On the noise transmission and control for a cylindrical chamber core composite structure

The increasing motivation behind the recently wide industrial applications of sandwich and composite double panel structures stems from their ability to absorb sounds more effectively. Meticulous selection of the geometrical and material constituents of both the core and panels of these structures can produce highly desirable properties. A good understanding of their vibro-acoustic response and emission index such as the sound transmission loss (STL) is, therefore, a requisite to producing optimal design. In this study, an overview of recent advances in STL of sandwich and composites double panels is presented. At first, some salient explanation of the various frequency and controlled regions are given. It then critically examines a number of parameter effects on the STL of sandwich and composite structures. Literatures on the numerical, analytical and experimental solutions of STL are systematically presented. Efficient and more reliable optimization problems that maximize the STL and minimize the objective functions capable of degrading the effectiveness of the structure to absorb sounds are also provided.

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“…Dip frequency where the circumferential wave number and mode per radius of shell become equal. [34,35] Coincidence…”

Section: Symbol Formula Definition Referencementioning

confidence: 99%

Comparative Study of Sound Transmission Losses of Sandwich Composite Double Panel Walls

2020

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“…In order to simplify analysis, the acoustic damping ratio was set to the same value for all modes and obtained by averaging the measured results (0.28%). 1,12 The structural damping ratio was also set to the same for all modes and obtained by averaging the identification results (4.64%). 1,12 The maximum order of acoustic and structural modes is set to six per each index in the simulation for a total of 36 structural modes and 216 acoustic cavity modes.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…Actually, both structural and acoustic axial modes of a finite cylindrical structure are experimentally found to be very important modes for noise control in low frequencies. 1,4,12 Gardonio, Ferguson and Fahy presented an expression of NR to characterize unit amplitude external incident sound transmission through a finite cylindrical shell. 13 From the equation of definition it is seen that the NR is defined based on the one proposed by Koval. However, the definition has some differences with Koval's NR.…”

Section: Introductionmentioning

confidence: 99%

Mathematical model for characterizing noise transmission into finite cylindrical structures

Vipperman

2005

The Journal of the Acoustical Society of America

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This work presents a theoretical study of the sound transmission into a finite cylinder under coupled structural and acoustic vibration. Particular attention of this study is focused on evaluating a dimensionless quantity, "noise reduction," for characterizing noise transmission into a small cylindrical enclosure. An analytical expression of the exterior sound pressure resulting from an oblique plane wave impinging upon the cylindrical shell is first presented, which is approximated from the exterior sound pressure for an infinite cylindrical structure. Next, the analytical solution of the interior sound pressure is computed using modal-interaction theory for the coupled structural acoustic system. These results are then used to derive the analytical formula for the noise reduction. Finally, the model is used to predict and characterize the sound transmission into a ChamberCore cylindrical structure, and the results are compared with experimental data. The effects of incidence angle and internal acoustic damping on the sound transmission into the cylinder are also parametrically studied.

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“…When properly designed, a passive method using an acoustic resonator can effectively absorb acoustic energy from a targeted acoustic mode. [1][2][3][4][5][6][7][8][9] Ideally, it is desirable to integrate resonators into the host structure to save space, particularly for small enclosures. However, it is difficult to meet this requirement with a classical Helmholtz resonator because of its bulbous profile.…”

Section: Introductionmentioning

confidence: 99%

Noise control in enclosures: Modeling and experiments with T-shaped acoustic resonators

et al. 2007

The Journal of the Acoustical Society of America

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This paper presents a theoretical and experimental study of noise control in enclosures using a T-shaped acoustic resonator array. A general model with multiple resonators is developed to predict the acoustic performance of small resonators placed in an acoustic enclosure. Analytical solutions for the sound pressure inside the enclosure and the volume velocity source strength out of the resonator aperture are derived when a single resonator is installed, which provides insight into the physics of acoustic interaction between the enclosure and the resonator. Based on the understanding of the coupling between the individual resonators and enclosure modes, both targeted and nontargeted, a sequential design methodology is proposed for noise control in the enclosure using an array of acoustic resonators. Design examples are given to illustrate the control performance at a specific or at several resonance peaks within a frequency band of interest. Experiments are conducted to systematically validate the theory and the design method. The agreement between the theoretical and experimental results shows that, with the help of the presented theory and design methodology, either single or multiple resonance peaks of the enclosure can be successfully controlled using an optimally located acoustic resonator array.

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On the noise transmission and control for a cylindrical chamber core composite structure

Cited by 11 publications

References 12 publications

Comparative Study of Sound Transmission Losses of Sandwich Composite Double Panel Walls

Comparative Study of Sound Transmission Losses of Sandwich Composite Double Panel Walls

Mathematical model for characterizing noise transmission into finite cylindrical structures

Noise control in enclosures: Modeling and experiments with T-shaped acoustic resonators

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