• Title, Summary, Keyword: Vehicle-track interaction

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A Moving Track Test Using Tire-Wheel Tracking Machine (고무바퀴트랙하중 시험기를 이용한 왕복하중실험)

  • Sung, Ik-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.1
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    • pp.250-256
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    • 2010
  • In this paper, an analytical and experimental study is performed in order to determine the effects of interaction between vehicle and bridge superstructure. For this purpose an improved wheel tracking machine and an adequate single span bridge are designed. Results presented in the paper show that wheel tracking machine including moving mass effects can demonstrate more accurate dynamic interaction between vehicle and structure.

Evaluation of Residual Stress for Thermal Damage of Railway Wheel Tread (차륜 답면의 열손상에 대한 잔류응력 평가)

  • Kwon, Seok-Jin;Seo, Jung-Won;Lee, Dong-Hyung;Ham, Young-Sam
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.5
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    • pp.537-542
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    • 2011
  • The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.

Prediction of Wear Rate for Rubber Track by Using Frictional Energy Analysis (마찰 에너지 해석을 통한 러버 트랙(Rubber Track)의 마모율 예측)

  • Kang, Jong-Jin;Cho, Jin-Rae;Jeong, Weui-Bong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.5
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    • pp.125-133
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    • 2011
  • The wear of rubber track being in contact with the road surface is an important subject because it decreases the traction performance and the operating efficiency of tracked vehicle. For the above reasons, many attempts have been made to quantitatively calculate the rubber track. However, it depends on the experimental methods which are highly time- and cost-consuming. Therefore, the numerical simulation approach is highly desirable, but it needs to model the complex geometry and the material behavior in details as well as the interaction with the road surface. In this study, the rubber track and its material behavior are elaborately modeled since these factors are very important in the prediction of the wear rate of the rubber track. Accordingly to the studies on the rubber wear by previous investigations, it has been found that the wear is greatly influenced by the frictional energy. The frictional energy of rubber track is computed by utilizing the 3D finite element analysis of the rubber track, and the wear rate is evaluated making use of the frictional energy and a wear model.

A Study on the dynamic behavior of rail due to dipped joints (레일이음매의 동적거동에 대한 연구)

  • Kang, Yun-Suk;Yang, Shin-Chu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.328-333
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    • 2002
  • When vehicle travelling along the track which has irregularity such as vertical profile, dynamic forces arise at the Wheel/Rail contact patch by wheel/rail interaction. In particular short wavelength irregularities on dipped joint and small stiffness of connecting rail bring about intense wheel/rail dynamic effects at higher speed. In the paper, a new model for dipped joint rail is developed to study dynamic behavior of track. A cusp behavior on dipped joint was defined by its amplitude and decay factor, which was presented by FRA track classes. The result of case study are presented, which show wheel rail contact force in each track classes, train operation speed and bending flexible rigidity ratio of fishplates which are connecting the rail.

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The Evaluation of Axial Stress in Continuous Welded Rails via Three-Dimensional Bridge-Track Interaction

  • Manovachirasan, Anaphat;Suthasupradit, Songsak;Choi, Jun-Hyeok;Kim, Bum-Joon;Kim, Ki-Du
    • 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.

Vibration Analysis of Station under Railway Lines with Floating Slab Track (플로팅 슬래브궤도를 적용한 선하역사 구조물 진동해석)

  • Jang, Seung-Yup;Cho, Ho-Hyun;Yang, Sin-Chu
    • Proceedings of the KSR Conference
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    • pp.1719-1724
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    • 2010
  • In the areas susceptible to vibration and noise induced by railway traffic such as downtown area and stations under railway lines, the vibration and the structure-borne noise can be solved by floating slab track system separating the entire track structure from its sub-structure using anti-vibration mat or springs. In other countries, the core technologies for vibration-proof design and vibration isolator - one of key components - have been developed and many installation experiences have been accumulated. However, in Korea, since the design technology of system and components are not yet developed, the foreign systems are being introduced without any adjustment. Thus, in this study, the vibration isolator has been developed and its performance are investigated by the dynamic analysis of a station structure under railways lines and the floating slab track system. For this purpose, the loads transferred from the vibration isolator of the floating slab track were evaluated by train running simulation considering vehicle-track interaction, and then the dynamic analysis of station structure subjected to these loads was performed. The dynamic analysis results show that the proposed floating slab track can reduce the vibration of structure by about 25dB compared with that in conventional ballast track without floating system.

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An Experimental Evaluation for an Abnormal Vibration on Running of the High Speed Train (고속열차 주행중 이상진동에 대한 시험적 평가)

  • Yang, Hee-Joo;Woo, Kwan-Je;Son, Byoung-Gu;Seong, Jae-Ho
    • Proceedings of the KSR Conference
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    • pp.2263-2268
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    • 2011
  • THE VIBRATION MODE OF RAILWAY VEHICLE IS DIFFICULT TO FIND OUT THE CHARACTERISTICS OF MOTION DURING THE OPERATION ON THE TRACK BECAUSE THESE HAPPEN TO INDEPENDENCE OR DUPLICATION MOTION CAUSED BY VEHICLE, WHEEL/RAIL INTERACTION, TRACK IRREGULARITY AND FAILURE OF THE SUSPENSION & POWER TRANSMISSION DEVICE ETC. IT IS NAMED AN ABNORMAL VIBRATION THAT THE VIBRATION, WHICH WAS PASSED THE PRIMARY AND SECONDARY SUSPENSION, IS AFFECTED TO THE PASSENGER OR DRIVER WITHOUT DAMPING. THIS PAPER DESCRIBES AN EXPERIENCE EVALUATION TO FIND OUT THE CAUSE OF AN ABNORMAL VIBRATION WHICH WAS HAPPEN AT THE CAB OF POWER CAR IN KTX-SANCHEON TRAINSET WHEN ON RUNNING AT HIGH SPEED ZONE.

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Manufacturing and Dynamic Performance test for Prototype Bogie of half Maglev vehicle (자기부상열차 시험용 1/2차량 대차제작과 주행성능 실험)

  • Lee, Nam-Jin;Han, Hung-Suk;Lee, Wan-Sang;Kim, Chul-Geun
    • Proceedings of the KSR Conference
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    • pp.1575-1580
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    • 2009
  • Maglev vehicle has two kinds of suspension system such as a secondary suspension with air-spring and a primary suspension as electromagnetic suspension which composed of electromagnet, magnet driver, controller and sensors. The interaction between each dynamic component of vehicle and track effects the stability and running performance. To achieve the specified performance of vehicle, many various approaches of research were tried, then as the result of these efforts, the first commercial operating with Maglev will start soon. The bogie for revenue service from 2012 has some significant modifications compared to the previous one, and to verify the changes the half prototype vehicle was manufactured and took the running performance test. In this report, we will introduce the stage of manufacturing and report results of dynamic performance tests to verify new concept of bogie mechanism.

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Fundamental Study on the Effect of Grousers on the Soil Thrust of Off-road Tracked Vehicles (그라우저 효과를 고려한 야지궤도차량의 지반추력 평가연구)

  • Baek, Sung-Ha;Chung, Choong-Ki
    • Journal of the Korean Geotechnical Society
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    • v.34 no.9
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    • pp.33-42
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    • 2018
  • When an off-road tracked vehicle travels, an engine thrust that is transmitted to the continuous track induces a shearing action on the soil-track interface. Consequently, the relative displacement known as slip displacement takes place on the soil-track interface, which develops an associated soil thrust acting as a traction force. For the loose or soft ground conditions, an excessively large slip displacement can be required for the development of the desired soil thrust which will make the tracked vehicle mobile and therefore the outer surface of the continuous track is generally designed to protrude with grousers. This paper fundamentally studied the effect of grousers on the soil thrust of off-road tracked vehicles. Based on the soil-track interaction theory, a new soil thrust assessment method that properly takes into account the effect of grousers was developed. Also, the soil thrust of off-road tracked vehicles equipped with a number of grousers was evaluated using the developed assessment method. The results showed that grousers increased the soil thrust of the continuous track, enhancing the overall tractive performance of off-road tracked vehicles. These effects were more obvious as the height of grouser increased and the spacing of grouser decreased; thus, it is concluded that the grouser which has smaller shape ratio (span of the grouser to a grouser height) significantly enhances off-road tracked vehicle's performance.

Assessment of Train Running Safety, Ride Comfort and Track Serviceability at Transition between Floating Slab Track and Conventional Concrete Track (플로팅 슬래브궤도와 일반 콘크리트궤도 접속구간에서의 열차 주행 안전, 승차감 및 궤도 사용성 평가)

  • Jang, Seung-Yup;Yang, Sin-Chu
    • Journal of the Korean Society for Railway
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    • v.15 no.1
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    • pp.48-61
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    • 2012
  • It is of great importance to assure the running safety, ride comfort and serviceability in designing the floating slab track for mitigation of train-induced vibration. In this paper, for this, analyzed are the system requirements for the running safety, ride comfort and serviceability, and then, the behavior of train and track at the floating slab track including the transition zone to the conventional concrete slab track according to several main design variables such as system natural frequency, arrangement of spring at transition, spacing of spring isolators, damping ratio and train speed, using the dynamic analysis technique considering the train-track interaction. The results of this study demonstrate that the discontinuity of the support stiffness at the transition results in a drastic increase of the dynamic response such as wheel-rail interaction force, rail bending stress and rail uplift force. Hence, it is efficient to decrease the spacing of springs or to increase the spring constants at the transition to obtain the running safety and serviceability. On the other hand, the vehicle body acceleration as a measure of ride comfort is little affected by the discontinuity of the stiffness at the transition, but by the system tuning frequency; thus, to obtain the ride comfort, it is of great significance to select the appropriate system tuning frequency. In addition, the effects of damping ratio, spacing of springs and train speed on the dynamic behavior of the system have been discussed.