Sound radiation by a simply supported unbaffled plate

Laulagnet, Bernard

doi:10.1121/1.422765

Cited by 50 publications

(38 citation statements)

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“…For the latter, an approximate formula is developed. The sound radiation from a perforated unbaffled plate is then modelled by extending Laulagnet's model [33]. The result is compared with the model of a perforated plate in an infinite perforated baffle.…”

Section: Thesis Outlinementioning

confidence: 99%

“…Laulagnet [33] gave an alternative solution by also using the Kirchhoff-Helmholtz equation to represent the acoustic pressure. The surface integral for the Green's function was solved analytically by implementing a two-dimensional spatial Fourier transform.…”

Section: Unbaffled Plate Modelsmentioning

confidence: 99%

“…From the existing methods, particularly in [29] and [33], the results presented were only focused on single modes. The radiation efficiency due to vibration in multiple modes was calculated in [30,33,34] but only up to relatively low frequency. However, this is not still adequate to give a thorough analysis, particularly to provide a complete investigation into the difference between the radiation from the baffled and unbaffled plate.…”

Section: Unbaffled Plate Modelsmentioning

confidence: 99%

“…The plate mode shape function was defined by applying a set of trigonometric functions for arbitrary boundary conditions [35]. As in Laulagnet's model [33], the pressure jump was also expanded in terms of a series of modes. The radiation efficiency was obtained by first determining sets of matrices, namely radiation impedance, mass and stiffness matrices.…”

Section: Unbaffled Plate Modelsmentioning

confidence: 99%

“…Similar to the baffled plate in Chapter 2, the accuracy and computational efficiency of the existing models are discussed. Methods from Williams [23] and Laulagnet [33] are implemented to calculate the radiation efficiency of an unbaffled plate. The results are plotted and also compared with those of the baffled plate.…”

Section: Thesis Outlinementioning

confidence: 99%

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Sound radiation from perforated plates

Putra

Thompson

2010

Journal of Sound and Vibration

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FACULTY OF ENGINEERING, SCIENCE AND MATHEMATICS INSTITUTE OF SOUND AND VIBRATION RESEARCH Doctor of Philosophy SOUND RADIATION FROM PERFORATED PLATES by Azma PutraPerforated plates are quite often used as a means of engineering noise control to reduce the sound radiated by structures. However, there appears to be a lack of representative models to determine the sound radiation from a perforated plate. The aim of this thesis is to develop such a model that can be used to give quantitative guidance corresponding to the design and effectiveness of this noise control measure.Following an assessment of various models for the radiation efficiency of an unbaffled plate, Laulagnet's model is implemented. Results are calculated and compared with those for baffled plates. From this, simple empirical formulae are developed and give a very good agreement with the analytical result. Laulagnet's model is then modified to include the effect of perforation in terms of a continuously distributed surface impedance to represent the holes. This produces a model for the sound radiation from a perforated unbaffled plate. It is found that the radiation efficiency reduces as the perforation ratio increases or as the hole size reduces. An approximate formula for the effect of perforation is proposed which shows a good agreement with the analytical calculation up to half the critical frequency. This could be used for an engineering application to predict the noise reduction due to perforation.The calculation for guided-guided boundary conditions shows that the radiation efficiency of an unbaffled plate is not sensitive to the edge conditions. It is also shown that perforation changes the plate bending stiffness and mass and hence increases the plate vibration.The situation is also considered in which a perforated unbaffled plate is located close to a reflecting rigid surface. This is established by modifying the Green's function in the perforated unbaffled model to include an imaginary source to represent the reflected sound. The result shows that the presence of the rigid surface reduces the radiation efficiency at low frequencies.The limitation of the assumption of a continuous acoustic impedance is investigated using a model of discrete sources. The perforated plate is discretised into elementary sources representing the plate and also the holes. It is found that the uniform surface impedance is only valid if the hole distance is less than an acoustic wavelength for a vibrating rectangular piston and less than half an acoustic wavelength for a rectangular plate in bending vibration. Otherwise, the array of holes is no longer effective to reduce the sound radiation.Experimental validation is conducted using a reciprocity technique. A good agreement is achieved between the measured results and the theoretical calculation for both the unbaffled perforated plate and the perforated plate near a rigid surface.

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Section: Thesis Outlinementioning

confidence: 99%

Section: Unbaffled Plate Modelsmentioning

confidence: 99%

Section: Unbaffled Plate Modelsmentioning

confidence: 99%

Section: Unbaffled Plate Modelsmentioning

confidence: 99%

Section: Thesis Outlinementioning

confidence: 99%

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Sound radiation from perforated plates

Putra

Thompson

2010

Journal of Sound and Vibration

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Determination of the Mutual Radiation Resistances of a Rectangular Plate and Their Impact on the Radiated Sound Power

Gibeling

2000

Journal of Sound and Vibration

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Transmission of Sound Through Finite Multiple-Panel Partition

Xin

2014

Springer Tracts in Mechanical Engineering

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This chapter is organized as three parts: in the first part, the vibroacoustic performance of a rectangular double-panel partition with enclosed air cavity and simply mounted on an infinite acoustic rigid baffle is investigated analytically. The sound velocity potential method rather than the commonly used cavity modal function method is employed, which possesses good expandability and has significant implications for further vibroacoustic investigations. The simply supported boundary condition is accounted for by using the method of modal function, and double Fourier series solutions are obtained to characterize the vibroacoustic behaviors of the structure. Results for sound transmission loss (STL), panel vibration level, and sound pressure level are presented to explore the physical mechanisms of sound energy penetration across the finite double-panel partition. Specifically, focus is placed upon the influence of several key system parameters on sound transmission, including the thickness of air cavity, structural dimensions, and the elevation angle and azimuth angle of the incidence sound. Further extensions of the sound velocity potential method to typical framed double-panel structures are also proposed.In the second part, the air-borne sound insulation performance of a rectangular double-panel partition clamp mounted on an infinite acoustic rigid baffle is investigated both analytically and experimentally, and compared with that of a simply supported one. With the clamped (or simply supported) boundary accounted for by using the method of modal function, a double series solution for the sound transmission loss (STL) of the structure is obtained by employing the weighted residual (Galerkin) method. Experimental measurements with Al double-panel partitions having air cavity are subsequently carried out to validate the theoretical model for both types of the boundary condition, and good overall agreement is achieved. A consistency check of the two different models (based separately on clamped modal function and simply supported modal function) is performed by

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Sound radiation by a simply supported unbaffled plate

Cited by 50 publications

References 10 publications

Sound radiation from perforated plates

Sound radiation from perforated plates

Determination of the Mutual Radiation Resistances of a Rectangular Plate and Their Impact on the Radiated Sound Power

Transmission of Sound Through Finite Multiple-Panel Partition

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