Permeability Measurement of Orthotropic Fibers Under an Acoustic Force Field

2009 ◽  
Author(s):  
Sanjay Sharma ◽  
Dennis Siginer
Keyword(s):  
Absorption Coefficient ◽  
Physical Properties ◽  
Force Field ◽  
Porous Materials ◽  
Acoustic Method ◽  
Orthotropic Medium ◽  
Frequency Range ◽  
Permeability Measurement ◽  
Acoustical Properties ◽  
Transverse Permeability

Using the validated acoustic method of determining physical properties of porous materials, acoustical properties of the orthotropic medium is used to predict longitudinal and transverse permeability. Measurement of samples in the impedance tube is conducted using ASTM E 1050 for a frequency range of 50 Hz to 6.4 KHz. The acoustical method is shown to compute longitudinal and transverse permeability for various porosity levels. The method describes permeability prediction for carbon, glass and hybrid lay ups. Longitudinal permeability calculated from the absorption coefficient of sized and unsized fibers is found to be the same in contrast to the flow methods.

Determination of Physical Properties of Isotropic Porous Materials by Impedance Tube

2009 ◽  
Author(s):  
Sanjay Sharma ◽  
Dennis Siginer
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Physical Properties ◽  
Porous Materials ◽  
Low Frequency ◽  
Permeability Measurement ◽  
Impedance Tube ◽  
Acoustical Properties ◽  
Acoustical Method

Simulation of fluid flow in porous materials depends upon the accuracy of permeability measurement. This study details the development of an acoustical method to determine permeability of porous medium. Standardized acoustical testing for low frequency using impedance tube is carried out to determine the acoustical properties of the fibers. Physical properties of porous medium are determined by reverse calculation from the acoustical properties. The acoustical method is validated by comparing the measured acoustical properties of the porous medium by the analytical method. A variety of foams and fibers are tested using this methodology.

Advanced Procedure Used for Determining the Absorption Coefficient of Sonic-Absorbent Materials

2011 ◽  
Author(s):  
Petru A. Pop ◽  
Patricia A. Ungur ◽  
Liviu Lazar ◽  
Florin M. Marcu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Indoor Environmental Quality ◽  
Sound Waves ◽  
Frequency Range ◽  
Entire Frequency Range ◽  
Acoustical Properties ◽  
Standing Wave Method ◽  
Gypsum Plaster ◽  
The Impact

Solving the acoustical problem and improving the impact indoor environmental quality represents a priority for many researchers and manufacturers of materials with a high noise reduction of coefficient rating. The paper presents a real solution for determination the sound-absorption coefficient of materials with acoustical properties from the gypsum family. The procedure used for test is standing wave method into a Kundt tube. The experiment setup used a complex installation of a Kundt tube containing a loudspeaker for emitting the sound waves at a well-defined frequency by a first PC, a microphone for detecting and transmitting the signal to a second PC for analyzing and processing the data. All of these were performed by using MATLAB Programs. Tests were conducted with two material samples with original receipts, one from gypsum and other from special gypsum plaster with sound-absorbent properties. The frequency was set separately for each material from 50 Hz to 1250 Hz to determine their sound-absorption coefficients. The result of experiments shows the efficiency of installation and superiority of special gypsum plaster vs. gypsum along entire frequency range of testing that can be carrying on to other materials with sound properties.

On the Absorption Coefficient of Porous Corrugated Surfaces

2002 ◽  
Vol 124 (3) ◽  
pp. 329-333 ◽  
Author(s):  
Francisco Simo´n ◽  
Rosa M. Rodrı´guez ◽  
Jaime Pfretzschner
Keyword(s):  
Experimental Data ◽  
Reflection Coefficient ◽  
Absorption Coefficient ◽  
Porous Materials ◽  
Analytical Approximation ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Corrugated Surfaces ◽  
Theoretical Results

A classical way of improving acoustical absorption performances of porous materials is the use of corrugated surfaces; this use can obtain lower cut-off frequencies and also improve the overall absorption over a wide frequency range. An analytical approximation is presented for the calculus of the absorption on this kind of surfaces, where the thickness gradient is represented as a series of steps. Reflection coefficient of every step is obtained and will contribute to the net reflection coefficient. Theoretical results will be presented and shown to agree with experimental data.

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 Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

Research of the Wood’s Alloy Crystallization Process Using the Acoustic Method

2021 ◽  
Vol 410 ◽  
pp. 855-861
Author(s):  
Aleksandr Yu. Yaroslavkin ◽  
Eugene A. Tyurin ◽  
Darya A. Melnikova
Keyword(s):  
Speed Of Sound ◽  
Crystallization Process ◽  
Ultrasonic Method ◽  
Single Pulse ◽  
Acoustic Method ◽  
The State ◽  
Sound Signal ◽  
Frequency Range ◽  
Wood’S Alloy

The article examines the process of crystallization of Wood alloy using the ultrasonic method. The dependence of the determination of the speed of sound in three aggregate states of the alloy (liquid, solid, transition (liquid-solid)) was derived. The relation-ship with the amplitude values of the sound signal, a single pulse in determining the speed of sound, as well as in determining the state of the alloy is carried out. The data obtained allow us to analyze the state of the alloy and the measurement time and the specified frequency range directly in the process of crystallization.

scholarly journals Study on the sound absorption behavior of multi-component polyester nonwovens: experimental and numerical methods

2018 ◽  
Vol 89 (16) ◽  
pp. 3342-3361 ◽  
Author(s):  
Tao Yang ◽  
Ferina Saati ◽  
Kirill V Horoshenkov ◽  
Xiaoman Xiong ◽  
Kai Yang ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Absorption Coefficient ◽  
Empirical Model ◽  
Surface Impedance ◽  
Sound Absorption ◽  
Low Frequency ◽  
Accurate Method ◽  
Small Error ◽  
Sound Absorption Coefficient ◽  
Acoustical Properties

This study presents an investigation of the acoustical properties of multi-component polyester nonwovens with experimental and numerical methods. Fifteen types of nonwoven samples made with staple, hollow and bi-component polyester fibers were chosen to carry out this study. The AFD300 AcoustiFlow device was employed to measure airflow resistivity. Several models were grouped in theoretical and empirical model categories and used to predict the airflow resistivity. A simple empirical model based on fiber diameter and fabric bulk density was obtained through the power-fitting method. The difference between measured and predicted airflow resistivity was analyzed. The surface impedance and sound absorption coefficient were determined by using a 45 mm Materiacustica impedance tube. Some widely used impedance models were used to predict the acoustical properties. A comparison between measured and predicted values was carried out to determine the most accurate model for multi-component polyester nonwovens. The results show that one of the Tarnow model provides the closest prediction to the measured value, with an error of 12%. The proposed power-fitted empirical model exhibits a very small error of 6.8%. It is shown that the Delany–Bazley and Miki models can accurately predict surface impedance of multi-component polyester nonwovens, but the Komatsu model is less accurate, especially at the low-frequency range. The results indicate that the Miki model is the most accurate method to predict the sound absorption coefficient, with a mean error of 8.39%.

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