LOW-FREQUENCY ACOUSTIC TRANSMISSION OF HIGH-SPEED TRAINS: SIMPLIFIED VIBROACOUSTIC MODEL

Increase in speeds of modern railway trains is usually accompanied by higher levels of generated ground vibrations. In the author's earlier paper [V.V. Krylov, Applied Acoustics, 44, 149–164 (1995)], it has been shown that especially large increase in vibration level may occur if train speeds v exceed the velocity of Rayleigh surface waves in the ground cR., i.e., v > cR. Such a situation might arise, for example, with French TGV trains for which speeds over 515 km/h have been achieved. The present paper investigates the effect of geological layered structure of the ground on ground vibrations generated by high-speed trains. It is shown that, since Rayleigh wave velocities in layered ground are dispersive and normally increase at lower frequencies associated with deeper penetration of surface wave energy into the ground, the trans-Rayleigh condition v > cR may not hold at very low frequencies. This will cause a noticeable reduction in low-frequency components of generated ground vibration spectra. Theoretical results are illustrated by numerically calculated frequency spectra of ground vibrations generated by single axle loads travelling at different speeds and by TGV or Eurostar high-speed trains.

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Running Safety Assessment of Trains on Bridges under Earthquakes Based on Spectral Intensity Theory

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455421400083 ◽

2021 ◽

Author(s):

Wei Guo ◽

Yang Wang ◽

Hanyun Liu ◽

Yan Long ◽

Lizhong Jiang ◽

...

Keyword(s):

High Speed ◽

Safety Assessment ◽

Low Frequency ◽

Interaction Model ◽

Spectral Intensity ◽

Dynamic Responses ◽

Running Safety ◽

High Speed Trains ◽

Track Bridge ◽

Multi Body

The main goal of this paper is to perform the safety assessment of high-speed trains (HSTs) on the simply supported bridges (SSBs) under low-level earthquakes, which are frequently encountered by HSTs, utilizing spectral intensity (SI) index. First, the HST’s limit displacements, which are calculated by using the multi-body train model with detailed wheel–rail relationship, varying with train speed, frequency and amplitude of a sinusoidal base excitation are obtained. Then, based on the obtained HST’s limit displacements, the spectral intensity limits (SIL) graded by the train’s running speed are calculated, and the relationship between the bridge seismic dynamic responses and the train’s running safety was established. Next, the method that utilizes the SI and the SIL indexes to evaluate the HST’s running safety was proposed and verified by comparing with the evaluation result of the train–track–bridge interaction model. Based on the proposed SI index, the HST’s running safety on the SSBs was evaluated under earthquakes, considering different pier heights and site types. The results showed that the low-frequency components of the ground motions are unfavorable to the HST’s running safety, and the height of bridge piers has a significant impact on running safety.

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Improving the noise reduction performance of gangway bellows by using multilayered structures

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409720985628 ◽

2021 ◽

pp. 095440972098562

Author(s):

Hee-Min Noh

Keyword(s):

Noise Reduction ◽

Silicone Rubber ◽

High Speed ◽

Low Frequency ◽

Interior Noise ◽

Frequency Noise ◽

Multilayered Structures ◽

Interior Space ◽

High Speed Trains ◽

Verification Test

Excessive interior noise in railway vehicles is a major cause of fatigue and discomfort for passengers. In particular, the between-cars sections of high-speed trains experience considerable interior noise due to the poor noise reduction performance of the bellows, which are primarily made of silicone rubber and thus have a lower density than that of other components, made of extruded aluminum. Therefore, the objective of this study was to improve the noise reduction performance of such bellows. First, the material properties of silicone rubber were analyzed. Based on the results, the noise transmission of a simple model was analyzed to determine approaches required to reduce the low-frequency interior noise of the between-cars sections. It was confirmed that the low-frequency noise could be reduced by incorporating a multilayered panel of silicone rubber. Therefore, multilayered structures were considered for incorporation in the interior space of the between-cars sections of an actual high-speed train. A curved driving simulation of the between-cars sections indicated that no interference occurs when applying the proposed approach. Furthermore, a comparative test regarding the noise reduction performance was conducted considering cases involving bellows with and without multiple layers. The results of the verification test demonstrated that the noise reduction performance when using the proposed approach was improved by 4 dB compared with that in the case involving the conventional bellows, and an improvement of 8 dB or more was observed for noise with a low-frequency of 100 Hz.

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Numerical prediction of low-frequency ground vibrations induced by high-speed trains at Ledsgaard, Sweden

Soil Dynamics and Earthquake Engineering ◽

10.1016/s0267-7261(03)00061-7 ◽

2003 ◽

Vol 23 (6) ◽

pp. 425-433 ◽

Cited By ~ 47

Author(s):

R. Paolucci ◽

A. Maffeis ◽

L. Scandella ◽

M. Stupazzini ◽

M. Vanini

Keyword(s):

High Speed ◽

Low Frequency ◽

Numerical Prediction ◽

Ground Vibrations ◽

High Speed Trains

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Low Frequency Aerodynamic Noise from High Speed Trains

Quarterly Report of RTRI ◽

10.2219/rtriqr.59.2_109 ◽

2018 ◽

Vol 59 (2) ◽

pp. 109-114 ◽

Cited By ~ 2

Author(s):

Toki UDA ◽

Toshiki KITAGAWA ◽

Sanetoshi SAITO ◽

Yusuke WAKABAYASHI

Keyword(s):

High Speed ◽

Low Frequency ◽

Aerodynamic Noise ◽

High Speed Trains

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Low-frequency aerodynamic sound from high-speed trains

The Proceedings of the Symposium on Environmental Engineering ◽

10.1299/jsmeenv.2017.27.123 ◽

2017 ◽

Vol 2017.27 (0) ◽

pp. 123

Author(s):

Toki UDA ◽

Yoichi SAWAMURA ◽

Toshiki KITAGAWA ◽

Sanetoshi SAITOH ◽

Yusuke WAKABAYASHI

Keyword(s):

High Speed ◽

Low Frequency ◽

Aerodynamic Sound ◽

High Speed Trains

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Low-Frequency Carbody Sway Modelling Based on Low Wheel-Rail Contact Conicity Analysis

Shock and Vibration ◽

10.1155/2020/6671049 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Yi Wu ◽

Jing Zeng ◽

Sheng Qu ◽

Huailong Shi ◽

Qunsheng Wang ◽

...

Keyword(s):

High Speed ◽

Ride Comfort ◽

Low Frequency ◽

Fundamental Solutions ◽

Nonlinear Analyses ◽

Suspension Parameters ◽

Hunting Motion ◽

High Speed Trains ◽

Rail Line ◽

Economic Considerations

Low-frequency carbody swaying on China’s high-speed trains is not only an impediment to ride comfort but it may also be an operational risk under some extreme situations. To study the mechanism and mitigate the carbody swaying problem for high-speed trains, a multibody dynamics model was established based on both linear and nonlinear analyses. Whilst it is generally assumed that carbody swaying is predominantly caused by carbody hunting motion, the results in this paper has shown that, under certain boundary conditions, bogie-hunting motion can also lead to low-frequency carbody swaying. This low-frequency swaying phenomenon was also found to be caused by the excessively low wheel-rail contact or mismatched suspension parameters. Parametric optimization analysis was accordingly conducted from the perspective of the wheel-rail contact relationship and the suspension system. The analysis indicated that although optimizing the suspension parameters can meet the requirement of vehicle stability, bogie's vibration worsen when the wheel profiles wear over time. Overall, while rail reprofiling was found to be one of the fundamental solutions to mitigate carbody swaying, it is cost prohibitive for most routine operational applications. Thus, for economic considerations and the fact that low wheel-rail contact conicity is also a contributing factor to carbody swaying, vehicles with worn wheels can also be operated on the rail line, which was successfully verified by the field data presented in this paper.

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