Radiation modes and the active control of sound power

Elliott, Stephen J.; Johnson, Marty

doi:10.1121/1.407490

Cited by 309 publications

(206 citation statements)

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“…This approach also provides a model for the case of a perforated plate set in an infinite rigid baffle which has not been covered in Chapter 5. In principle, the concept is similar to the models of Vitiello et al [25], Cunefare and Koopman [26], Elliott and Johnson [27] and Gardonio et al [28] which used discrete elementary radiators to replace a continuous radiator. However, as will be shown later, the self-radiation impedance used in the proposed model is slightly different.…”

Section: Modelled By Discrete Sourcesmentioning

confidence: 83%

“…In the models of Elliott and Johnson [27] and Gardonio et al [28], the impedance of the elementary radiator is defined by…”

Section: Discrete Version Of Rayleigh Integralmentioning

confidence: 99%

“…Vitiello et al [25], Cunefare and Koopmann [26], Elliott and Johnson [27] and Gardonio et al [28] used an approach based on elementary radiators. The plate was divided into rectangular sources, where for each source, the normal time-harmonic velocity was defined at its centre position.…”

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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: Modelled By Discrete Sourcesmentioning

confidence: 83%

“…In the models of Elliott and Johnson [27] and Gardonio et al [28], the impedance of the elementary radiator is defined by…”

Section: Discrete Version Of Rayleigh Integralmentioning

confidence: 99%

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Sound radiation from perforated plates

Putra

Thompson

2010

Journal of Sound and Vibration

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“…The vector of the normal velocities of each element is denoted as ()  U . The acoustic power can be expressed as [4] …”

Section: Sound Power Analysis Of Laminated Platesmentioning

confidence: 99%

Double-Objective Optimization of Laminated Composite Plates for Natural Frequency Separation and Radiation Acoustic Power

Wang¹,

Wu²

2017

dtetr

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Abstract. In this study, frequency separation maximization and radiation acoustic power minimization of the laminated plate are simultaneously considered based on genetic algorithm. A double-objective genetic algorithm is used to obtain Pareto-optimal designs for frequency separation maximization and radiation acoustic power minimization. A four-layer laminated plate is used as an example, and the numerical simulations show that different weight coefficient ratios are chosen, Pareto optimal solution of double objective of the laminated plate are obtained.

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“…For this kind of problem, a relevant approach is to compute the radiating power or, equivalently, the radiation efficiency. For this task, the method of elementary radiators can be used [19]. This suggests to "discretize" the plate into elementary surfaces of same area S radiator and constant normal velocities, and to compute the radiation efficiency as…”

Section: Application To a Plate Radiating In An Acoustic Fluidmentioning

confidence: 99%

A model reduction strategy for computing the forced response of elastic waveguides using the wave finite element method

Mencik¹

2012

Computer Methods in Applied Mechanics and Engineering

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Radiation modes and the active control of sound power

Cited by 309 publications

References 10 publications

Sound radiation from perforated plates

Sound radiation from perforated plates

Double-Objective Optimization of Laminated Composite Plates for Natural Frequency Separation and Radiation Acoustic Power

A model reduction strategy for computing the forced response of elastic waveguides using the wave finite element method

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