The use of a functional basis to calculate acoustic transmission between rooms

Gagliardini, Laurent; Roland, J.; Guyader, Jean‐Louis

doi:10.1016/0022-460x(91)90114-y

Cited by 46 publications

(39 citation statements)

References 21 publications

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“…A key issue in the modal expansions is to decide which and how many functions are taken into account (see the paper of Gagliardini et al [23]). This question also arises regarding the trigonometric functions used in finite layer methods.…”

Section: Truncating the Trigonometric Seriesmentioning

confidence: 99%

The finite layer method for modelling the sound transmission through double walls

Díaz-Cereceda

Poblet-Puig

Ferran

2012

Journal of Sound and Vibration

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The finite layer method (FLM) is presented as a discretisation technique for the computation of noise transmission through double walls. It combines a finite element method (FEM) discretisation in the direction perpendicular to the wall with trigonometric functions in the two in-plane directions. It is used for solving the Helmholtz equation at the cavity inside the double wall, while the wall leaves are modelled with the thin plate equation and solved with modal analysis. Other approaches to this problem are described here (and adapted where needed) in order to compare them with the FLM. They range from impedance models of the double wall behaviour to different numerical methods for solving the Helmholtz equation in the cavity. For the examples simulated in this work (impact noise and airborne sound transmission), the former are less accurate than the latter at low frequencies. The main advantage of FLM over the other discretisation techniques is the possibility of extending it to multilayered structures without changing the interpolation functions and with an affordable computational cost. This potential is illustrated with a calculation of the noise transmission through a multilayered structure: a double wall partially filled with absorbing material.

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Section: Truncating the Trigonometric Seriesmentioning

confidence: 99%

The finite layer method for modelling the sound transmission through double walls

Díaz-Cereceda

Poblet-Puig

Ferran

2012

Journal of Sound and Vibration

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“…For this reason, models that use analytical modal analysis in the acoustic domains in order to reduce the computational costs (e.g. [9][10][11]) cannot be used. The floor is composed of a wood board and I-shaped beams (73 mm in width and 140 mm in height).…”

Section: The Role Of Beams In the Radiation Of A Surfacementioning

confidence: 99%

Numerical modelling of the radiation efficiency of asymmetrical structures

et al. 2009

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The radiation efficiency of a structural element is required by some models in order to predict its sound insulation. A common assumption is that the radiation on both sides of the element is the same. This is not true for asymmetrical structural elements like lightweight floors consisting of a beam-supported flat board. The radiation efficiency is larger on the beam side, because the beams act as exciters and increase the pressure level in the room. These different radiation efficiencies are calculated here for a two-dimensional cross-section by using finite elements and boundary elements. The obtained preliminary results illustrate that considering a single radiation efficiency can be a source of errors and that further investigation is required in order to improve predictions.

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“…By analysis of the model predictions, it is found that the finite dimensions of the plate result in a semi-discrete coincidence phenomenon, i.e., the wavelength of a mode shape of the rib-stiffened plate is close to the free acoustic wavelength at the corresponding natural frequency. This is seen to result in an oscillating narrow-band transmission loss over a wide frequency range, which is in contrast to the discrete coincidence phenomenon for finite homogenous isotropic plates [4,7]. Only a few of the plate modes in this wide frequency range exhibit semi-discrete coincidence, which suggests that the sound insulation in that frequency range can be substantially increased by suppressing only a few structural modes.…”

Section: Introductionmentioning

confidence: 99%

Semi-Discrete Coincidence in the Mid-Frequency Sound Transmission Through Rib-Stiffened Panels

Reynders¹,

hoorickx²,

Dijckmans³

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. Plates with attached beams or ribs, rather than monolithic plates, are commonly employed in civil and mechanical engineering for reasons of weight and static stiffness. Unfortunately, attaching stiffeners to a plain plate generally increases its radiation efficiency and reduces its airborne sound insulation. This contribution aims at gaining insight into the sound insulation of rib-stiffened plates in the mid-frequency range, where the modal behavior of the plate is still important, but the neighboring sound fields can already be considered as diffuse. A detailed finite element model of a PMMA plate with steel stiffeners attached is constructed and coupled to a reverberant sound field model of the adjoining room(s) within the recently developed hybrid finite element -statistical energy analysis framework. This framework is computationally very efficient, it enables to compute the coupling loss factors between the sound fields in a rigorous, straight forward way, and the uncertainties due to random wave scattering -which is the physical origin of the diffuse field -can be quantified. The finite element model of the plate is first calibrated by minimizing the difference between its lowest natural frequencies and mode shapes and the corresponding measured values. The hybrid model is then employed for predicting the sound reduction index across the building acoustics frequency range. These predictions are validated against airborne sound insulation measurements. Within a wide frequency range, pronounced dips are observed at specific natural frequencies of the plate, at which the wavelength of the corresponding mode shape is close to the free acoustic wavelength. Since there is an obvious connection with the coincidence phenomenon for infinite plates, the observed phenomenon is termed the semi-discrete coincidence phenomenon. It is shown that in the mid-frequency range, an important increase in airborne sound insulation can be achieved by suppressing only a few particular resonances of the considered rib-stiffened plate.7620

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The use of a functional basis to calculate acoustic transmission between rooms

Cited by 46 publications

References 21 publications

The finite layer method for modelling the sound transmission through double walls

The finite layer method for modelling the sound transmission through double walls

Numerical modelling of the radiation efficiency of asymmetrical structures

Semi-Discrete Coincidence in the Mid-Frequency Sound Transmission Through Rib-Stiffened Panels

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