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Zielinski T.G., Dauchez N.♦, Boutin T.♦, Leturia M.♦, Wilkinson A.♦, Chevillotte F.♦, Bécot F.-X.♦, Venegas R.♦, Taking advantage of a 3D printing imperfection in the development of sound-absorbing materials,
APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2022.108941, Vol.197, pp.108941-1-22, 2022Abstract: At first glance, it seems that modern, inexpensive additive manufacturing (AM) technologies can be used to produce innovative, efficient acoustic materials with tailored pore morphology. However, on closer inspection, it becomes rather obvious that for now this is only possible for specific solutions, such as relatively thin, but narrow-band sound absorbers. This is mainly due to the relatively poor resolutions available in low-cost AM technologies and devices, which prevents the 3D-printing of pore networks with characteristic dimensions comparable to those found in conventional broadband sound-absorbing materials. Other drawbacks relate to a number of imperfections associated with AM technologies, including porosity or rather microporosity inherent in some of them. This paper shows how the limitations mentioned above can be alleviated by 3D-printing double-porosity structures, where the main pore network can be designed and optimised, while the properties of the intentionally microporous skeleton provide the desired permeability contrast, leading to additional broadband sound energy dissipation due to pressure diffusion. The beneficial effect of additively manufactured double porosity and the phenomena associated with it are rigorously demonstrated and validated in this work, both experimentally and through precise multi-scale modelling, on a comprehensive example that can serve as benchmark. Keywords: double porosity, additive manufacturing, sound absorption, pressure diffusion, multi-scale modelling Affiliations:
Zielinski T.G. | - | IPPT PAN | Dauchez N. | - | Sorbonne University Alliance (FR) | Boutin T. | - | Sorbonne University Alliance (FR) | Leturia M. | - | Sorbonne University Alliance (FR) | Wilkinson A. | - | Sorbonne University Alliance (FR) | Chevillotte F. | - | MATELYS – Research Lab (FR) | Bécot F.-X. | - | MATELYS – Research Lab (FR) | Venegas R. | - | MATELYS – Research Lab (FR) |
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Zieliński T.G., Venegas R.♦, Perrot C.♦, Červenka M.♦, Chevillotte F.♦, Attenborough K.♦, Benchmarks for microstructure-based modelling of sound absorbing rigid-frame porous media,
JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2020.115441, Vol.483, pp.115441-1-38, 2020Abstract: This work presents benchmark examples related to the modelling of sound absorbing porous media with rigid frame based on the periodic geometry of their microstructures. To this end, rigorous mathematical derivations are recalled to provide all necessary equations, useful relations, and formulae for the so-called direct multi-scale computations, as well as for the hybrid multi-scale calculations based on the numerically determined transport parameters of porous materials. The results of such direct and hybrid multi-scale calculations are not only cross verified, but also confirmed by direct numerical simulations based on the linearised Navier-Stokes-Fourier equations. In addition, relevant theoretical and numerical issues are discussed, and some practical hints are given. Keywords: porous media, periodic microstructure, wave propagation, sound absorption Affiliations:
Zieliński T.G. | - | IPPT PAN | Venegas R. | - | MATELYS – Research Lab (FR) | Perrot C. | - | other affiliation | Červenka M. | - | Czech Technical University in Prague (CZ) | Chevillotte F. | - | MATELYS – Research Lab (FR) | Attenborough K. | - | The Open University (GB) |
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Zieliński T.G., Chevillotte F.♦, Deckers E.♦, Sound absorption of plates with micro-slits backed with air cavities: analytical estimations, numerical calculations and experimental validations,
APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2018.11.026, Vol.146, pp.261-279, 2019Abstract: This work discusses many practical and some theoretical aspects concerning modelling and design of plates with micro-slits, involving multi-scale calculations based on microstructure. To this end, useful mathematical reductions are demonstrated, and numerical computations are compared with possible analytical estimations. The numerical and analytical approaches are used to calculate the transport parameters for complex micro-perforated (micro-slotted) plates, which allow to determine the effective properties of the equivalent fluid, so that at the macro-scale level the plate can be treated as a specific layer of acoustic fluid. In that way, the sound absorption of micro-slotted plates backed with air cavities can be determined by solving a multi-layer system of Helmholtz equations. Two such examples are presented in the paper and validated experimentally. The first plate has narrow slits precisely cut out using a traditional technique, while the second plate - with an original micro-perforated pattern - is 3D-printed. Keywords: micro-slotted plates, micro-perforated plates, sound absorption, microstructure-based modelling, 3D-printing Affiliations:
Zieliński T.G. | - | IPPT PAN | Chevillotte F. | - | MATELYS – Research Lab (FR) | Deckers E. | - | Katholieke Universiteit Leuven (BE) |
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