The Semi-Empirical and Empirical Models for Predicting Sound Absorption Coefficients for a Novel Porous Laminated Composite Material

2003 ◽  
Vol 9 (11) ◽  
pp. 1249-1263
Author(s):  
Tsung-Lung Yang ◽  
Rongshun Chen
Keyword(s):  
Composite Material ◽  
Absorption Coefficient ◽  
Empirical Model ◽  
Sound Absorption ◽  
Laminated Composite ◽  
Sound Absorption Coefficient ◽  
Numerical Predictions ◽  
Viscous Loss ◽  
Semi Empirical ◽  
Laminated Composite Material

Made of polymer, metal, and polymer fibers of low melting point, a porous laminated composite material (PLCM) exhibits very highly sound absorption coefficient over the frequency of 500-2000 Hz with a relatively thin structure. In this paper we present two models to predict sound absorption characteristics for a PLCM. Firstly, we derive a semi-empirical model in which the flow resistivity of the PLCM is a function of the fibrous surface area under the assumption that most energy loss is due to the viscous loss consumed in the fibrous surface of a PLCM. Secondly, we propose an empirical model to predict the characteristic impedance and the propagation constant, which then is employed to determine the sound absorption coefficient for a new PLCM. Numerical predictions have been performed and experiments have been conducted to validate the two proposed models.

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%.

Sound absorption of textile curtains – theoretical models and validations by experiments and simulations

2016 ◽  
Vol 88 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Reto Pieren ◽  
Beat Schäffer ◽  
Stefan Schoenwald ◽  
Kurt Eggenschwiler
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Planning Process ◽  
Measurement Data ◽  
Theoretical Models ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Semi Empirical ◽  
Field Sound ◽  
Good Agreement

Textile curtains can be designed to be good sound absorbers. Their acoustical performance, as usually described by the sound absorption coefficient, not only depends on the textile itself but also on the drapery fullness and the backing condition, that is, the spacing between the fabric and a rigid backing wall, or the absence of a backing in the case of a freely hanging curtain. This article reviews existing models to predict the diffuse-field sound absorption coefficient, which to date can only predict the case of flat curtains. A set of existing models is extended to the case of curtains with drapery fullness using a semi-empirical approach. The models consider different backing conditions, including freely hanging curtains. The existing and new models are validated by comparing predicted sound absorption coefficients with data measured in a reverberation room. Hereby, curtains consisting of different fabrics and with different degrees of fullness are considered. Besides situations with rigid backing, also the measurement data of textiles hung freely in space are included in this study. Comparisons reveal a very good agreement between measured and predicted sound absorption coefficients. Compared to currently available commercial sound absorption prediction software that can only handle the situation of flat textiles with rigid backing, the results of the presented models not only show a better agreement with measured data, but also cover a broader range of situations. The presented models are thus well applicable in the design and development of new textiles as well as in the room acoustical planning process.

scholarly journals Sound Absorption Performance of the Poplar Seed Fiber/PCL Composite Materials

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1465 ◽  
Author(s):  
Yingjie Liu ◽  
Lihua Lyu ◽  
Jing Guo ◽  
Ying Wang
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Fractal Dimensions ◽  
Sound Absorption Coefficient ◽  
Process Conditions ◽  
Pressing Method ◽  
Absorption Frequency ◽  
Absorption Performance

Composite materials were prepared by the hot pressing method using poplar seed fibers and polycaprolactone (PCL) as the raw materials to solve the problems related to the recycling of waste fibers. The effects of mass fraction of poplar seed fibers, the volume density, and thickness on the sound absorption performance of the resulting composite materials were studied. The sound absorption coefficient curves of the composite material were obtained by the acoustic impedance transfer function method. The sound absorption coefficient of the composite material that was prepared under the optimal process conditions was higher than 0.7, and the effective sound absorption frequency band was wide. According to the box counting dimension method, which is based on the fractal theory, the fractal dimensions of the composite materials were calculated while using the Matlab program. The relationships between the fractal dimensions and the volume densities, mass fractions of poplar seed fibers, and thicknesses of the composite materials were also analyzed. Subsequently, the quantitative relationship between the fractal dimension and the sound absorption property parameters of the composite material was established in order to provide a theoretical basis for the design of the sound absorption composite material.

An Experimental and Simulation Studies on Sound Absorption Coefficients of Banana Fibers and their Reinforced Composites

2016 ◽  
Vol 12 ◽  
pp. 9-20 ◽  
Author(s):  
Muhammad Khusairy bin Bakri ◽  
Elammaran Jayamani ◽  
Soon Kok Heng ◽  
Sinin Hamdan ◽  
Akshay Kakar
Keyword(s):  
Absorption Coefficient ◽  
Empirical Model ◽  
Sound Absorption ◽  
Epoxy Composites ◽  
Sound Absorption Coefficient ◽  
Simulation Studies ◽  
Reinforced Composites ◽  
Banana Fiber ◽  
Banana Fibers ◽  
Flow Resistivity

This research focuses on the simulation of sound absorption coefficient of banana fiber and experimentation of sound absorption coefficient of banana fiber epoxy composites. For simulation, ‘Mechel’ empirical model was used to manipulate the flow resistivity and ‘Delany and Bazley’ empirical model was used to develop the prediction of sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. For experimentation, two-microphone transfer function impedance tube model was used to analyze the sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. Based on simulation, it is predicted and analyzed that the sound absorption coefficient of banana fiber found to be as high as 0.97 for the effects on the material thickness of banana fiber and 0.64 for the effects on the fiber diameter size and flow resistivity of banana fiber in the frequency ranges from 500 Hz to 6000 Hz. According to experimental results, it is observed and analyzed that the sound absorption coefficient of banana epoxy composites found to be as high as 0.11 for untreated banana epoxy composites and 0.12 for treated banana epoxy composites in the frequency ranges from 500 Hz to 6000 Hz.

scholarly journals Sound-Absorption Performance and Fractal Dimension Feature of Kapok Fibre/Polycaprolactone Composites

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1000 ◽  
Author(s):  
Lihua Lyu ◽  
Duoduo Zhang ◽  
Yuanyuan Tian ◽  
Xinghai Zhou
Keyword(s):  
Composite Material ◽  
Fractal Dimension ◽  
Absorption Coefficient ◽  
Mass Fraction ◽  
Sound Absorption ◽  
Volume Density ◽  
Sound Absorption Coefficient ◽  
Pressing Method ◽  
Absorption Frequency ◽  
Absorption Performance

This article introduces a kind of composite material made of kapok fibre and polycaprolactone by the hot-pressing method. The effects of volume density, mass fraction of kapok fibre, and thickness on the sound-absorption performance of composites were researched using a single-factor experiment. The sound-absorption performance of the composites was investigated by the transfer function method. Under the optimal process parameters, when the density of the composite material was 0.172 g/cm3, the mass fraction of kapok was 40%, and the thickness was 2 cm, the composite material reached the maximum sound-absorption coefficient of 0.830, and when the sound-absorption frequency was 6300 Hz, the average sound-absorption coefficient was 0.520, and the sound-absorption band was wide. This research used the box dimension method to calculate composites’ fractal dimensions by using the Matlab program based on the fractal theory. It analysed the relationships between fractal dimension and volume density, fractal dimension and mass fraction of kapok fibre, and fractal dimension and thickness. The quantitative relations between fractal dimension and maximum sound-absorption coefficient, fractal dimension, and resonant sound-absorption frequency were derived, which provided a theoretical basis for studying sound-absorption performance. The results showed that kapok fibre/polycaprolactone composites had strong fractal characteristics, which had important guiding significance for the sound-absorption performance of kapok fibre composites.

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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