An Analysis of the Sound Transmission through a Plate Installed inside an Impedance Tube

Hyun-Sil Kim; Bong-Ki Kim; Sang-Ryul Kim; Seong-Hyun Lee

doi:10.7776/ASK.2015.34.3.219

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2015 Vol.34, Issue 3 Preview Page Next Page

An Analysis of the Sound Transmission through a Plate Installed inside an Impedance Tube 임피던스 튜브 내에 설치된 평판의 음파투과해석

31 May 2015. pp. 219-226

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Abstract

In this paper, derivation of the STL (Sound Transmission Loss) of a square plate installed in an impedance tube is discussed using an analytic method. Coupled motion of the plate vibration and acoustic field is considered. Vibration of the plate and pressure field inside the tube are expressed in terms of the infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results. When the boundary of the plate is clamped, vibration mode is assumed as a multiplication of the beam modes corresponding to the crosswise directions. The natural frequencies of the clamped plate are calculated using the Rayleigh-Ritz method. It is found that the STL shows a dip at the lowest natural frequency of the plate, and increases as the frequency decreases below the natural frequency. Comparison of the result in this paper with the STL obtained by measurements and FE computations in the reference shows an excellent agreement.

Keywords

Impedance tube

STL

natural frequency of a plate

본 논문은 단면이 정사각형인 임피던스 튜브 내에 고정된 평판의 STL(Sound Transmission Loss)을 해석적으로 구하는 방법을 다루었다. 평판의 진동과 튜브 내의 음장의 연성거동(coupled motion)을 고려하였는데 평판의 진동과 튜브 음장을 무한 급수의 합으로 전개하였으며 평면파 가정을 이용하여 처음 몇 개의 모드만 고려하여도 충분히 정확한 결과를 얻음을 보였다. 평판은 클램프(clamp) 지지로 가정하였는데 진동 모드는 단면의 가로 및 세로방향 보(beam) 진동 모드의 곱으로 전개하였고 고유진동수는 Rayleigh-Ritz 방법을 이용하여 구하였다. 평판의 STL은 가장 낮은 고유진동수에서 골(dip)을 가지며 주파수가 이보다 작아지면 STL은 커짐을 보였다. 기존 논문의 측정 및 FEM(Finite Element Method) 해석결과와 비교한 결과 잘 일치함을 확인하였다.

키워드

임피던스 튜브

음향투과손실(STL)

평판의 고유진동수

References

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9.L. Meirovitch, Analytical Methods in Vibrations, (The MacMillan Company, New York, 1967), Chapter 6-3.

10.R. D. Blevins, Formulas for Natural Frequency and Mode Shape, (Van Nostrand Reinhold Company, New York, 1979), pp. 261.

Information

Publisher :The Acoustical Society of Korea
Publisher(Ko) :한국음향학회
Journal Title :The Journal of the Acoustical Society of Korea
Journal Title(Ko) :한국음향학회지
Volume : 34
No :3
Pages :219-226
Received Date : 2015-01-13
Accepted Date : 2015-04-28
DOI :https://doi.org/10.7776/ASK.2015.34.3.219

The Journal of the Acoustical Society of KoreaISSN:1225-4428(Print) 2287-3775(Online)한국음향학회

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