Proposal of numerical models to predict the diffuse field sound absorption of finite sized porous materials – BEM and FEM approaches

Pereira, Marco; Mareze, Paulo Henrique; Godinho, L.; Amado-Mendes, Paulo; Ramis, J.

doi:10.1016/j.apacoust.2021.108092

Cited by 20 publications

(6 citation statements)

References 36 publications

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“…Although the results of thermal conductivity coefficient were discrete, the values of the sound absorption coefficient at normal incidence achieved in this study indicated the potential of these fully bio-based composites as alternative materials for acoustic insulating panels. Further analyses to measure the sound absorption coefficient at diffuse incidence with large-area samples (10–12 m 2 ) in a reverberating chamber, according to ISO 354:2003, are needed to show the effect of refracted sound waves within the material volume [ 20 , 21 ].…”

Section: Resultsmentioning

confidence: 99%

Sustainable Sheep Wool/Soy Protein Biocomposites for Sound Absorption

Urdanpilleta

Leceta²,

Guerrero³

et al. 2022

Polymers

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The wool fibers of the Latxa sheep breed were combined with a soy protein isolate (SPI) matrix to develop sustainable biocomposites with acoustic properties, adding value to Latxa sheep wool, which is currently considered a residue. Samples with 7, 10, 15, and 20 wt % wool were prepared by freeze drying in order to develop porous structures, as shown by SEM analysis. Additionally, XRD analysis provided the evidence of a change toward a more amorphous structure with the incorporation of wool fibers due to the interactions between the soy protein and keratin present in wool fibers, as shown by the relative intensity changes in the FTIR bands. The biocomposites were analyzed in a Kundt’s tube to obtain their sound absorption coefficient at normal incidence. The results showed an acoustic absorption coefficient that well-surpassed 0.9 for frequencies above 1000 Hz. This performance is comparable to that of the conventional synthetic materials present in the market and, thus, sheep wool/SPI biocomposites are suitable to be used as acoustic absorbers in the building industry, highlighting the potential of replacing not only synthetic fibers but also synthetic polymers, with natural materials to enhance the sustainability of the building sector.

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Section: Resultsmentioning

confidence: 99%

Sustainable Sheep Wool/Soy Protein Biocomposites for Sound Absorption

Urdanpilleta

Leceta²,

Guerrero³

et al. 2022

Polymers

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“…Nevertheless, as it was shown in previous sections, the model simplicity only requires the absorption coefficient measured in an impedance tube, which can be calculated with ISO 10534 standard. Thus, the present work presents just two measures of the absorption coefficient, one for a porous absorber [37], and the other for PET fibers [38], later described in Sections 3.1 and 3.2.…”

Section: Methodsmentioning

confidence: 99%

“…Due to its absorptive capacity and flame-retardant ability, its use is extensive in building acoustics as an absorbing material. In Reference [37], material absorption results are presented for a 60 mm sheet, and so they are taken here as a reference for comparison with the NEAM model.…”

Section: Porous Melamine Foammentioning

confidence: 99%

Numerical Equivalent Acoustic Material for Air-Filled Porous Absorption Simulations in Finite Different Time Domain Methods: Design and Comparison

Iglesias,

Godinho,

Redondo

2024

Applied Sciences

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Extracting the microscopic parameters of a porous material is a complex task, and attempts have been made to develop models that can simulate their characteristics, gathering the least amount of information possible. As a case in point, tests to evaluate macroscopic behaviors such as tortuosity, which depends directly on the microscopic fluid velocities, are highly susceptible to generate errors if the precision of the measurement devices is not correct, and the same goes for the other parameters. For this reason, in this paper, a sound propagation model in porous materials with a rigid frame is presented based on a local theory, which tries to simplify, even more, the way to obtain the basic characteristics of porous materials, such as their absorption coefficient at normal and random incidence, and their normal surface impedance. The proposed linearized equivalent fluid model presents four phenomenological coefficients, which characterize acoustic propagation trough the material. Their values are obtained from the material thickness and a measurement in an impedance tube following the ISO 10534 standard. Thus, what is only required is the measured absorption coefficient, either on one third or one octave bands, to fully represent the acoustic behavior in the finite different in time domain (FDTD) method. The model has been simulated with FDTD in porous and fibrous kernels, and the results show a strong agreement with the laboratory measurements and with the analytical results calculated with well-established semi-phenomenological models.

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“…Laboratory tests can obtain the relevant mechanical properties of coal and rock objectively and accurately, but in order to explore the evolution mechanism of cracks, we need to use high-precision instruments, the test cost is high, and the experiment can not be repeated. In recent years, numerical simulation is often used in the study and analysis of fracture propagation in rock materials, such as Finite Element Method (FEM), Finite Difference Method (FDM), , Boundary Element Method (BEM), Cellular Automata (CA), , Discrete Element Method (DEM), , Universal Distinct Element Code (UDEC), Particle Flow Code(PFC), , Realistic Failure Process Analysis (RFPA), , etc. Particle Flow Code has become an important research method in mining and geotechnical engineering.…”

Section: Introductionmentioning

confidence: 99%

Failure Behavior and Fracture Evolution Mechanism of Coal with Fissures around Holes

Wang,

Zhang

2024

ACS Omega

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The fracture of coal is the main channel of gas flow and an important factor affecting the stability and efficiency of gas drainage boreholes. The coal structure, the development of hole cracks, and the degree of deformation are different. It affects the strength and mechanical deformation characteristics of coal to a great extent. In order to investigate the law of fracture evolution around the borehole of fractured coal, uniaxial and triaxial compression tests of raw coal samples have been carried out. The stress field evolution characteristics of fractured coal under compression were analyzed by Particle Flow Code (PFC 2D ). The strength, deformation, and fracture evolution behavior of fractured coal around boreholes under different confining pressures were studied. The results show that the compressive strength and fracture morphology evolution characteristics of coal around the hole are obviously related to the confining pressure and fracture occurrence of raw coal. The borehole structure itself has an important influence on the distribution location of the shear failure zone of the fracture around the hole, and its influence degree increases with the decrease of borehole confining pressure. During the deformation of coal with cracks around the hole, the initiation, propagation, and union behavior of cracks are related to the crack angle β. The cracks with β 0 and 180°are most easily closed during compression and the cracks with β 90°have little effect on the crack propagation zone. When the crack angle β is 45°, it is most easy to sprout and expand at the end; when the coal is compressed to the ultimate strength, the increase rate of the tensile crack increases, and the polymerization and combination behavior of the crack is more obvious. The evolution cloud map of the stress field can better reflect the evolution characteristics of fracture development, expansion, and fracture in the process of coal loading. Studying the failure behavior and fracture evolution mechanism of the coal around the hole can better predict and control the gas migration and extraction effect, which is of great significance to prevent the occurrence of gas accidents.

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Proposal of numerical models to predict the diffuse field sound absorption of finite sized porous materials – BEM and FEM approaches

Cited by 20 publications

References 36 publications

Sustainable Sheep Wool/Soy Protein Biocomposites for Sound Absorption

Sustainable Sheep Wool/Soy Protein Biocomposites for Sound Absorption

Numerical Equivalent Acoustic Material for Air-Filled Porous Absorption Simulations in Finite Different Time Domain Methods: Design and Comparison

Failure Behavior and Fracture Evolution Mechanism of Coal with Fissures around Holes

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