• International Journal of Railway
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• v.7 no.4
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• pp.109-116
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• 2014

For optimization of a low-noise track system, rail vibration and noise radiation needs to be investigated. The main influencing parameters for the noise radiation and the quantitative results of every track system can be obtained using a calculation model of generation and radiation of railway noise. This kind of model includes contact modeling and the calculation model of the dynamic properties of the wheel and the rail. This study used a nonlinear wheel/rail interaction model in the time domain to investigate the excitation of the rolling noise. Wheel/rail response is determined by time integrating Green's function of the rail together with force impulses from the wheel/rail contact. This model and the results of the study can be used for supporting calculation with the conventional model by an addition of the contributions due to nonlinearities to the roughness spectrum.

• Journal of KSNVE
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• v.10 no.3
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• pp.444-450
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• 2000

Wheel-rail noise is normally classified into three catagories : rolling impact and squeal noise. In this paper rolling noise caused by the irregularity between a wheel and a rail is analysed as follows: The irregularity between the wheel and the rail is assumed as linear superposition of sinusoidal profiles. Wheel-rail contact stiffness is linearized by using Hertzian contact theory and then contact force between the wheel and the rail is calculated. vibration of the rail and the wheel is calculated theoretically by receptance method or FEM depending on the geometry of the wheel or the rail for the frequency range of 100-500 Hz important for noise generation. The radiation noise caused by those vibration response is computed by BEM To verify this analysis tools rolling noise is calculated by proposed analysis steps using typical roughness data and these results are compared with experimental rolling noise data. This analysis tools show reasonable results and finally used for the prediction of the Korean high speed train rolling noise.

• Structural Engineering and Mechanics
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• v.48 no.4
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• pp.455-466
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• 2013

In recent years, many countries have added railway noise to the issues covered by noise regulations. It is known that the rail is the dominant source of rolling noise at frequency range of 500Hz-2000Hz for the conventional speeds (<160km/h). One of the effective ways to reduce noise from railway track is using a rail vibration absorber. To study the acoustic performance of rail absorber, the decay rates of vibration have long been used by researcher. In this paper, A FE model of a periodic supported rail with infinite element in ABAQUS is developed to study the acoustic performance of the rail absorber. To compute the decay rates, acceleration responses along the rail transferred to MATLAB to obtain response levels in frequency domain and then by processing the response levels, the decay rates obtained for each1/3octav band. Continous rail absorber is represented by a steel layer and an elastomer layer. The decay rates for conventional rail and rail with one-side absorber and also, the rail with two side absorber are obtained and compared. Then, to improve the system of rail absorber, a steel plate with elastomer layer is added to bottom of the rail foot. The vertical decay rate results show that the decay rate of rail vibration along the track is significantly increased around the tuned frequency of the absorber and thus the rail vibration energy is substantially reduced in the corresponding frequency region and also effective in rail noise reduction.

• Journal of KSNVE
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• v.10 no.3
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• pp.486-492
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• 2000

The major source of railway noises is rolling noise caused by the interaction of the wheels and rails. This rolling noise is generated by the roughness of the wheel /rail surface on tangent track in the absence of discontinuities such as wheel flats or rail joints. These roughness cause relative vibrations of the wheel and rail at their contact area. The vibrations generated at the contact area are treansmitted through the wheel and rail structures exciting resonances of the wheel and travelling waves in the rail. Then these vibrations radiate noise to the wayside. In this paper we predict the rollingnoise radiated from radial/axial motion of the wheel and vertical/lateral motion of the rail using Remington's analytical model and then compare of the predicted sound pressure and measured one. Although there are some inaccuracy in our prediction. these results show in good agreement between 500 Hz and 3150 Hz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.555-564
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• 2001

Wheel-rail noise is normally classified into three catagories ： rolling, squeal and impact noise. In this paper, rolling noise caused by the irregularity between a wheel and rail is analysed as follows： The irregularity between the wheel and rail is assumed as combination of sinusoidal profiles. Wheel-rail contact stiffness is linearized by using Hertzian contact theory, and then contact force between the wheel and rail is calculated. Vibration of the rail and wheel is calculated theoretically by receptance method or FEM depending on the geometry of wheel or rail for the frequency range of 100-5000Hz, important for noise generation. The radiation caused by those vibration is computed by BEM. To verify this analysis tools, rolling noise is calculated by preceding analysis steps using typical roughness data and it is compared with experimental rolling noise data. This analysis tools show reasonable results and used for the prediction of KTX rolling noise.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.161-164
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• 2010

The surface roughness of wheels and rails are known to be major contributory factors in wheel-rail rolling noise. Generally, the rail roughness was greater than the wheel roughness. Generally, rolling noise sizes and noise level in compliance with wheel/rail roughness almost are reported with the fact that is similar. Rolling noise important factors rightly being in compliance with roughness of contact point regions of the wheel/the rail, presented from the present paper.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.119-126
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• 2009

The noise emitted during train operation is generated with various reasons. It is known that the major noise generation is classified according to the ranges of train speed; that is, engine noise at lower speed range, rolling noise at medium speed range, and air-borne noise at higher speed range. These noises are transmitted in combined form with the noises generated from track components and under-carriage, etc. The rolling noise as a major noise at medium speed range is caused by the vibration occurred at wheel/rail interface. The vibration occurred at wheel/rail interface is transmitted to wheel and rail, and this vibration is emitted from wheel and rail as a noise. In this paper, a soundproof box which can simply measure the noise emitted from rail and analyze the characteristics of the measured noise is studied.

• Smart Structures and Systems
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• v.18 no.5
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• pp.1063-1085
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• 2016

Taking advantage of the high sensitivity and long-distance detection capability of acoustic emission (AE) technique, this paper focuses on the crack detection in rail head, which is one of the most vulnerable parts of rail track. The AE source location and noise cancellation were studied on the basis of practical rail profile, material and operational noise. In order to simulate the actual AE events of rail head cracks, field tests were carried out to acquire the AE waves induced by pencil lead break (PLB) and operational noise of the railway system. Wavelet transform (WT) was first utilized to investigate the time-frequency characteristics and dispersion phenomena of AE waves. Here, the optimal mother wavelet was selected by minimizing the Shannon entropy of wavelet coefficients. Regarding the obvious dispersion of AE waves propagating along the rail head and the high operational noise, the wavelet transform-based modal analysis location (WTMAL) method was then proposed to locate the AE sources (i.e. simulated cracks) respectively for the PLB-induced AE signals with and without operational noise. For those AE signals inundated with operational noise, the Hilbert transform (HT)-based noise cancellation method was employed to improve the signal-to-noise ratio (SNR). Finally, the experimental results demonstrated that the proposed crack detection strategy could locate PLB-simulated AE sources effectively in the rail head even at high operational noise level, highlighting its potential for field application.

• 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.

• Journal of the Korean Society for Railway
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• v.4 no.1
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• pp.31-37
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• 2001

There are three examples of noise reduction test by joint improvement. One of them is tested for electric car at joint rail and another is tested at expansion joint and long welded rail and the third is tested at open deck bridge. We can know from the result that the noise reduction effect of rail welding is very different to the type of track and the car. The condition of the test has some differences, but it may be useful reference of noise reduction