Low Frequency Acoustic Performance of Close-Fitting Sandwich Panels

1998 ◽  
Vol 5 (3) ◽  
pp. 143-161 ◽  
Author(s):  
W.C. Tang ◽  
C.F. Ng
Keyword(s):  
Porous Material ◽  
Low Frequency ◽  
Coupled System ◽  
Sound Insulation ◽  
Flexible Plate ◽  
Cavity Depth ◽  
Acoustic Cavity ◽  
Air Cavities ◽  
Rigid Walls ◽  
Double Wall

The experiment presented in this paper was to investigate and analyse the noise reduction at low frequency of porous material used to line the cavity between two panels of a double-panel structure. The effects of panel construction, fibreglass and cavity depth have also been studied. The structural-acoustic coupled system of a sandwich structure, backed by a rectangular acoustic cavity of rigid walls is discussed. It is found that the sound insulation of a combination of a stiff thick and a thin flexible plate panel, with air cavities and porous material in-between, is more effective than that of the conventional double-wall panel at low frequency.

Global Active Control of Transmitted Sound Into Acoustic Cavity With Speakers and Piezoelectric Patch Actuators

2009 ◽  
Author(s):  
Masih Hanifzadegan ◽  
Abdolreza Ohadi
Keyword(s):  
Active Control ◽  
Plane Waves ◽  
Sound Field ◽  
Coupled System ◽  
Mode Shapes ◽  
Flexible Plate ◽  
Acoustic System ◽  
Acoustic Cavity ◽  
Piezoelectric Patch ◽  
Rigid Walls

In this work modeling of a vibro-acoustic system and global sound field control with both acoustic and structural actuators have been studied. The model of the system consists of a 3D rectangular cavity with five acoustically rigid walls and a flexible plate on the top of cavity. First, modeling of the vibro-acoustic system has been acquired and subsequently the mode shapes and natural frequencies of the coupled system have been calculated. Plane waves on the plate surface are the main sources of disturbances in this system. Undesired sound (noise) which is propagated into the enclosure is controlled by mounted piezoelectric patch actuators on the plate and acoustic piston sources (speakers) inside cavity. The global active control is designed to minimize the acoustic potential energy inside the cavity. The control performance has been investigated by acoustic and structural actuators separately and simultaneously.

Analysis of Vehicle Interior Low-Frequency Noise Based on ATV

2014 ◽  
Vol 494-495 ◽  
pp. 78-81
Author(s):  
Long Ma ◽  
Wen Feng Xia
Keyword(s):  
Acoustic Pressure ◽  
Ride Comfort ◽  
Low Frequency ◽  
Coupled System ◽  
The Body ◽  
Frequency Noise ◽  
Vehicle Interior ◽  
Fem Model ◽  
Acoustic Structure ◽  
Acoustic Cavity

The FEM model of the body and acoustic cavity are created, and the acoustic-structure coupled system is built up,and the SPL(sound press level) of points corresponding to the drivers ear and passengers ears were calculated using software LMS.virtual.lab. And there are several relatively noticeable acoustic pressure peaks around 60Hz, 102Hz, 120Hz and 168Hz. The maximum noise value was calculated by using the method of ATV method, several suggestions are advised to decrease the vehicle interior noise so that the vehicle ride comfort could be improved.

Experimental Verification of the Asymptotic Modal Analysis Method as Applied to a Rectangular Acoustic Cavity Excited by Structural Vibration

1992 ◽  
Vol 114 (4) ◽  
pp. 546-554 ◽  
Author(s):  
L. F. Peretti ◽  
E. H. Dowell
Keyword(s):  
Modal Analysis ◽  
Sound Pressure ◽  
Power Spectra ◽  
Rigid Wall ◽  
Structural Vibration ◽  
Flexible Plate ◽  
Acoustic Cavity ◽  
Rigid Walls ◽  
End Wall ◽  
Good Agreement

An experiment was performed on a rigid wall rectangular acoustic cavity driven by a flexible plate mounted in a quarter of one end wall and excited by white noise. The experiment was designed so that the assumptions of Asymptotic Modal Analysis (AMA) were satisfied for certain bandwidths and center frequencies. Measurements of sound pressure levels at points along the boundaries and incrementally into the interior were taken. These were compared with the theoretical results predicted with AMA, and found to be in good agreement, particularly for moderate (1/3 octave) bandwidths and sufficiently high center frequencies. Sound pressure level measurements were also taken well into the cavity interior at various points along the 5 totally rigid walls. The AMA theory, including boundary intensification effects, was shown to be accurate provided the assumption of large number of acoustic modes is satisfied, and variables such as power spectra of the wall acceleration, frequency, and damping are slowly varying in the frequency bandwidth.

Sound Transmission Through a Double-Wall Structure Coupled with Two Trapezoidal Acoustic Cavities

2016 ◽  
Vol 08 (08) ◽  
pp. 1650100 ◽  
Author(s):  
Haosen Yang ◽  
Hui Zheng ◽  
Xiang Xie
Keyword(s):  
Theoretical Model ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Wall Structure ◽  
Acoustic System ◽  
Acoustic Cavity ◽  
Acoustic Cavities ◽  
Insulation Performance ◽  
Double Wall

This paper aims at investigating the sound transmission mechanism of a flexibly-linked finite length double-wall structure. The problem stems from the modeling of sound transmission through corrugated core sandwich panels for predicting its transmission loss. The spatial segmentation of the acoustic gap and fully structure-acoustic coupling effect between the flexural vibration of the inclined mechanical link and the two adjacent trapezoidal acoustic cavities are considered. The theoretical model of the considered vibro-acoustic system is developed by using the modal superposition method in conjunction with envelope rectangular technique. Based on the developed theoretical model, the general vibro-acoustics characteristics of the system is presented. Particularly by using the [Formula: see text] mode of the acoustic cavity and the first structural modal frequency, the ratio between the aerostatic stiffness and the structural stiffness is formulated, and a criterion is proposed to determine whether the sound insulation performance of the vibro-acoustic system is controlled mainly by the structure or the acoustic cavity. Numerical investigations reveal that with different stiffness ratio, the acoustic cavity affects the sound transmission through both the added stiffness and added mass following different mechanisms. Besides, the influence of the inclined angle of the connecting beam on sound insulation performance of the double-wall structure is also studied. The obtained results are believed to be helpful in the optimal design of corrugated core sandwich panels for sound insulation.

Influence of the Flexible Plate with a Space Structure on the Sound Insulation Improvement

2020 ◽  
pp. 14-18
Author(s):  
N.A. KOCHKIN ◽  
◽  
I.L. SHUBIN ◽  
A.A. KOCHKIN ◽  
◽  
...  
Keyword(s):  
Space Structure ◽  
Sound Insulation ◽  
Flexible Plate

scholarly journals Study on broadband low-frequency sound insulation of multi-channel resonator acoustic metamaterials

AIP Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 045321
Author(s):  
Chi Xu ◽  
Hui Guo ◽  
Yinghang Chen ◽  
Xiaori Dong ◽  
Hongling Ye ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Acoustic Metamaterials ◽  
Frequency Sound

Low-frequency sound absorption of a tunable multilayer composite structure

2021 ◽  
pp. 107754632110082
Author(s):  
Hanbo Shao ◽  
Jincheng He ◽  
Jiang Zhu ◽  
Guoping Chen ◽  
Huan He
Keyword(s):  
Porous Material ◽  
Absorption Coefficient ◽  
Composite Structure ◽  
Low Frequency ◽  
Acoustic Absorption ◽  
Multilayer Composite ◽  
Absorption Frequency ◽  
Acoustic Absorption Coefficient ◽  
Simulation And Experiment ◽  
Single Material

Our work investigates a tunable multilayer composite structure for applications in the area of low-frequency absorption. This acoustic device is comprised of three layers, Helmholtz cavity layer, microperforated panel layer, and the porous material layer. For the simulation and experiment in our research, the absorber can fulfill a twofold requirement: the acoustic absorption coefficient can reach near 0.8 in very low frequency (400 Hz) and the range of frequency is very wide (400–3000 Hz). In all its absorption frequency, the average of the acoustic absorption coefficient is over 0.9. Besides, the absorption coefficient can be tunable by the scalable cavity. The multilayer composite structure in our article solved the disadvantages in single material. For example, small absorption coefficient in low frequency in traditional material such as microperforated panel and porous material and narrow reduction frequency range in acoustic metamaterial such as Helmholtz cavity. The design of the composite structure in our article can have more wide application than single material. It can also give us a novel idea to produce new acoustic devices.

Ventilated metamaterials for broadband sound insulation and tunable transmission at low frequency

2021 ◽  
pp. 101348
Author(s):  
Zhenqian Xiao ◽  
Penglin Gao ◽  
Dongwei Wang ◽  
Xiao He ◽  
Linzhi Wu
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Broadband Sound

Sound transmission through triple plates separated by air cavities in the low-frequency range

2018 ◽  
Vol 230 (3) ◽  
pp. 965-977
Author(s):  
Akintoye Olumide Oyelade ◽  
Obanishola Mufutau Sadiq ◽  
Omotayo A. Fakinlede
Keyword(s):  
Low Frequency ◽  
Sound Transmission ◽  
Frequency Range ◽  
Air Cavities

Ceiling Construction Low-Frequency Noise Issues

2013 ◽  
Vol 649 ◽  
pp. 277-280
Author(s):  
Petra Berková ◽  
Pavel Berka
Keyword(s):  
Spectral Analysis ◽  
Low Frequency ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Frequency Tone ◽  
The Impact ◽  
40 Hz

Through the use of a spectral analysis of the source of noise – person’s movement over the ceiling construction – it was found out that in this kind of noise distinctive low-frequency tone components occur (31,5 - 40 Hz) which is beyond the evaluation area of the impact sound insulation of the ceiling construction, s. [2], [3].

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