scholarly journals Graded and Anisotropic Porous Materials for Broadband and Angular Maximal Acoustic Absorption

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4605
Author(s):  
Théo Cavalieri ◽  
Jean Boulvert ◽  
Gwénaël Gabard ◽  
Vicent Romero-García ◽  
Marie Escouflaire ◽  
...  
Keyword(s):  
Porous Materials ◽  
Sound Absorption ◽  
Effective Properties ◽  
Numerical Study ◽  
Optimization Technique ◽  
Single Frequency ◽  
Acoustic Absorption ◽  
Graded Material ◽  
Manufacturing Techniques ◽  
Designed Materials

The design of graded and anisotropic materials has been of significant interest, especially for sound absorption purposes. Together with the rise of additive manufacturing techniques, new possibilities are emerging from engineered porous micro-structures. In this work, we present a theoretical and numerical study of graded and anisotropic porous materials, for optimal broadband and angular absorption. Through a parametric study, the effective acoustic and geometric parameters of homogenized anisotropic unit cells constitute a database in which the optimal anisotropic and graded material will be searched for. We develop an optimization technique based on the simplex method that is relying on this database. The concepts of average absorption and diffuse field absorption coefficients are introduced and used to maximize angular acoustic absorption. Numerical results present the optimized absorption of the designed anisotropic and graded porous materials for different acoustic targets. The designed materials have anisotropic and graded effective properties, which enhance its sound absorption capabilities. While the anisotropy largely enhances the diffuse field absorbing when optimized at a single frequency, graded properties appear to be crucial for optimal broadband diffuse field absorption.

scholarly journals Thermoelastic analysis of FGM hollow cylinder for variable parameters and temperature distributions using FEM

2020 ◽  
Vol 9 (1) ◽  
pp. 256-264
Author(s):  
Dinkar Sharma ◽  
Ramandeep Kaur
Keyword(s):  
Stress Field ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Functionally Graded ◽  
Gradient Index ◽  
Variable Parameters ◽  
Graded Material ◽  
Governing Differential Equation

AbstractThis paper presents, numerical study of stress field in functionally graded material (FGM) hollow cylinder by using finite element method (FEM). The FGM cylinder is subjected to internal pressure and uniform heat generation. Thermoelastic material properties of FGM cylinder are assumed to vary along radius of cylinder as an exponential function of radius. The governing differential equation is solved numerically by FEM for isotropic and anistropic hollow cylinder. Additionally, the effect of material gradient index (β) on normalized radial stresses, normalized circumferential stress and normalized axial stress are evaluated and shown graphically. The behaviour of stress versus normalized radius of cylinder is plotted for different values of Poisson’s ratio and temperature. The graphical results shown that stress field in FGM cylinder is influenced by some of above mentioned parameters.

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.

Biodegradable Acoustic Proficiency in Sound Absorption Capacity After Water Treatment and Testing by Impendence Tube Method

2021 ◽  
pp. 75-90
Author(s):  
Tushar Kanta Mohapatra ◽  
Suchismita Satapathy ◽  
Isham Panigrahi ◽  
Debesh Mishra
Keyword(s):  
Composite Material ◽  
Sound Absorption ◽  
Research Work ◽  
Absorption Capacity ◽  
Sound Insulation ◽  
Biodegradable Materials ◽  
Acoustic Absorption ◽  
Fiber Reinforced Composite ◽  
New Class ◽  
Reinforced Composite

The present research investigation aims to fabricate a new class of fiber reinforced composite material by using biodegradable materials with epoxy as the strengthening agent. In order to explore the possibilities of using the new class of composite material in required application areas, the research work is carried out mainly in the field of the acoustic absorption properties of these bio fibers as an alternate building material. Also, the utilization of these materials as sound insulation will also provide a good solution to the waste management.

The effect of the combination of multiple woven fabric and nonwoven on acoustic absorption

2019 ◽  
pp. 152808371985877 ◽  
Author(s):  
Pilar Segura-Alcaraz ◽  
Jorge Segura-Alcaraz ◽  
Ignacio Montava ◽  
Marilés Bonet-Aracil
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Woven Fabric ◽  
Sound Absorption Coefficient ◽  
Acoustic Absorption ◽  
Experimental Conditions ◽  
Resistive Layer ◽  
Textile Materials ◽  
Acoustic Absorption Coefficient ◽  
Fabric Structures

Textile materials can be used as acoustic materials. In this study, the acoustic absorption coefficient of multilayer fabrics with 60 ends/cm and 15, 30, 45, and 60 picks/cm is measured when the fabric is added as a resistive layer on top of a polyester nonwoven, in order to study the influence of the fabric spatial structure in the acoustic absorption of the assembly. Five different fabric structures are used. Design of experiments and data analysis tools are used to describe the influence of two manufacturing factors on the sound absorption coefficient of the ensemble. These factors are the fabric weft count (picks/cm) and the thickness of the nonwoven (mm). The experimental conditions under which the maximum sound absorption coefficient is achieved are found. The influence of each factor and a mathematical model are obtained. Results of statistical and optimization analysis show that for the same fabric density, sound absorption coefficient increases as the number of layers decreases.

Sound Absorption Optimization of Porous Materials Using BP Neural Network and Genetic Algorithm

2016 ◽  
Author(s):  
Lianhui Wang ◽  
Shuming Chen ◽  
Dengfeng Wang ◽  
Yang Jiang ◽  
Jing Chen
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Porous Materials ◽  
Bp Neural Network ◽  
Sound Absorption

Coating Composition Evolution during the Deposition of Al and N from Plasma on a Cylindrical Substrate

2016 ◽  
Vol 685 ◽  
pp. 690-694 ◽  
Author(s):  
Sergey A. Shanin ◽  
Anna G. Knyazeva ◽  
Olga Kryukova
Keyword(s):  
Chemical Reactions ◽  
Effective Properties ◽  
Cylindrical Specimen ◽  
Numerical Study ◽  
Coupling Model ◽  
Transfer Processes ◽  
Coating Composition ◽  
Transient Zone ◽  
Transfer Mechanisms

This paper presents the results of the numerical study of the coating composition evolution deposited on a cylindrical specimen from plasma containing aluminum and nitrogen. Calculations were based on a coupling model, which accounted for various transfer mechanisms and staged chemical reactions in the coating and in the transient zone. The evolution of the coating composition is connected with transfer processes, chemical reactions, and with the change of effective properties.

Porous materials for sound absorption

2018 ◽  
Vol 10 ◽  
pp. 25-35 ◽  
Author(s):  
Leitao Cao ◽  
Qiuxia Fu ◽  
Yang Si ◽  
Bin Ding ◽  
Jianyong Yu
Keyword(s):  
Porous Materials ◽  
Sound Absorption
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