Sound radiation from rectangular baffled and unbaffled plates

Putra, Azma; Thompson, D.J.

doi:10.1016/j.apacoust.2010.06.009

Cited by 64 publications

(30 citation statements)

References 18 publications

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“…Similarly, Zhang and Li [21] gave a detailed formulation of the sound radiation from baffled plates with arbitrary boundary conditions by means of a Fourier series. Results were focused on single mode radiation efficiency and on total radiation efficiency for a forcing point at the centre of the plate.The sensitivity of the radiation efficiency to the location of the forcing point was highlighted by Putra and Thompson in [16]. By comparing the results obtained with twenty different forcing positions they found that the average radiation efficiency lies roughly in the middle of a corridor defined by the 10 th and 90 th percentile and the width of such a corridor can be up to 20 dB at low frequency, decreasing 7 towards the critical frequency.…”

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confidence: 93%

“…The sensitivity of the radiation efficiency to the location of the forcing point was highlighted by Putra and Thompson in [16]. By comparing the results obtained with twenty different forcing positions they found that the average radiation efficiency lies roughly in the middle of a corridor defined by the 10 th and 90 th percentile and the width of such a corridor can be up to 20 dB at low frequency, decreasing 7 towards the critical frequency.…”

mentioning

confidence: 93%

“…Clearly, having a velocity field equal to zero everywhere, apart from the plate surface, makes the problem easier to solve, but this is not always fully representative of a real structure. For this reason, the problem of an unbaffled plate has also been investigated by some authors ( [16], [19] and [21][22][23][24]). Some semi-analytical methods have been proposed and the effect of boundary conditions on unbaffled plates has also been addressed ( [16] and [23]).…”

Section: Snyder and Tanakamentioning

confidence: 99%

“…For this reason, the problem of an unbaffled plate has also been investigated by some authors ( [16], [19] and [21][22][23][24]). Some semi-analytical methods have been proposed and the effect of boundary conditions on unbaffled plates has also been addressed ( [16] and [23]). In particular, results shown in [16] have shown that, in adopting simply supported and/or guided boundary conditions, the variability in radiation efficiency of an unbaffled plate is much lower than the corresponding baffled plate.…”

Section: Snyder and Tanakamentioning

confidence: 99%

“…By following the same method and adopting numerical techniques Yoo [15] explored also the effect of guided boundary conditions. Putra and Thompson [16] also considered the difference between simply supported and guided boundary conditions for both baffled and unbaffled plates.…”

Section: Snyder and Tanakamentioning

confidence: 99%

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The effect of different combinations of boundary conditions on the average radiation efficiency of rectangular plates

Squicciarini

Thompson

Corradi

2014

Journal of Sound and Vibration

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The boundary conditions of a vibrating plate are known to have an influence on its sound radiation for frequencies below the critical frequency. To investigate this effect in a systematic way, the average radiation efficiency and radiated power are calculated for a rectangular plate set in an infinite baffle using a modal summation approach. Whereas analytical expressions exist for simply supported boundary conditions, a numerical approach is required for other cases. Nine combinations of boundary conditions are considered, consisting of simply supported, clamped and free edges on different plate edges. The structural vibration is approximated by using independent beam functions in orthogonal directions allowing simple approximate formulae for mode shapes and natural frequencies.This assumption is checked against a finite element model and shown to give reliable results. It is shown that a free plate has the lowest radiation efficiency and a clamped plate the highest for most frequencies between the fundamental panel natural frequency and the critical frequency. Other combinations of boundary condition give intermediate results according to the level of constraint introduced. The differences depend on frequency: excluding the extreme case of a fully free plate all the other boundary conditions give results within a range of 8 dB in the middle part of the shortcircuiting region, decreasing towards the critical frequency. At low frequency the differences can be even greater, in some cases up to 20 dB. These conclusions are shown to hold for a range of plate thicknesses and dimensions.Keywords: plate vibration, baffled plates, radiation efficiency, radiation ratio, boundary condition. IntroductionIn many engineering applications it is important to be able to estimate the noise radiated by a vibrating structure during its design stage. In most cases the structures under consideration, whether industrial machinery, vehicles or civil structures such as bridges, can be subdivided into smaller components; thin vibrating panels, strips and beams are often important components that are 3 responsible for noise radiation. To evaluate the noise produced a common procedure is to evaluate the vibration velocity levels of each component and to estimate their acoustic power levels through their dimensions and radiation efficiency. It is particularly useful to study the radiation efficiency of the elementary components in order to be able to characterise the acoustic performance of the structure they form.The radiation efficiency of an object at a given frequency or frequency band can be defined as the radiated sound power rad W , normalized by the radiating area S, the air density  , the speed of sound c and the space-averaged mean square vibration velocity The denominator in eq. (1) represents the power that would be radiated by a surface area S, vibrating as a rigid piston to produce plane waves, with a mean square velocity equal to the surface-averaged mean-square velocity of the actual object. Furthermore, if the me...

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confidence: 93%

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confidence: 93%

Section: Snyder and Tanakamentioning

confidence: 99%

Section: Snyder and Tanakamentioning

confidence: 99%

Section: Snyder and Tanakamentioning

confidence: 99%

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The effect of different combinations of boundary conditions on the average radiation efficiency of rectangular plates

Squicciarini

Thompson

Corradi

2014

Journal of Sound and Vibration

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Multiphysical theoretical prediction and experimental verification of vibroacoustic responses of fruit fiber‐reinforced polymeric composite

2020

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The acoustic parameters (sound power level and radiation efficiency) of harmonically excited natural fiber (Luffa cylindrica) reinforced polymer composite panel is predicted first time using a coupled finite and boundary element scheme including the mechanical characteristics. First, the frequency values of the freely vibrating Luffa fiber-reinforced composite are obtained through a finite element solution considering the higher-order polynomial kinematic theory to count the structural deformation. Further, the Helmholtz wave equation is solved to evaluate the acoustic data under the harmonic excitation. The proposed multiphysics model is taking care of the structure, the fluid medium and the coupling between them, which, in turn, allows to obtain the solution numerically for the final finished polymer composite product. Further, the model accuracy has been shown by comparing both frequency and sound radiation responses with available published results including the own experimental values. Moreover, the fruit extracted fiber reinforced polymer composite plate components are fabricated using different volume fractions of fiber content and utilized for the numerical analysis considering their experimental properties (mechanical and physical). Finally, the influences of the dimensional variable (aspect ratio, side to thickness ratio and support condition) on the acoustic radiation behavior of the fabricated composite have been examined thoroughly to show their possible real-life applications.

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Comparison of Vibration and Noise Characteristics of Urban Rail Transit Bridges with Box-Girder and U-Shaped Sections

Li¹,

Huang²,

Thompson³

2021

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Rolling noise and structure-borne noise from rail transit viaducts often lead to complaints from nearby residents. Concrete box section bridges are commonly adopted for the viaducts but those with U-shaped sections have become popular recently due to their more attractive form and reduced visual impact. One question that often arises in relation to the choice of the section types is their relative noise performance. This study aims to compare the vibration and noise characteristics of concrete bridges with different sections in a systematic way by using the same noise prediction method. A coupled track-bridge model is introduced to obtain the rail vibration and the power input to the bridge through the rail fasteners. A threedimensional vibro-acoustic finite element method is applied to obtain the noise radiated from the bridge and the rail subjected to sets of multiple forces acting on them. This is determined in terms of the radiation efficiency and sound pressure transfer functions for arbitrary forcing. The averaged mean squared vibration velocity of the coupled wheel-track-bridge model subjected to roughness excitation is used to scale the noise from the acoustic model. The method is validated by comparison with field measurements of noise from a U-shaped bridge in Shanghai.Comparative investigations are then conducted of the U-shaped bridge, a box girder bridge with 2 single cell and a twin-box girder bridge with two cells; each is fitted with equivalent noise barriers. It is found in each case that the noise from the rail is about 10 dB(A) larger than the bridge noise at positions to the side of the bridge. The U-shaped girder generally leads to slightly lower total noise levels than the box girders, with differences of less than 1 dB(A) when they have noise barriers of the same height. In terms of the bridge noise, however, the singlebox and twin-box girders produce an average of 8.6 and 11.7 dB(A) less noise than the Ushaped girder.

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Sound radiation from rectangular baffled and unbaffled plates

Cited by 64 publications

References 18 publications

The effect of different combinations of boundary conditions on the average radiation efficiency of rectangular plates

The effect of different combinations of boundary conditions on the average radiation efficiency of rectangular plates

Multiphysical theoretical prediction and experimental verification of vibroacoustic responses of fruit fiber‐reinforced polymeric composite

Comparison of Vibration and Noise Characteristics of Urban Rail Transit Bridges with Box-Girder and U-Shaped Sections

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