Experimental Study of Sound Transmission Loss in Electrorheological Liquids

2002 ◽  
Author(s):  
Marek L. Szary ◽  
Maciej Noras
Keyword(s):  
Electric Field ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Active Vibration Control ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Frequency Range ◽  
Field Density ◽  
Active Vibration ◽  
College Of Engineering

Electrorheological (ER) liquids possess the ability to change their physical properties like the apparent viscosity and modulus of elasticity under the influence of an external electric field. They serve successfully in the field of active vibration control—as well as in many other areas. In the Acoustic Laboratory at the College of Engineering, Southern Illinois University in Carbondale, research on the possibility of applying ER liquids to the control of a sound transmission loss (STL) was conducted. The STL was investigated for various kinds of ER suspensions in the frequency range 100 Hz to 2 kHz. An influence of the electric field density on the STL was different for normal and shear stress developed by DC voltage. In both cases the STL decreased with the increasing electric field density. These properties could be potentially useful in sound propagation control applications.

scholarly journals Non-Wovens as Sound Reducers

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).

Active Vibration Control for the Improvement of Sound Transmission Loss through a Square Plate

2002 ◽  
Vol 9 (4) ◽  
pp. 289-301 ◽  
Author(s):  
Kuo-Tsai Chen ◽  
Kuan-Tin Chiang ◽  
Sue-Min Huang ◽  
Bor-Chien Tsai
Keyword(s):  
Vibration Control ◽  
Control Algorithm ◽  
Transmission Loss ◽  
Active Vibration Control ◽  
Sound Transmission ◽  
Resonant Frequencies ◽  
Active Vibration ◽  
Square Plate ◽  
Reverberant Field ◽  
Adaptive Control Algorithm

An active vibration control system is considered for the reduction of sound transmission through a square plate acted on by a reverberant field. The study includes the prediction of the resonant frequencies of the plate involved, the derivations of both the feedback adaptive control algorithm and the volume velocity cancellation technique adopted, and the experiment for active vibration control on the sound transmission through a plate. It is demonstrated that an improvement of the order of 6 decibels at 132 Hz is obtained. Also, increased transmission loss at lower resonant frequencies is possible.

Sound Transmission Loss in Electrorheological Fluids Under DC Voltage

2000 ◽  
Author(s):  
Marek L. Szary ◽  
Maciej Noras
Keyword(s):  
Shear Stress ◽  
Sound Pressure ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Electrorheological Fluids ◽  
Sound Transmission Loss ◽  
Dc Voltage ◽  
College Of Engineering ◽  
Er Fluids ◽  
Er Fluid

Abstract Extensive investigations of sound transmission loss (STL) in electrorheological (ER) fluids were conducted in the Acoustics Laboratory in the College of Engineering, Southern Illinois University Carbondale. The STL was investigated for different kinds of ER suspensions in frequency ranges from 100 Hz to 2kHz. Applied DC voltage to the different electrodes allowed normal and shear stress to develop in the ER fluid respectively. The electric field density was variable. Sound transmission loss was obtained by measurement of the sound pressure level in front of and behind the sample. Under both normal and shear stress in ER fluid, STL decreases with increasing stress. Those properties of ER fluids can be useful in noise and vibration control applications.

Characterizing the Sound Insulation of a Specially Orthotropic Multi-Layered Medium

2007 ◽  
Vol 23 (1) ◽  
pp. 63-68 ◽  
Author(s):  
H.-J. Lin ◽  
C.-N. Wang ◽  
Y.-M. Kuo
Keyword(s):  
Boundary Conditions ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Single Layer ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Sound Transmission Class

AbstractThis work explores the sound transmission loss provided by the orthotropic multi-layers to elucidate the sound insulation of FRP (Fiber Reinforced Plastics). Mat is the major material considered in the numerical works. The transfer matrices of a single layer of the orthotropic laminate and the fluid are determined. Further, the boundary conditions on the various interface planes are arranged into matrix form. Combining the transfer matrixes and the boundary conditions and applying the transfer matrix method (TMM) yields the surface impedance and the sound transmission loss. The sound-propagation characteristics are studied. Additionally, the STC (Sound Transmission Class) of FRP and steel are compared and discussed.

scholarly journals Sound Transmission Loss of a Sandwich Plate with Adjustable Core Layer Thickness

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4160
Author(s):  
Tom Ehrig ◽  
Martin Dannemann ◽  
Ron Luft ◽  
Christian Adams ◽  
Niels Modler ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Core Layer ◽  
Constrained Layer Damping ◽  
Sound Transmission Loss ◽  
Frequency Range ◽  
The Core ◽  
Set Up ◽  
Stiffness And Damping

Compressible Constrained Layer Damping (CCLD) is a novel, semi-active, lightweight-compatible solution for vibration mitigation based on the well-known constrained layer damping principle. The sandwich-like CCLD set-up consists of a base structure, a constraining plate, and a compressible open-cell foam core in between, enabling the adjustment of the structure’s vibration behaviour by changing the core compression using different actuation pressures. The aim of the contribution is to show to what degree, and in which frequency range the acoustic behaviour can be tuned using CCLD. Therefore, the sound transmission loss (TL), as an important vibro-acoustic index, is determined in an acoustic window test stand at different actuation pressures covering a frequency range from 0.5 to 5 kHz. The different actuation pressures applied cause a variation of the core layer thickness (from 0.9 d0 to 0.3 d0), but the resulting changes of the stiffness and damping of the overall structure have no significant influence on the TL up to approximately 1 kHz for the analysed CCLD design. Between 1 kHz and 5 kHz, however, the TL can be influenced considerably well by the actuation pressure applied, due to a damping-dominated behaviour around the critical frequency.

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

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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