• Title, Summary, Keyword: Rail acoustic roughness

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Measuring Technique For Acoustic Roughness of Rail Surface With Homogeneous Displacement Sensors (동일 변위센서를 사용한 레일표면 음향조도의 측정방법)

  • Jeong, Wootae;Jang, Seungho;Kho, Hyo-In
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.11
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    • pp.7941-7948
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    • 2015
  • Rolling noises during train operation are caused by vibration excited from irregularities of surface roughness between wheel and rail. Therefore, a proper measurement and analysis techniques of acoustic roughness between wheel and rail surface are required for transmission, prediction, and analysis of the train rolling noise. However, since current measuring devices and methods use trolley-based manual handling devices, the measurements induce unstable measuring speed and vibrational interface that increases errors and disturbances. In this paper, a new automatic rail surface exploring platform with a speed controller has been developed for improving measurement accuracy and reducing inconsistency of measurements. In addition, we propose a data integration method of the rail surface roughness with multiple homogeneous displacement sensors and verified the accuracy of the integrated data through standard test-bed railway track investigation.

Effect of Design variables of Rail Surface Measuring Device on Acoustic Roughness and Spectral Analysis (레일표면 측정장치의 설계변수가 음향조도 스펙트럼 분석에 미치는 영향)

  • Jeong, Wootae;Jeon, Seungwoo;Jeong, Dahae;Choi, Han Shin
    • Journal of the Korean Society for Railway
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    • v.20 no.4
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    • pp.440-447
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    • 2017
  • Spectrum level for the acoustic roughness of wheels and rail surface should be periodically maintained under the limitation of ISO to reduce rolling noise of railway vehicles. Thus, in maintaining railway track, displacement sensor-based measuring devices are broadly used to measure the surface roughness and to perform spectral analysis. However, these measuring devices cause unexpected measuring errors since the displacement sensors are fixed at moving platforms and the main frame produces pitching motion during measurement. To increase the accuracy of the measured values, this paper has investigated the effects of design variables such as wheel base, additional wheels, and elastic deformation of wheels on the surface roughness and acoustic roughness spectrum.

Study on the Rolling Noise Model Using an Analysis of Wheel and Rail Vibration Characteristics (철도 차륜 및 레일 진동 특성 해석을 통한 전동 소음 모델 연구)

  • Jang, Seungho;Ryue, Jungsoo
    • Journal of the Korean Society for Railway
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    • v.16 no.3
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    • pp.175-182
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    • 2013
  • Rolling noise is an important source of noise from railways; it is caused by wheel and rail vibrations induced by acoustic roughness at the wheel/rail contact. To reduce rolling noise, it is necessary to have a reliable prediction model that can be used to investigate the effects of various parameters related to the rolling noise. This paper deals with modeling rolling noise from wheel and rail vibrations. In this study, the track is modeled as a discretely supported beam by regarding concrete slab tracks, and the wheel vibration is simulated by using the finite element method. The vertical and lateral wheel/rail contact forces are modeled using the linearized Hertzian contact theory, and then the vibration responses of the wheel and rail are calculated to predict the radiated noise. To validate the proposed model, a field measurement was carried out for a test vehicle. It was found that the predicted result agrees well with the measured one, showing similar behavior in the frequency range between 200 and 4000 Hz where the rolling noise is prominent.

Characteristics of Vibration and Sound Radiated from Rails of Concrete Slab Tracks for Domestic High Speed Trains (국내 고속 철도 콘크리트 슬라브 궤도의 진동 및 방사 소음 해석)

  • Ryue, Jungsoo;Jang, Seungho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.7
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    • pp.605-616
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    • 2013
  • An important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. In the present paper, characteristics of rail vibration and radiated sound power from concrete slab tracks for domestic high speed train(KTX) is investigated by means of a numerical method. The waveguide finite element and boundary element are combined and applied for this analysis. The concrete slab track is modelled simply with a rail and rail pad regarding the concrete slab as a rigid ground. The wave types which contribute significantly to the rail vibration and radiated noise are identified in terms of the mobility and decay rates. In addition, the effect of the rail pad stiffness on the radiated power is examined for two different rail pad stiffnesses.

Comparison of track vibration characteristics for domestic railway tracks in the aspect of rolling noise (철도 전동 소음의 관점에서 해석한 국내 철도의 진동 특성 비교)

  • Ryue, Jungsoo;Jang, Seungho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.644-647
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    • 2013
  • The important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. The main contributors for rolling noise are the sleepers, rail and wheels. In order to analyze and predict rolling noise, it is necessary to understand the vibrating behaviors of railway tracks, as well as the wheels. In the present paper, theoretical modelings of the railway track are reviewed in terms of the rolling noise, and they are applied for the three representative types of domestic railway tracks operated: the conventional ballasted track, KTX ballasted track and KTX concrete track. The characteristics of waves propagating along rails were investigated and compared between the tracks. The tracks were modeled as discretely supported Timoshenko beams and compared in terms of the averaged squared amplitude of velocity which is directly related to the sound radiation from the rails.

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Numerical Analysis of Rail Noise Regarding Surface Impedance of Ground by Using Wavenumber Domain Finite and Boundary Elements (지면 임피던스를 고려한 레일 방사 소음의 파수영역 유한요소/경계요소 해석)

  • Ryue, Jungsoo;Jang, Seungho
    • Journal of the Korean Society for Railway
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    • v.18 no.4
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    • pp.289-300
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    • 2015
  • An important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. In conventional approaches to predicting rail noise, the rail is regarded as placed in a free space so that the reflection from the ground is not included. However, in order to predict rail noise close to the rail, the effect of the ground should be contained in the analysis. In this study the rail noise reflected from the ground is investigated using the wavenumber domain finite element and boundary element methods. First, two rail models, one using rail attached to the rigid ground and one using rail located above rigid ground, are considered and examined to determine the rigid ground effect in terms of the radiation efficiency. From this analysis, it was found that the two models give considerably different results, so that the distance between the rail and the ground is an important factor. Second, an impedance condition was set for the ground and the effect of the ground impedance on the rail noise was evaluated for the two rail models.

Comparison of Track Vibration Characteristics for Domestic Railway Tracks in the Aspect of Rolling Noise (철도 전동 소음의 관점에서 해석한 국내 철도의 진동 특성 비교)

  • Ryue, Jungsoo;Jang, Seungho
    • Journal of the Korean Society for Railway
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    • v.16 no.2
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    • pp.85-92
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    • 2013
  • An important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. The main contributors to rolling noise are the sleepers, rail, and wheels. In order to analyze and predict rolling noise, it is necessary to understand the vibrating behaviors of railway tracks, as well as of the wheels. In the present paper, theoretical modeling methods for railway track are reviewed in terms of rolling noise; these methods are applied for the three representative types of domestic railway tracks operated: the conventional ballasted track, KTX ballasted track and KTX concrete track. The characteristics of waves propagating along rails are investigated and compared among the types of tracks. The tracks are modeled as discretely supported Timoshenko beams and are compared in terms of the averaged squared amplitude of velocity, which is directly related to the sound radiation from the rails.

Identification and Reduction Method for Refrigerator Contraction and Expansion Noise (냉장고 수축팽창 소음원의 규명과 저감 방법)

  • Kim, Wonjin;Park, Seong Kyu
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.22 no.4
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    • pp.723-729
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    • 2013
  • The contraction and expansion noise of a refrigerator are investigated, and some effective methods are proposed to reduce the level and occurrence frequency of noise. First, the noise of a refrigerator is measured to estimate the frequency spectrum and occurrence frequency of noise. Second, a sound visualization was conducted using an acoustic camera to determine the location of the noise source. From the results, it was observed that the internal part mainly producing noise was the third shelf in the freezer room. A method to estimate the acceleration on the location of the noise source is introduced to analyze the contraction and expansion noise precisely and accommodate experimental convenience. Noise reduction methods such as the replacement of the existing shelf with glass shelves, adoption of rail slides, and increase of roughness on the contact surface of the shelf are proposed and tested.