Sound Transmission Loss of Adhesively Bonded Sandwich Panels with Pyramidal Truss Core: Theory and Experiment

In this paper, an analytical model is developed to investigate sound transmission loss characteristic of adhesively bonded metal sandwich panels with pyramidal lattice truss cores based on 3D elasticity theory. Meanwhile, practical specimen is fabricated to conduct corresponding sound insulation experiment test via a standing wave tube method. The effective elastic constant of truss cores is derived using one homogenization theory on account of equivalent strain energy. It is found that satisfactory agreement is achieved between theoretical solutions and experiment results, and damping effect of adhesive bonding interface between facesheets and core has a great impact on transmission loss. Further parameter investigations demonstrate the significant effect of the elevation and azimuth angles of the pyramidal cores, which can be conveniently changed to tailor the acoustic performance of the sandwich panels in the whole frequency range.

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Analysis of the transmission loss of double-leaf panels with an equivalent spring–mass model for studs

Journal of Mechanics ◽

10.1093/jom/ufaa020 ◽

2020 ◽

Vol 37 ◽

pp. 126-133

Author(s):

Yuan-Wei Li ◽

Chao-Nan Wang

Keyword(s):

Distribution Curve ◽

Transmission Loss ◽

Sound Transmission ◽

Experimental Results ◽

Sound Insulation ◽

Sound Transmission Loss ◽

Mass Model ◽

Steel Stud ◽

Panel Thickness ◽

Stiffness Distribution

Abstract The purpose of this study was to investigate the sound insulation of double-leaf panels. In practice, double-leaf panels require a stud between two surface panels. To simplify the analysis, a stud was modeled as a spring and mass. Studies have indicated that the stiffness of the equivalent spring is not a constant and varies with the frequency of sound. Therefore, a frequency-dependent stiffness curve was used to model the effect of the stud to analyze the sound insulation of a double-leaf panel. First, the sound transmission loss of a panel reported by Halliwell was used to fit the results of this study to determine the stiffness of the distribution curve. With this stiffness distribution of steel stud, some previous proposed panels are also analyzed and are compared to the experimental results in the literature. The agreement is good. Finally, the effects of parameters, such as the thickness and density of the panel, thickness of the stud and spacing of the stud, on the sound insulation of double-leaf panels were analyzed.

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Prediction of Sound Transmission Loss for Finite Sandwich Panels Based on a Test Procedure on Beam Elements

Journal of Vibration and Acoustics ◽

10.1115/1.4023842 ◽

2013 ◽

Vol 135 (6) ◽

Cited By ~ 7

Author(s):

Zhongchang Qian ◽

Daoqing Chang ◽

Bilong Liu ◽

Ke Liu

Keyword(s):

Sandwich Panel ◽

Transmission Loss ◽

Test Procedure ◽

Sandwich Panels ◽

Sound Transmission ◽

Expansion Method ◽

Bending Stiffness ◽

Sound Transmission Loss ◽

Modal Expansion ◽

Beam Elements

An approach on the prediction of sound transmission loss for a finite sandwich panel with honeycomb core is described in the paper. The sandwich panel is treated as orthotropic and the apparent bending stiffness in two principal directions is estimated by means of simple tests on beam elements cut from the sandwich panel. Utilizing orthotropic panel theory, together with the obtained bending stiffness in two directions, the sound transmission loss of simply-supported sandwich panel is predicted by the modal expansion method. Simulation results indicated that dimension, orthotropy, and loss factor may play important roles on sound transmission loss of sandwich panel. The predicted transmission loss is compared with measured data and the agreement is reasonable. This approach may provide an efficient tool to predict the sound transmission loss of finite sandwich panels.

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Non-Wovens as Sound Reducers

Latvian Journal of Physics and Technical Sciences ◽

10.2478/lpts-2018-0014 ◽

2018 ◽

Vol 55 (2) ◽

pp. 64-76

Author(s):

D. Belakova ◽

A. Seile ◽

S. Kukle ◽

T. Plamus

Keyword(s):

Absorption Coefficient ◽

Surface Density ◽

Sound Absorption ◽

Transmission Loss ◽

Sound Transmission ◽

Sound Insulation ◽

Material Structure ◽

Sound Transmission Loss ◽

Sound Waves ◽

Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

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Acoustic performance prediction of a multilayered finite cylinder equipped with porous foam media

Journal of Vibration and Control ◽

10.1177/1077546319890025 ◽

2020 ◽

Vol 26 (11-12) ◽

pp. 899-912 ◽

Cited By ~ 6

Author(s):

Hamed Darvish Gohari ◽

MohamdReza Zarastvand ◽

Roohollah Talebitooti

Keyword(s):

Transmission Loss ◽

Shear Deformation Theory ◽

Sound Transmission ◽

Double Fourier Series ◽

Finite Cylinder ◽

Sound Insulation ◽

Transverse Displacement ◽

Sound Transmission Loss ◽

Insulation Property ◽

Longitudinal Modes

This paper presents an analytical model to embed porous materials in a finite cylindrical shell in order to obtain the sound transmission loss coefficient. Although the circumferential modes are considered only for calculating the amount of the transmitted noise through an infinitely long cylinder, the present study employs the longitudinal modes in addition to circumferential ones to analyze the vibroacoustic performance of a simply supported cylinder subjected to the porous core based on the first order shear deformation theory. To achieve this goal, the structure is immersed in a fluid and excited by an acoustic wave. In addition, the acoustic pressures and the displacements are developed in the form of double Fourier series. Since these series consist of infinite modes, it is essential to terminate this process by considering adequate modes. Hence, the convergence checking algorithm is employed in the form of some three-dimensional configurations with respect to length, frequency and radius. Afterwards, some figures are plotted to confirm the accuracy of the present formulation. In these configurations, the obtained sound transmission loss from the present study is compared with that of the infinite one. It is shown that by increasing the length of the structure, the results are approached to sound transmission loss of the infinite shells. Moreover, a new approach is proposed to show the transverse displacement of a finite poroelastic cylinder at different frequencies. Based on the outcomes, it is found that by enhancing the length of the poroelastic cylinder, the amount of the transmitted sound into the structure is reduced at the high frequency domain. However, the sound insulation property of the structure is improved at the low frequency region when the radius of the shell is decreased.

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Sound transmission loss characteristics of unbounded orthotropic sandwich panels in bending vibration considering transverse shear deformation

Composite Structures ◽

10.1016/j.compstruct.2010.04.014 ◽

2010 ◽

Vol 92 (12) ◽

pp. 2885-2889 ◽

Cited By ~ 25

Author(s):

Wang Shengchun ◽

Deng Zhaoxiang ◽

Shen Weidong

Keyword(s):

Shear Deformation ◽

Transverse Shear ◽

Transmission Loss ◽

Sandwich Panels ◽

Sound Transmission ◽

Transverse Shear Deformation ◽

Sound Transmission Loss ◽

Bending Vibration

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Predicting the Sound Transmission Loss of Honeycomb Panels using the Wave Propagation Approach

Acta Acustica united with Acustica ◽

10.3813/aaa.918466 ◽

2011 ◽

Vol 97 (5) ◽

pp. 869-876 ◽

Cited By ~ 6

Author(s):

Sathish Kumar ◽

Leping Feng ◽

Ulf Orrenius

Keyword(s):

Wave Propagation ◽

Transmission Loss ◽

Plate Theory ◽

Sandwich Panels ◽

Sound Transmission ◽

Structural Vibration ◽

Sound Transmission Loss ◽

Resonance Frequencies ◽

Fluid Coupling ◽

Vibration And Sound Radiation

The sound transmission properties of sandwich panels can be predicted with sufficient degree of accuracy by calculating the wave propagation properties of the structure. This method works well for sandwich panels with isotropic cores but applications to panels with anisotropic cores are hard to find. Honeycomb is an example of anisotropic material which when used as a core, results in a sandwich panel with anisotropic properties. In this paper, honeycomb panels are treated as being orthotropic and the wavenumbers are calculated for the two principle directions. These calculated wavenumbers are validated with the measured wavenumbers estimated from the resonance frequencies of freely hanging honeycomb beams. A combination of wave propagation and standard orthotropic plate theory is used to predict the sound transmission loss of honeycomb panels. These predictions are validated through sound transmission measurements. Passive damping treatment is a common way to reduce structural vibration and sound radiation, but they often have little effect on sound transmission. Visco-elastic damping with a constraining layer is applied to two honeycomb panels with standard and enhanced fluid coupling properties. This enhanced fluid coupling in one of the test panels is due to an extended coincidence range observed from the dispersion curves. The influence of damping treatments on the sound transmission loss of these panels is investigated. Results show that, after the damping treatment, the sound transmission loss of an acoustically bad panel and a normal panel are very similar.

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Low-Frequency Broadband Sound Transmission Loss of Infinite Orthogonally Rib-Stiffened Sandwich Structure with Periodic Subwavelength Arrays of Shunted Piezoelectric Patches

Shock and Vibration ◽

10.1155/2017/2791351 ◽

2017 ◽

Vol 2017 ◽

pp. 1-17 ◽

Cited By ~ 1

Author(s):

Zhifu Zhang ◽

Weiguang Zheng ◽

Qibai Huang

Keyword(s):

Sandwich Structure ◽

Transmission Loss ◽

Virtual Work ◽

Low Frequency ◽

Sound Transmission ◽

Sound Insulation ◽

Convergence Criterion ◽

Sound Transmission Loss ◽

Space Harmonic ◽

Broadband Sound

This paper studies low-frequency sound transmission loss (STL) of an infinite orthogonally rib-stiffened sandwich structure flexibly connected with periodic subwavelength arrays of finite shunted piezoelectric patches. A complete theoretical model is proposed by three steps. First, the panels and piezoelectric patches on both sides are equivalent to two homogeneous facesheets by effective medium method. Second, we take into account all inertia terms of the rib-stiffeners to establish the governing equations by space harmonic method, separating the amplitude coefficients of the equivalent facesheets through virtual work principle. Third, the expression of STL is reduced. Based on the two prerequisites of subwavelength assumption and convergence criterion, the accuracy and validity of the model are verified by finite element simulations, cited experiments, and theoretical values. In the end, parameters affecting the STL performance of the structure are studied. All of these results show that the sandwich structure can improve the low-frequency STL effectively and broaden the sound insulation bandwidth.

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ON THE SOUND TRANSMISSION LOSS OF CAVITY PANELS AND RESILIENT-MATERIAR-SANDWICH PANELS : Study on Sound Transmission Loss of Building Elements Part 3

Transactions of the Architectural Institute of Japan ◽

10.3130/aijsaxx.116.0_42 ◽

1965 ◽

Vol 116 (0) ◽

pp. 42-51,67

Author(s):

SHINICHI KUGA

Keyword(s):

Transmission Loss ◽

Sandwich Panels ◽

Sound Transmission ◽

Sound Transmission Loss ◽

Building Elements

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An improved approach for normal-incidence sound transmission loss measurement using a four-microphone impedance tube

Journal of Vibration and Control ◽

10.1177/1077546320926905 ◽

2020 ◽

pp. 107754632092690

Author(s):

Zechao Li ◽

Sizhong Chen ◽

Zhicheng Wu ◽

Lin Yang

Keyword(s):

Transfer Matrix ◽

Sound Absorption ◽

Transmission Loss ◽

Sound Transmission ◽

Normal Incidence ◽

Sound Insulation ◽

Sound Transmission Loss ◽

The Common ◽

Wavefield Decomposition ◽

Insulation Performance

The main aim of this study is to introduce an improved method for determining the sound properties of acoustic materials which is more precise than the common wavefield decomposition method and simpler than the common transfer matrix method. In the first part of the article, a group of formulae for calculating sound transmission loss is represented by combining the wavefield decomposition and transfer matrix methods. Subsequently, a formula for calculating sound absorption coefficients is derived from these formulae by definition. Furthermore, the present formulae are validated by comparing the experimental results achieved with the present formulae and those results obtained by other methods recorded in published articles. Eventually, it is demonstrated that the method can accurately measure the sound insulation performance of materials and the sound absorption properties of limp and lightweight materials.

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