The acoustic properties of recycled polyurethane foams are well known. Such foams are used as a part of acoustic solutions in different fields such as building or transport. This paper aims to seek improvements in the sound absorption of these recycled foams when they are combined with fabrics. For this aim, foams have been drilled with cylindrical perforations, and also combined with different fabrics. The effect on the sound absorption is evaluated based on the following key parameters: perforation rate (5% and 20%), aperture size (4 mm and 6 mm), and a complete perforation depth. Experimental measurements were performed by using an impedance tube for the characterization of its acoustic behavior. Sound absorption of perforated samples is also studied—numerically by finite element simulations, where the viscothermal losses were considered; and analytically by using models for the perforated foam and the fabric. Two textile fabrics were used in combination with perforated polyurethane samples. Results evidence a modification of the sound absorption at mid frequencies employing fabrics that have a membrane-type acoustic response.
A fibrous material is characterized by its fineness, flexibility and high length/fineness ratio and it is used to reduce noise in indoor rooms due to their porous structure. The aim of this work is focused on investigating the structure of two different fibers (acrylic and polyester) from the analysis of the macrostructural parameters, such as fineness, length and cross-section (solid or hollow). Furthermore, the degree of influence of these parameters on the average sound absorption has been investigated. The sound absorption coefficient of fibers is measured at normal incidence in the impedance tube. In acrylic fibers, results showed that the fineness of the fiber has a significant influence on the sound absorption compared to the length of the fiber. In polyester fibers, hollow fibers have a better acoustic behavior compared to solid fibers.
<p>En este trabajo se desarrollan de forma numérica modelos empíricos que permiten conocer el comportamiento acústico de materiales utilizados en soluciones constructivas en la edificación. Este trabajo se engloba dentro del Máster Universitario en Ingeniería Acústica (MIA) de la Escuela Politécnica Superior de Gandía en la Universitat Politècnica de València. El ingeniero acústico, para conseguir todas las competencias que se exigen en la titulación, necesita conocer el comportamiento acústico de materiales, o soluciones acústicas, así como también necesita desarrollar herramientas de simulación numérica. Se propone, en este estudio, una evaluación numérica de modelos empíricos que permita al alumnado combinar competencias de asignaturas diferentes para alcanzar un objetivo común, ofreciendo así al alumnado herramientas multidisciplinares que debe utilizar en su incorporación al mundo laboral.</p>
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