Experimental Validation of an Acoustical Micro-Macro Model for Random Hollow Fibre Structures
This work investigates the validity of recent micro-macro solid fibre relationships for the case of a nonwoven fibre structure made from milkweed floss, a natural hollow fibre. The hypothesis that hollowness of the fibre has only small effects on the acoustics of the material is verified. This is done to ensure that the use of a single porosity model is justified. Therefore, the micro-macro solid fibre relationships are used to retrieve the macroscopic transport and acoustic properties of the fibrous material by the only knowledge of four measured microstructural features: porosity, effective inner and outer radii of the hollow fibre, and fibre orientation. Sound absorption coefficient predicted by two rigid-frame porous models are compared with standing wave tube measurements. The two rigid-frame porous models are the six-parameter Johnson-Lafarge model and the one-parameter Miki model. The parameters of these models are obtained by the micro-macro solid fibre relationships. The fibres of the tested nonwoven materials are mainly arranged randomly in parallel planes (i.e., layered fibrous media showing transverse isotropy). The predictions obtained by both rigid-frame porous models agree with experimental data when the acoustic excitation is normal to the layered fibrous media as well as when excitation is perpendicular.
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Document Type: Research Article
Publication date: January 1, 2019
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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