1. |
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, 2022Streszczenie: 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. Słowa kluczowe: double porosity, additive manufacturing, sound absorption, pressure diffusion, multi-scale modelling Afiliacje autorów:
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) |
| | 100p. |
2. |
Venegas R.♦, Zieliński T.G., Núñez G.♦, Bécot F.-X.♦, Acoustics of porous composites,
COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2021.109006, Vol.220, pp.109006-1-14, 2021Streszczenie: Acoustic wave propagation in porous composites is investigated in this paper. The two-scale asymptotic homogenisation method is used to obtain the macroscopic description of sound propagation in such composites. The developed theory is both exemplified by introducing analytical models for the effective acoustical properties of porous composites with canonical inclusion patterns (i.e. a porous matrix with a periodic array of cylindrical or spherical inclusions) and validated by comparing the models predictions with the results of direct finite-element simulations and experimental testing, showing good agreement in all cases. It is concluded that the developed theory correctly captures the acoustic interaction between the constituents of the porous composite and elucidates the physical mechanisms underlying the dissipation of sound energy in such composites. These correspond to classical visco-thermal dissipation in the porous constituents, together with, for the case of composites made from constituents characterised by highly contrasted permeabilities, pressure diffusion which provides additional and tunable sound energy dissipation. In addition, this work determines the conditions for which a rigidly-backed porous composite layer can present improved sound absorption performance in comparison with that of layers made from their individual constituents. Hence, the presented results are expected to guide the rational design of porous composites with superior acoustic performance. Słowa kluczowe: porous composites, wave propagation, acoustical properties, homogenisation, pressure diffusion Afiliacje autorów:
Venegas R. | - | MATELYS – Research Lab (FR) | Zieliński T.G. | - | IPPT PAN | Núñez G. | - | inna afiliacja | Bécot F.-X. | - | MATELYS – Research Lab (FR) |
| | 200p. |
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Núñez G.♦, Venegas R.♦, Zieliński T.G., Bécot F.-X.♦, Equivalent fluid approach to modeling the acoustical properties of polydisperse heterogeneous porous composites,
PHYSICS OF FLUIDS, ISSN: 1070-6631, DOI: 10.1063/5.0054009, Vol.33, No.6, pp.062008-1-19, 2021Streszczenie: This paper investigates sound propagation in polydisperse heterogeneous porous composites. The two-scale asymptotic method of homogenization is used to obtain a macroscopic description of the propagation of sound in such composites. The upscaled equations demonstrate that the studied composites can be modeled as equivalent fluids with complex-valued frequency-dependent effective parameters (i.e., dynamic viscous permeability and compressibility) as well as unravel the sound energy dissipation mechanisms involved. The upscaled theory is both exemplified by introducing analytical and hybrid models for the acoustical properties of porous composites with different geometries and constituent materials (e.g., a porous matrix with much less permeable and/or impervious inclusions with simple or complex shapes) and validated through computational experiments successfully. It is concluded that the developed theory rigorously captures the physics of acoustic wave propagation in polydisperse heterogeneous porous composites and shows that the mechanisms that contribute to the dissipation of sound energy in the composite are classical visco-thermal dissipation together with multiple pressure diffusion phenomena in the heterogeneous inclusions. The results show that the combination of two or more permeable materials with highly contrasted permeabilities
can improve the acoustic absorption and transmission loss of the composite. This paper provides fundamental insights into the propagation of acoustic waves in complex composites that are expected to guide the rational design of novel acoustic materials. Afiliacje autorów:
Núñez G. | - | inna afiliacja | Venegas R. | - | MATELYS – Research Lab (FR) | Zieliński T.G. | - | IPPT PAN | Bécot F.-X. | - | MATELYS – Research Lab (FR) |
| | 100p. |