• Title/Summary/Keyword: Structure borne noise

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Counter Plan for Reduction of Elevated Railway Bridge Noise (고가교 철도소음 저감을 위한 대책수립)

  • Kim, Byoung-Sam;Lee, Tae-Keun;Han, Sung-Ik;Yeo, Dae-Yeon;Kim, Hyung-Doo
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.6-12
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    • 2010
  • The source of wayside noise for the train are the aerodynamic noise, wheel/rail noise, and power unit noise. The major source of railway noise is the wheel/rail noise caused by the interaction between the wheels and rails. The Structure borne noise is mainly a low frequency problem. The train noise and vibration nearby the elevated railway make one specific issue. The microphone array method is used to search sound radiation characteristics of elevated structure to predict the noise propagation from an elevated railway. In this paper, the train noise and structure borne noise by train are measured. From the results, we investigated the effect on the sound absorption tunnel for elevated railway.

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POSSIBILITIES TO IMPROVE TRANSIENT GEAR SHIFT NOISE (SHIFT CLONK) IN A PASSENGER CAR

  • BIERMANN J. W.;REITZ A.
    • International Journal of Automotive Technology
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    • v.6 no.1
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    • pp.23-28
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    • 2005
  • The presented investigation of shift clonk in a vehicle with front-wheel drive shows how a detailed analysis of the complete acoustic system with respect to excitation, transfer and radiation foremost enables possibilities of noise reduction to be worked out. One of the most important basics for the shift clonk analysis was a synchronous measurement of both, torsional vibrations in the drive train on the excitation side as well as airborne and structure-borne noise signals on the transfer and radiation side. Thus, root causes could be identified and improvement measures of the internal shift system could be worked out. An analysis of the transfer paths by means of airborne and structure borne noise measurements made evident that the side shafts were responsible for the disturbing frequencies in the transfer paths. With the help of the FE-simulation it was possible to develop measures of structure optimisation for the side shaft system. The realisation of these measures clearly reduced the shift-noises in the vehicle interior.

Numerical Analysis of the Mechanical Impedance and Transmitted Vibration of the Foundation for the Equipment in a Naval Vessel (수치해석을 이용한 함정용 장비 받침대의 기계적 임피던스 및 전달 진동 분석)

  • Han, Hyung-Suk;Son, Yoon-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.5
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    • pp.462-467
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    • 2009
  • Reduction of the structure-borne noise of the naval vessel is very important in order to reduce the underwater radiated noise of it. One of the important factors to reduce the structure-borne noise of the installed machine in a ship is the design of the foundation having sufficiently high mechanical impedance. In this paper, the mechanical impedance of the foundation for the fan-coil unit in a naval vessel is evaluated numerically according to variation of the thickness of the foundation. And also, the forced vibration analysis is conducted considering the dynamic property of the anti-vibration mount. Through the analysis results, it can be known that the dynamic property of the anti-vibration mount should be considered when the minimum level of the mechanical impedance of the foundation is set.

A Suggestion of Method to reduce the Radiation Efficiency of Dash Panel of a Passenger Car (승용차 대시부의 구조 방사 효율 저감 방법 제안)

  • Kim, Young-Ki;Kang, Yeon-June;Ahn, Ok-Kyun;Ki, Ji-Hyeon;Park, Yoon-Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.332.1-332
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    • 2002
  • The study was performed as reduction method using finite and boundary element analysis on structure-borne noise radiated by dash panel of a real car. The radiation efficiency is used to estimate sound noise of dash panel. Curvature and edges of dash panel have effect on radiation efficiency. The simulation results of dash panel was ensured by comparison between experimental results and simulation results of a simple rectangular plate. (omitted)

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Calculation of Coupling Loss Factor for Small reverberation cabin using Statistical Energy Analysis (통계적 에너지 해석법을 이용한 소형 잔향실의 연성손실계수 측정)

  • 김관주;김운경;윤태중;김정태
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.797-801
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    • 2003
  • The Statistical Energy Analysis is based on the power flow and the energy conservation between sub-systems, which enable the prediction of acoustic and structural vibration behavior in mid-high frequency ranges. This paper discusses the identification of SEA coupling loss factor parameters from experimental measurements of small reverberation chamber sound pressure levels and structural accelerations. As structural subsystems, steel plates with and without damping treatment are considered. Calculated CLFs were verified by both transmission loss values for air-borne CLF case and running SEA commercial software As a result, CLFs have shown a good agreement with those computed by software. Acoustical behavior of air-borne noise and structure-borne noise has been examined. which shows reasonable results, too.

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