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COBEM 2019
25th International Congress of Mechanical Engineering
EVALUATION OF THE ACOUSTIC PROPERTIES WITH INVERSE CHARACTERIZATION WITH THIN NATURAL SAMPLE
Submission Author:
Nelson Legat Filho , PR
Co-Authors:
Nelson Legat Filho, Ana Carolina Mendonça Mansur, Key Fonseca de Lima, Nilson Barbieri, Fernando Jun Hattori Terashima, Jacqueline Terre de Souza
Presenter: Nelson Legat Filho
doi://10.26678/ABCM.COBEM2019.COB2019-1967
Abstract
As known, porous materials are good acoustical attenuators and widely used in acoustic filters. However, to determine the properties of these materials it is a complex process due to the non-homogenous structure. For the evaluation of the acoustical properties, it is required high precision equipment, in other words, high cost. In this paper, an alternative method using a software with an optimization algorithm, estimate with good agreement, some of these acoustical properties, such as flow resistivity, porosity, tortuosity, viscous and thermal length. The inverse method denoted by Johnson-Champoux-Allard (JCA) is applied within the optimization algorithm and compared with the experimental characterization (absorption coefficient and surface impedance of the material) using the impedance tube. The comparison in this work, between the JCA model and the experimental showed good convergence for the estimation of the five properties above of the common foam and coconut fiber.
Keywords
Porous materials, characterization, Genetic Algorithms, natural fibers, Acoustics, Vibrations
