Quantification of the acoustic response of a material using an amplitude modulated wave train

Martínez, Uriel Victoria; Vázquez-Cerón, E. R.; Saldaña-Cantarey, D.; Villeda-Ayala, R.; Lancón-Rivera, L. A.; García-Martínez, S. G.; Arroyo-Pedroza, V.

doi:10.1080/10739149.2021.1983825

Cited by 2 publications

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References 6 publications

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“…La caracterización acústica de los compósitos se realizó en un tubo de impedancias de dos cámaras, las cuales tienen diámetro de 0.12 m y un largo de 8 m y están unidas por un cople donde se coloca la muestra, además que permite darle una continuación al tubo de impedancia. El sistema cuenta con cuatro micrófonos colocados a lo largo del tubo, tres de ellos en la primera cámara acústica y el cuarto micrófono se encuentra posicionado inmediatamente después del material de prueba, como se muestra en la Figura 20 [56]. El registro de la onda incidente y reflejada se realizó con el micrófono 2 y la onda transmitida con el micrófono 4.…”

Section: Caracterización Acústicaunclassified

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Estudio de compósitos de fibras naturales y arcilla para aplicaciones acústicas

Martínez¹

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During the last decade, actions and studies to counteract the effects of noise have increased through the use of insulating or absorbent materials, and civil regulations based on monitoring in urban areas, since exposure to high levels of sound pressure can cause psychological and physiological health problems such as anxiety, depression, stress, fatigue, cardiac, hearing or cognitive problems, as well as irreversible hearing loss. This work aims to develop and study natural compounds made of clay reinforced with coconut or nopal fibers to analyze their acoustic coefficients and determine their applications as insulation or conditioning material. The composites were obtained incorporating 25, 50 and 75% by weight of each fiber with bentonite clay. The physical and chemical characterization of the composites was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy, Fourier transforms infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The properties of hardness and apparent density of the composites were obtained from samples aged three months. Using XRD, the compounds were identified in the bentonite: montmorillonite, quartz and feldspar. The FT-IR allowed the identification of the functional groups of the clay and for the fibers the presence of lignin and hemicellulose was determined. Micrographs show that coconut fiber is more porous than nopal; the size of the nopal fibers was between 71.8 and 219.7 nm (electron microscopy) and that of the coconut fibers was 0.1613 mm (optical microscopy). The apparent density of the composites follows the model of the mixture rule, while the hardness changes very little in the samples prepared with nopal fiber. Through ATG it was found that bentonite improves the thermal stability of the composites. The acoustic absorption, reflection, and transmission coefficients of the materials were determined using the impedance tube method, in the range of 50 to 10,000 Hz. The samples obtained after the synthesis process was weighed and characterized in the impedance tube; For the humidity tests, a drop was placed on the surface of the sample and the characterization process was repeated. These tests were carried out until 4 drops of water were added to each composite. The results showed an increase in the acoustic absorption properties when adding the fibers in the composites, where it was observed that the coconut fiber presented a higher sound absorption than the nopal fiber. The hardness and density of the material are directly related to a reduction in the absorption coefficient, although the tests carried out show that the nopal fibers in the composites do not increase their hardness and their acoustic properties, unlike coconut fibers. The results obtained from the acoustic characterization carried out in the surface humidity test showed that the absorption, reflection and absorption coefficients of the coconut change with increasing humidity in the samples. While, in the case of nopal, due to its composition and hydrophobic properties, there is no significant variation in its acoustic properties. Composites made from coconut fiber have better acoustic absorption and reduction properties, while those made from nopal fiber stand out in terms of sound reflection.

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Section: Caracterización Acústicaunclassified

“…abarcando un rango de frecuencias hasta los 10 kHz. El análisis y procesamiento de las señales cuantificó los coeficientes acústicos de reflexión, transmisión y absorción, en el dominio de la frecuencia [57,56].…”

Section: Caracterización Acústicaunclassified

Estudio de compósitos de fibras naturales y arcilla para aplicaciones acústicas

Martínez¹

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Acoustic properties of composites materials based on bentonite and coconut or cactus (nopal) fibers

Martínez

Loera‐Serna

Vázquez-Cerón

2023

Journal of Composite Materials

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Materials made from natural fibers or waste have been studied to acquire a composite with good acoustical isolation properties, commercial materials used in this concern are polyurethane foam, fiberglass, Rockwool, and drywall. This work proposes using waste coconut and cactus ( Opuntia ficus-indica) fibers to synthesize bentonite composites and study their physicochemical and acoustic properties. Physicochemical properties of precursor and composites (75% wt. fiber) were determined by XRD, FTIR, N2 adsorption, optical, and SEM microscopies. The transmission, reflection, and absorption coefficients, 50 to 10,000 Hz, were obtained in an impedance tube and were compared with commercial materials. The composites were subjected to surface humidity and thermal (30, 50, and 70°C) tests to evaluate the stability of acoustic properties. The mechanical properties of the composites are improved with the addition of bentonite, hardness is increased by 6.7% and 0.9%, and the density is decreased by 73.6% and 45.5%, for coconut and nopal, respectively, porosity also changes. We corroborated the significant presence of montmorillonite in bentonite (XRD), while the nopal or coconut fibers are composed of hemicellulose, cellulose, and lignin (FTIR). Also, mucilage was identified in the nopal samples as adherent biopolymer that generates stability either thermally or in wetting conditions. Coconut fiber has a high absorption coefficient (similar to polyurethane), which is reduced with humidity. However, by adding bentonite, the reflection is more elevated, and transmission is lower than commercial materials. The bentonite and nopal (fiber and composite) presented stability in the acoustic coefficients as a function of humidity and temperature.

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Quantification of the acoustic response of a material using an amplitude modulated wave train

Cited by 2 publications

References 6 publications

Estudio de compósitos de fibras naturales y arcilla para aplicaciones acústicas

Estudio de compósitos de fibras naturales y arcilla para aplicaciones acústicas

Acoustic properties of composites materials based on bentonite and coconut or cactus (nopal) fibers

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