Zero-phase propagation in realistic plate-type acoustic metamaterials

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Zero-phase propagation in realistic plate-type acoustic metamaterials

[EN] We theoretically, numerically, and experimentally analyze the Density-Near-Zero (DNZ) regime of a one-dimensional acoustic metamaterial. This acoustic metamaterial is composed of thin elastic plates periodically clamped in an air-filled waveguide, and the effective dynamic zero mass density is obtained from the strong dispersion around the bandgaps associated with the resonances of the plates. We emphasize the importance of the impedance mismatch between the acoustic metamaterial and the surrounding waveguide at the frequency of the zero effective density in addition to the consequences of the inherent losses. As a result, the frequency of the zero phase propagation, i.e., the acoustic propagation with zero phase delay, is not exactly the frequency of the zero density and lies in the frequency bandgap where the effective density is negative. Considering these limitations, the zero phase propagation is still experimentally observed and a subwavelength acoustic dipole is numerically designed, thus demonstrating the possible realistic implementations of DNZ acoustic metamaterials.This article is based upon work from COST Action DENORMS CA15125, supported by COST (European Cooperation in Science and Technology). This work was funded by the Metaroom Project No. ANR-18-CE08-0021 and co-funded by ANR and RCG. J. Christensen acknowledges the support from the MINECO through a Ramon y Cajal grant (Grant No. RYC-2015-17156). J. Sanchez-Dehesa acknowledges the support from the Ministerio de Economia y Competitividad of the Spanish government and the European Union Fondo Europeo de Desarrollo Regional (FEDER) through Project No. TEC2014-53088-C3-1-R.Malléjac, M.; Merkel, A.; Sánchez-Dehesa Moreno-Cid, J.; Christensen, J.; Tournat, V.; Groby, J.; Romero García, V. (2019). Zero-phase propagation in realistic plate-type acoustic metamaterials. Applied Physics Letters. 115(13):134101-1-134101-5. https://doi.org/10.1063/1.5121295S134101-1134101-511513Graciá-Salgado, R., García-Chocano, V. M., Torrent, D., & Sánchez-Dehesa, J. (2013). Negative mass density andρ-near-zero quasi-two-dimensional metamaterials: Design and applications. Physical Review B, 88(22). doi:10.1103/physrevb.88.224305Huang, T.-Y., Shen, C., & Jing, Y. (2016). Membrane- and plate-type acoustic metamaterials. The Journal of the Acoustical Society of America, 139(6), 3240-3250. doi:10.1121/1.4950751Ma, G., Yang, M., Xiao, S., Yang, Z., & Sheng, P. (2014). Acoustic metasurface with hybrid resonances. Nature Materials, 13(9), 873-878. doi:10.1038/nmat3994Romero-García, V., Theocharis, G., Richoux, O., Merkel, A., Tournat, V., & Pagneux, V. (2016). Perfect and broadband acoustic absorption by critically coupled sub-wavelength resonators. Scientific Reports, 6(1). doi:10.1038/srep19519Stinson, M. R. (1991). The propagation of plane sound waves in narrow and wide circular tubes, and generalization to uniform tubes of arbitrary cross‐sectional shape. The Journal of the Acoustical Society of America, 89(2), 550-558. doi:10.1121/1.400379Niskanen, M., Groby, J.-P., Duclos, A., Dazel, O., Le Roux, J. C., Poulain, N., … Lähivaara, T. (2017). Deterministic and statistical characterization of rigid frame porous materials from impedance tube measurements. The Journal of the Acoustical Society of America, 142(4), 2407-2418. doi:10.1121/1.5008742Groby, J.-P., Lauriks, W., & Vigran, T. E. (2010). Total absorption peak by use of a rigid frame porous layer backed by a rigid multi-irregularities grating. The Journal of the Acoustical Society of America, 127(5), 2865-2874. doi:10.1121/1.3337235Allard, J. F., & Atalla, N. (2009). Propagation of Sound in Porous Media. doi:10.1002/9780470747339De Ryck, L., Groby, J.-P., Leclaire, P., Lauriks, W., Wirgin, A., Fellah, Z. E. A., & Depollier, C. (2007). Acoustic wave propagation in a macroscopically inhomogeneous porous medium saturated by a fluid. Applied Physics Letters, 90(18), 181901. doi:10.1063/1.243157

Experimental evidence of a hiding zone in a density-near-zero acoustic metamaterial

[EN] This paper examines the feasibility of cloaking an obstacle using Plate-type Acoustic Metamaterials (PAMs). We present two distinct strategies to cloak this obstacle, using either the near-zero-density regime of a periodic arrangement of plates or the acoustic doping phenomenon to achieve simultaneous zero-phase propagation and impedance matching. The strong limitations induced by viscothermal and viscoelastic losses that cannot be avoided in such a system are studied. A hiding zone is reported analytically, numerically, and experimentally. In contrast to cloaking, where zero-phase propagation must be accompanied by total transmission and zero reflection, the hiding configuration requires that the scattering properties of the hiding device must not be affected by the presence of the obstacle embedded in it. Contrary to cloaking, the hiding phenomenon is achievable even with a realistic PAM possessing unavoidable losses.This article is based upon the work from COST Action DENORMS (No. CA15125), supported by COST (European Cooperation). The authors would like to thank the support of the ANR-RGC METARoom (No. ANR-18-CE08-0021) project. J. Christensen acknowledges the support from the European Research Council (ERC) through the Starting Grant No. 714577 PHONOMETA and from the MINECO through a Ramon y Cajal Grant (No. RYC-2015-17156).Malléjac, M.; Merkel, A.; Sánchez-Dehesa Moreno-Cid, J.; Christensen, J.; Tournat, V.; Romero-García, V.; Groby, J. (2021). Experimental evidence of a hiding zone in a density-near-zero acoustic metamaterial. Journal of Applied Physics. 129(14):1-9. https://doi.org/10.1063/5.0042383S191291

Métamatériaux avec propriétés extraordinaires pour le contrôle des ondes acoustiques

Zero-index metamaterials, for which at least one of the effective parameters (density or dynamic compressibility for acoustics) vanishes, have received considerable attention in recent years. These materials have the particularity of inducing a considerable increase in the effective wavelength, thus offering numerous application possibilities, including, among others, propagation without phase change, acoustic hiding of diffusers, directivity control, etc. This PhD work focuses particularly on the near-zero effective density regime in acoustic metamaterials made of thin plates in air. Through an in-depth study of a periodic arrangement of thin elastic plates embedded in a waveguide, we have been able to explore analytically, numerically and experimentally some of the above effects. Particular attention is paid to the losses inherent to this type of system and their consequences on the expected behavior. We begin by studying numerically and experimentally observing a phase-change-free propagation through the metamaterial at a frequency in a stopband of the finite system. We then transpose the concept of photonic doping to acoustics. The addition of an impurity, here a well-chosen Helmholtz resonator, to the system allows to transform the regime of zero density into one where density and compressibility are simultaneously near zero. Thus, propagation without phase change is accompanied by a unitary transmission, due to the impedance matching of the system with the surrounding air. Finally, we study the possibility of performing acoustic hiding or masking of an object using the acoustic wavelength stretching offered by the zero density.Les métamatériaux à indice nul, pour lesquels au moins un des paramètres effectifs s’annule (densité ou compressibilité dynamique pour l’acoustique), ont fait l’objet d’une attention considérable au cours de ces dernières années. Ces matériaux ont la particularité d’induire une augmentation remarquable de la longueur d’onde effective, offrant ainsi de nombreuses possibilités d’application, incluant entre autres la propagation sans changement de phase, la dissimulation acoustique de diffuseurs, le contrôle de la directivité, etc. Ce travail de doctorat se concentre particulièrement sur le régime de densité effective quasi-nulle dans des métamatériaux acoustiques constitués de plaques fines dans l’air. Grâce à une étude approfondie d’un arrangement périodique de fines plaques élastiques encastrées dans un guide d’onde, nous avons pu explorer analytiquement, numériquement et expérimentalement certains des effets ci-dessus. Une attention particulière est portée sur les pertes inhérentes à ce type de système et à leurs conséquences sur les comportements attendus. Nous débutons par l’étude numérique et l’observation expérimentale d’une propagation sans changement de phase à travers le métamatériau, à une fréquence située dans une bande interdite du système fini. Nous transposons ensuite le concept de dopage photonique à l’acoustique. L’ajout dans le système d’une impureté, ici un résonateur de Helmholtz bien choisi, permet de transformer le régime de densité nulle en un régime où la densité et la compressibilité sont simultanément quasi-nulles. Ainsi, la propagation sans changement de phase est accompagnée d’une transmission unitaire, due à l’accord d’impédance du système avec l’air environnant. Nous étudions enfin la possibilité de réaliser une dissimulation ou un masquage acoustique d’un objet en utilisant l’extension de la longueur d’onde acoustique, offerte par la densité nulle

Doping of a plate-type acoustic metamaterial

International audienceWe theoretically, numerically, and experimentally investigate the feasibility of acoustic doping, i.e., changing one of the effective properties of a medium by adding an impurity, to achieve supersqueezing. This effect, characterized by perfect and zero-phase transmission, can be obtained with zero index media. In acoustics, zero-phase propagation can be achieved with a plate-type acoustic metamaterial (PAM) acting as a density-near- zero metamaterial (DNZ). We point out the possibility of modifying the compressibility of a DNZ medium by mounting a Helmholtz resonator in parallel with the PAM. We are then able to dope the system and to turn it into a density-and-compressibility-near-zero medium, thus allowing supersqueezing

Slow sound based delay-line acoustic metamaterial

[EN] Periodic structures composed of quarter-wavelength or Helmholtz resonators have been widely used in the design of acoustic metamaterials. An interesting phenomenon achievable through hybridization in such structures is the slow sound, which results from the strong dispersion produced by the local resonances. It gives rise to many applications such as deep subwavelength sound absorbers or metadiffusers. All the applications proposed so far have been analyzed only in the frequency domain (steady state). In this work, we propose a passive treatment that can be used in room acoustics, which requires considering the time domain and all multiple reflections. We analytically design a delay line from a metasurface made of Helmholtz resonators, using slow-sound propagation. We prove numerically and experimentally that such structures can delay a pulse and thus reproduce the sound perception of a propagation over a given distance, larger than the actual size of the treatment. The limitations of real-time pulse propagation, dispersion, and losses on audio fidelity are discussed.This work is funded by the Metaroom Project No. ANR-18-CE08-0021 and co-funded by ANR and RCG.Malléjac, M.; Sheng, P.; Tournat, V.; Romero-García, V.; Groby, JP. (2022). Slow sound based delay-line acoustic metamaterial. Physical Review Applied. 17(4):044035-1-044035-9. https://doi.org/10.1103/PhysRevApplied.17.044035044035-1044035-917

Plate-type acoustic metamaterials for acoustic absorption.

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