scholarly journals Design and simulation of multilayer hybrid foam material for acoustic application

2021 ◽  
Vol 12 ◽  
pp. 10
Author(s):  
L. Yuvaraj ◽  
S. Jeyanthi ◽  
Lenin Babu Mailan Chinnapandi ◽  
Elammaran Jayamani
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Noise Control ◽  
Numerical Study ◽  
Characteristic Impedance ◽  
Sound Absorption Coefficient ◽  
Metallic Foam ◽  
Polymeric Foam ◽  
Closed Cell ◽  
The Individual

New acoustic multilayer absorber fabricated by coupling closed-cell metallic foam and open-cell polymeric foam, which aimed to develop a practical use of metallic foam in the noise control application. In prior, the individual sound absorption coefficient of both foam materials with different thicknesses measured by the impedance tube method as per ASTM E-1050. Using inverse characterization technique, the intrinsic properties needed for five parameter models in a numerical study are predicted. The measured characteristic impedance, complex wave propagation, and sound absorption coefficient of the individual foams are in close agreement with the prediction. Subsequently, a different configuration of multilayer absorber is modeled using obtained properties, and their acoustic performance is evaluated. The result indicates that the coupling of polymeric foam with metallic one exhibits enhanced sound absorption and usage of closed-cell metallic foam in noise control material. Furthermore, the result demonstrates that absorption capability entirely relies on the placement of polymeric foam in the configuration. The proposed hybrid multilayer absorber coupled with test bench car for interior acoustic study, where 5–30 dB is reduction is noticed in 1/3rd octave plot.

Estimation and experimental test of the sound-absorption coefficient of a pin-holder structure (Case of sound waves incidence upon the side surfaces of a group of cylinders)

2021 ◽  
Vol 263 (3) ◽  
pp. 3714-3719
Author(s):  
Takamasa Sato ◽  
Shuichi Sakamoto ◽  
Isami Nitta ◽  
Shunsuke Unai ◽  
Takunari Isobe ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Propagation Constant ◽  
Characteristic Impedance ◽  
Physical Property ◽  
Sound Absorption Coefficient ◽  
Accurate Estimation ◽  
Sound Waves ◽  
Acoustic Characteristics ◽  
Measuring Tube

In this study, we conducted theoretical analyses and experiments related to the acoustic characteristics of the situation where sound waves are incident upon the side surfaces of a group of cylinders forming a pin-holder structure. The sound-absorption coefficient, entering its clearance between cylinders through the geometrical dimension of the clearance or the physical property of gas, was calculated. In the analytical model, the gap part of the pin-holder structure was divided into elements and approximated as a gap surrounded by two parallel planes. The characteristic impedance and propagation constant of the approximate gap were obtained and treated as one-dimensional transfer matrices; the sound-absorption coefficient was then calculated using the transfer-matrix method. The calculated value was compared to that obtained in an experiment with a sample prepared using a 3D printer; the sound-absorption coefficient was measured using a 2-microphone impedance-measuring tube. We attempted to make a simple yet accurate estimation of sound-absorption coefficient using these procedures. Our theoretical values displayed a similar tendency to that obtained by experiment.

Study and estimation of sound absorption coefficient of pin holder structure

2021 ◽  
Vol 69 (2) ◽  
pp. 102-111
Author(s):  
Takamasa Satoh ◽  
Shuichi Sakamoto ◽  
Kohta Akamine ◽  
Shunsuke Unai ◽  
Takunari Isobe ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Absorption Coefficient ◽  
Transfer Matrix ◽  
Sound Absorption ◽  
Propagation Constant ◽  
Characteristic Impedance ◽  
Physical Property ◽  
Sound Absorption Coefficient ◽  
Accurate Estimation ◽  
Analysis Model

In this study, a theoretical analysis of the acoustic characteristics of a pin holder structure was conducted. In addition, the sound absorption coefficient, entering its clearance through the geometrical dimension of the clearance or the physical property of air, was calculated. The analysis model approximates the aperture of a pin holder structure as the clearance between two parallel surfaces. Thus, the propagation constant and characteristic impedance were obtained and treated as a one-dimensional transfer matrix. Subsequently, the sound absorption coefficient was calculated using the transfer matrix method and was compared with the experimental results. In the experiment, a two-microphone impedance tube was used to measure the sound absorption coefficient of the test samples. We attempted to perform a simple yet accurate estimation using these procedures. The theoretical analysis values exhibited a similar tendency to that of the experimental values.

A study on the effects of compression of the felt on flow resistance and acoustic characteristics

2021 ◽  
Vol 263 (1) ◽  
pp. 5170-5174
Author(s):  
Yoon-sang Yang ◽  
Seung Lee
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Flow Resistance ◽  
Transmission Loss ◽  
Combustion Engine ◽  
Characteristic Impedance ◽  
Sound Transmission ◽  
Sound Absorption Coefficient ◽  
Sound Transmission Loss ◽  
Acoustic Characteristics

The sound absorbing materials used to reduce automobile interior noise are classified into Felt and PU Foam. Felt are widely used not only in internal combustion engine vehicles but also in Electric Vehicles because they are eco-friendly materials that can be recycled and relatively light. Automotive interior parts manufacture materials in various thicknesses depending on the shape of matched parts. The pressed material changes the density, flow resistance and affects the overall NVH performance of the vehicle. In this study we worked to confirm changes in flow resistance, sound absorption coefficient and sound transmission loss performance among acoustic characteristics based on the compress ratio of Felt. It was confirmed that the larger the compression of Felt, the larger the flow resistance value, thereby affecting the acoustic characteristic impedance, sound absorption coefficient and sound transmission loss.

A Numerical Study of a Method for Estimating Sound Absorption Coefficient under a Synthesized Diffuse Acoustic Field

2016 ◽  
Vol 9 (3) ◽  
pp. 1111-1116
Author(s):  
Olivier Robin ◽  
Celse Kafui Amedin ◽  
Alain Berry ◽  
Noureddine Atalla ◽  
Olivier Doutres ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Acoustic Field ◽  
Sound Absorption ◽  
Numerical Study ◽  
Sound Absorption Coefficient

Experimental Determination of Sound Absorption Coefficients of Four Types of Malaysian Wood

2013 ◽  
Vol 315 ◽  
pp. 577-581 ◽  
Author(s):  
Elammaran Jayamani ◽  
Sinin Hamdan ◽  
Nurizahusna Binti Suid
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Vibration Isolation ◽  
Noise Control ◽  
Sound Intensity ◽  
Sound Absorption Coefficient ◽  
Extraneous Noise ◽  
Isolation Vibration ◽  
American Society ◽  
Human Ear

Currently, one of the important topics in acoustic science is noise control. It is important to control the noise in order to minimize extraneous noise in rooms, buildings, and our environment. Noise control can be achieved by reducing the intensity of sound to the level that is not harmful to human ear. There are four basic principles employed to reduce noise which is absorption, isolation, vibration isolation, and vibration damping. In fact, the most recognized technique to reduce noise is sound absorption on the materials itself. Sound absorption on material such as wood and porous material have been developed and studied by few researchers. Materials that reduce the sound intensity as the sound wave passes through it by the phenomenon of absorption are called sound absorptive materials. There are lot of methods can be used on determining the sound absorption coefficient of materials. In this paper, a preliminary work has been carried out experimentally to determine the sound absorption coefficient of four types of Malaysian wood. They are Tapang (Koompassia excels), Pulai (Alstonai angustiloba), Selunsor merah (Tristianiopsis beccariana) and Jelutong (Dyera polyphylla). The test was performed using the ASTM E1050-98/ISO 10534-2 (American Society for Testing and Material) standards for the sound absorption coefficient testing. This method is known as impedance tube method (Two-Microphone Method). The absorption coefficient depends on the frequencies. In this study the values of the frequencies used was in the range from 350 Hz to 1000 Hz.

scholarly journals Acoustic Panels Made of Paper Sludge and Clay Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 637
Author(s):  
Tomas Astrauskas ◽  
Tomas Januševičius ◽  
Raimondas Grubliauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Core Material ◽  
Paper Sludge ◽  
Frequency Range ◽  
Absorption Properties ◽  
Air Gaps ◽  
The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

scholarly journals Air permeability and sound absorption coefficient changes from ultrasonic treatment in a cross section of Malas (Homalium foetidum)

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Chun-Won Kang ◽  
Eun-Suk Jang ◽  
Nam-Ho Lee ◽  
Sang-Sik Jang ◽  
Min Lee
Keyword(s):  
Absorption Coefficient ◽  
Ultrasonic Treatment ◽  
Sound Absorption ◽  
Gas Permeability ◽  
Treated Wood ◽  
Untreated Wood ◽  
Sound Absorption Coefficient ◽  
Permeability Constant ◽  
Average Value ◽  
Permeability Increase

AbstractWe investigated the effect of ultrasonic treatment on Malas (Homalium foetidum) gas permeability and sound absorption coefficient using the transfer function method. Results showed a longitudinal average Darcy permeability constant of 2.02 (standard deviation SD 0.72) for untreated wood and 6.15 (SD 3.07) for ultrasound-treated wood, a permeability increase of 3.04 times. We also determined the average sound absorption coefficients in the range of 50 to 6.4 kHz and NRC (noise reduction coefficient: average value of sound absorption coefficient value at 250, 500, 1000, and 2000 Hz) of untreated Malas. Those values were 0.23 (SD 0.02) and 0.13 (SD 0.01), respectively, while those of ultrasonic-treated Malas were 0.28 (SD 0.02) and 0.14 (SD 0.02), a 19.74% increase in average sound absorption coefficient.

Research of Possibilities of Using the Recycled Materials Based on Rubber and Textiles Combined with Vermiculite Material in the Area of ​​Noise Reduction

2014 ◽  
Vol 1001 ◽  
pp. 171-176 ◽  
Author(s):  
Pavol Liptai ◽  
Marek Moravec ◽  
Miroslav Badida
Keyword(s):  
Absorption Coefficient ◽  
Standing Wave ◽  
Sound Pressure Level ◽  
Sound Absorption ◽  
Sound Pressure ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Absorption Coefficient ◽  
Physical Parameters ◽  
Materials Research

This paper describes possibilities in the use of recycled rubber granules and textile materials combined with vermiculite panel. The aim of the research is the application of materials that will be absorbing or reflecting sound energy. This objective is based on fundamental physical principles of materials research and acoustics. Method of measurement of sound absorption coefficient is based on the principle of standing wave in the impedance tube. With a sound level meter is measured maximum and minimum sound pressure level of standing wave. From the maximum and minimum sound pressure level of standing wave is calculated sound absorption coefficient αn, which can take values from 0 to 1. Determination of the sound absorption coefficient has been set in 1/3 octave band and in the frequency range from 50 Hz to 2000 Hz. In conclusion are proposed possibilities of application of these materials in terms of their mechanical and physical parameters.

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