Experiment and simulation analysis on noise reduction of cylindrical shells with viscoelastic material

For the issue concerning internal noise reduction of Al-made cylindrical shell structure, the noise control method of laying melamine foam (MF) layer is adopted for in-shell noise attenuation experiments of Al and Al/MF cylindrical shells and corresponding internal noise response spectrograms are obtained. Based on the Virtual.Lab acoustics software, a finite element model is established for the analysis of noise in the Al/MF cylinder shell and numerical simulation computation is conducted for the acoustic mode and in-shell acoustic response; the correctness of the finite element model is verified via comparison with measured data. On this basis, influence rules of different MF laying rate and different laying thickness on acoustic cavity resonance response within the low and medium frequency range of 100–400 Hz are studied. It is indicated that noise reduction increases with MF laying rate, but the amplification decreases along with the rising of MF laying rate; noise reduction per unit thickness decreases with the increase of laying thickness, while noise reduction per unit area increases.

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Noise Reduction of Elastic Structure Paste Viscoelastic Material Based on Complex Radius Vector of Virtual Source

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.164.227 ◽

2012 ◽

Vol 164 ◽

pp. 227-230

Author(s):

Yu Ming Wang ◽

Yuan An He ◽

De Jiang Shang

Keyword(s):

Noise Reduction ◽

Viscoelastic Material ◽

Cylindrical Shells ◽

Complex Structure ◽

Sound Field ◽

Radius Vector ◽

Superposition Method ◽

Virtual Source ◽

Radiated Sound ◽

Reduction Characteristics

It is hard to theoretically calculate the noise reduction characteristics for underwater complex structure of paste viscoelastic material. This paper introduces complex radius vector inside radiator based on the advantages of singular integral provided by traditional virtual source superposition method to calculate the radiated sound field from finite cylindrical shells. This method adapts truncation regularization filter to overcome the effect of background noise to enhance the calculation accuracy and then use impedance transmission theory to calculate the noise reduction characteristics of the cylindrical shells paste viscoelastic material. Numerical simulations show the calculation accuracy is greatly dependent on the size and position of the distributed virtual sources. There exists an optimal complex radius to minimize the error.

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Simulation Analysis of Cylindrical Shell Cavity Noise with Melamine Foam Lining

Shock and Vibration ◽

10.1155/2021/6646596 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Menghui Qi ◽

Bin Li ◽

Shilin Yan ◽

Qinghua Yan ◽

Qiyu He

Keyword(s):

Cylindrical Shell ◽

Noise Reduction ◽

Simulation Analysis ◽

Cylindrical Shells ◽

Element Model ◽

Measured Data ◽

Frequency Noise ◽

Precision Instrument ◽

Different Thickness ◽

Melamine Foam

To solve the problem of the harsh midlow frequency noise of rocket fairing, the cylindrical section of the protective precision instrument fairing is simplified as cylindrical shells, and different lining strategies of melamine foam (MF) are studied experimentally and numerically. Based on Virtual.Lab Acoustic software, a finite element model of the cylindrical cavity is established, and the correctness is verified by comparison with the measured data. On that basis, the influences of the lining position of different thickness MF on the noise reduction of cylindrical shells are investigated. It is shown that the thickness and location of the laying material have a significant effect on the noise reduction at the same specific gravity.

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