing derailment. This system is composed of main frame, wheelset and rail disks driver, hydraulic actuator, controller, environmental chamber, safety system and so on.

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Development of Train Load Model for Railway Bridge Time-History Analysis (철도교량의 동해석을 위한 하중모델의 개발)

  • 김현민;오지택
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.97-102
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    • 2003
  • A real train load fluctuates along the track because of complicated movements(Bouncing, Rolling, Pitching and Yawing) and rail conditions. This research has for its object in development of a numerical real train load model including fluctuation characteristics of lateral forces. It is based on Klingel movement theory of a wheelset on straight track it presents a propriety of application by comparison between a 3D-Numerical analysis result using this train load model and a measured data. And this paper presents further study subject to improve a method about the train load modeling.

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On the conceptual design of the gauge-adjustable wheelset for the north-east asia network (동북아 철도망 연계를 위한 궤간가변장치 개념설계)

  • Jang Seung-Ho;Na hui-Seung;Han Jun-Seok
    • Proceedings of the KSR Conference
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    • pp.281-284
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    • 2005
  • A gauge-adjustable system can be used for the fast and safe transportation in the railways with different gauges instead of transshipment or bogie-changing. The system will be necessary to connect the trans-Korean railway with the transcontinental railway effectively. In this paper, the technical requirements for the gauge-adjustable system used for the north-east asia network were studied and the conceptual design of the system was performed. For the purpose, the specification was made and the QFD and TRIZ methods are used.

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Study of Influence of Wheel Unloading on Derailment Coefficient of Rolling Stock (철도차량의 윤중 감소가 탈선계수에 미치는 영향 연구)

  • Koo, Jeong Seo;Oh, Hyun Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.2
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    • pp.177-185
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    • 2013
  • A new theoretical derailment coefficient model of wheel-climb derailment is proposed to consider the influence of wheel unloading. The derailment coefficient model is based on the theoretical derailment model of a wheelset that was developed to predict the derailment induced by train collisions. Presently, in domestic derailment regulations, a derailment coefficient of 0.8 is allowable using Nadal's formula, which is for a flange angle of $60^{\circ}$ and a friction coefficient of 0.3. However, theoretical studies focusing on different flange angles to justify the derailment coefficient of 0.8 have not been conducted. Therefore, this study theoretically explains a derailment coefficient of 0.8 using the proposed derailment coefficient model. Furthermore, wheel unloading of up to 50% is accepted without a clear basis. Accordingly, the correlation between a wheel unloading of 50% and a derailment coefficient of 0.8 is confirmed by using the proposed derailment coefficient model. Finally, the validity of the proposed derailment coefficient model is demonstrated through dynamic simulations.

A Study on Prediction Method of Derailment Behaviors due to Cross-wind Considering Dynamic Effects of Wheel-rail Interaction (차륜-레일의 동적효과를 고려한 측풍 원인 탈선 예측방법 연구)

  • Kim, Myung Su;Koo, Jeong Seo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.699-709
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    • 2014
  • This paper proposes a new method for predicting the derailment of a running train under cross-wind conditions, using the single wheelset derailment theory. The conventional theories used for predicting the derailment due to cross-winds were developed under the assumption that derailment will always be of the roll-over type, thus neglecting other possible types such as wheel-climbing, which may occur under special driving conditions. In addition, these theories do not consider running conditions such as dynamic wheel-rail interactions and friction effects. The new method considers the effects of dynamic wheel-rail interaction as well as those of lateral acceleration, rail cant, and cross-winds. The results of this method were compared and verified with those of the conventional methods and numerical simulations.

A development of the 2-point Whee-Rail Contact Algorithm (휠-레일 2점 접촉 해석 알고리즘 개발에 관한 연구)

  • Jeong, Gi-Beom;Park, Tae-Won;Park, Jae-Heung;Chung, Nam-Ho
    • Proceedings of the KSR Conference
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    • pp.1888-1893
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    • 2011
  • Considering the dynamic performance and stability of railroad vehicles has begun to grab the attention because of developing the high speed train recently. A development based on an analysis of dynamics and verification has to be required to study the stability of vehicle performance. Several ways of analysis were using the look-up table to apply the wheel-rail contact characteristics quickly, whereas there is a constraint of the wheelset lateral displacement. In this study, an development of searching the wheel-rail contact position has been provided. The 2-point contact between wheel and rail during the driving condition can be calculated by numerical analysis. Moreover, a reliability is verified by comparing the result with a commercial program.

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Analysis of Dynamic Characteristics of High Speed Trains Using a Time Varying Frequency Transform (시간-주파수 변환을 이용한 고속철도차량의 동특성 분석)

  • Lee, Jun-Seok;Choi, Sung-Hoon;Kim, Sang-Soo;Park, Choon-Soo
    • Proceedings of the KSR Conference
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    • pp.841-848
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    • 2008
  • This paper examined dynamic characteristics of high speed trains using a time varying frequency transform. Fourier transform based methods are frequently used for the calculation of the dynamic characteristics of trains in the frequency domain, but they cannot represent the time-varying characteristics. Therefore it is necessary to examine their characteristics using a time-varying frequency transform. For the examination, the non-stationary vibration of wheelset, bogie, and carbody are measured using accelerometers and stored in a data aquisition system. They are processed with localization of the data by modulating with a window function, and Fourier transform is taken to each localized data, called the short-time Fourier transform. From the processed results, time varying auto-spectral density, cross-spectral density, frequency response, and coherence functions have been calculated. From the analysis, it is confirmed that the time varying frequency transform is a useful method for analyzing the dynamic characteristics of high speed trains.

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