A New Empirical Model for Predicting the Sound Absorption of Polyfelt Fibrous Materials for Acoustical Applications

A New Empirical Model for Predicting the Sound Absorption of Polyfelt Fibrous Materials for Acoustical Applications Article example
Ph.D.
Article
Engineering and Construction
Pages 4 (1004 words)
Download 0
A New Empirical Model for Predicting the Sound Absorption of Polyfelt Fibrous Materials for Acoustical Applications I. Introduction Accurate modeling of the acoustical properties of porous materials is of considerable interest to acoustic and noise engineers and material manufacturers…

Introduction

Empirical models do not require detailed knowledge of the internal structure of the material nor are they derived from theoretical considerations. Delany and Bazley [1] showed that the values of the characteristic acoustic impedance and propagation coefficient for a range of fibrous materials, normalized as a function of frequency divided by flow resistivity could be presented as simple power law functions. Model for Impedance The model is based on numerous impedance tube measurements and is good for determining the bulk acoustic properties at frequencies higher than 250 Hz, but not at low frequencies [2,3]. The validity of this model for lower and higher frequencies was further extended by Bies and Hansen [4].Dunn and Davern [5] calculated new regression coefficients between characteristic acoustic impedance and propagation coefficient for low airflow resistivity values of polyurethane foams and multilayer absorbers. ...
Download paper
Not exactly what you need?

Related papers

Acoustical Characterization of porous Materials for Automotive Applications
Porous materials come in several forms, ranging from rigid to limp to elastic. They also vary across sound propagation parameters, such as porosity, tortuosity, flow, resistivity, viscous characteristic length and thermal characteristic length. Porous materials have two phases; the solid phase, which is fibrous in nature, forms the frame, while the interstitial fluid fills up the pores in the…
Characterisation material physical properties of porous materials
According to this theory, three different kinds of waves propagate within the porous material. One is the compression wave propagating in the fluid phase, the second is the compression wave travelling in the solid phase, and the third is the shear wave propagating in the solid phase (Pan & Jackson). The Biot model for predicting sound propagation in porous materials is based on five material…
Characterization models of poroelastic materials: A review
This paper reviews several characterization models of poroelastic materials. Both theoretical and numerical models such as empirical, phenomenological, finite element models, etc. are discussed. The aim is to provide a brief description and review of the various characterization models presently in existence. 3.2 Theoretical Modeling The determination of the sound absorption properties may be…
Materials and Hardware
The Change from One Material to Another in Aircraft Development The method for the choice of materials for aircraft development has changed over the years. For the Flyer, the Wright brothers utilized the first cast aluminium engine block and the major drivers for the material chosen were static strength and weight. The materials used on the main airframe were wood covered with a fabric. Wood is a…
Thermodynamics Applications
Use of fuels in London: The energy uses in the city of London in the residential, commercial, industrial and transportation sectors can be presented through the following chart based on data for the year 1998. The figure indicates the percentage use of the available energy sources in the city of London in different sectors. It can be observed that the transportation sector has the highest record…
Acoustical Characterization of Porous Materials for Automotive Application
There exists diversity when it comes to porous materials either artificial or natural. Sintered, steel wool, perforated materials and fiber metal are among the porous materials that have been increasingly used in automotive noise control. Following the diversity and variety of porous material characteristics, the study of porous media has proved to be wide and interesting. The review begins with…
Properties of Materials
According to a survey that was carried out by our firm, we realized that many instances windows were severely damaged. Upon keenly studying the damages, it was realized that it was partly due to environmental factors and partly due to poor maintenance. The damages on the widows caused variations in geometric configuration, composition, porosity and adherence of corrosion products. They also cause…