Emerging topics in nanophononics and elastic, acoustic, and mechanical metamaterials: an overview

Abstract

This broad review summarizes recent advances and "hot" research topics in nanophononics and elastic, acoustic, and mechanical metamaterials based on results presented by the authors at the EUROMECH 610 Colloquium held on April 25-27, 2022 in Benicássim, Spain. The key goal of the colloquium was to highlight important developments in these areas, particularly new results that emerged during the last two years. This work thus presents a "snapshot" of the state-of-the-art of different nanophononics- and metamaterial-related topics rather than a historical view on these subjects, in contrast to a conventional review article. The introduction of basic definitions for each topic is followed by an outline of design strategies for the media under consideration, recently developed analysis and implementation techniques, and discussions of current challenges and promising applications. This review, while not comprehensive, will be helpful especially for early-career researchers, among others, as it offers a broad view of the current state-of-the-art and highlights some unique and flourishing research in the mentioned fields, providing insight into multiple exciting research directions.

Keywords: acoustics; additive manufacturing; mechanics; metamaterials; optomechanics; wave dynamics.

Figure 1:

The NOEMS platform for room temperature operation at 2 GHz. The top left inset shows the normalized transmission (black line) and normalized reflection (red line). Reprinted with permission from D. Navarro-Urrios, M. F. Colombano, G. Arregui, et al. ACS Photonics, 2022, 9, 2, 413–419. Copyright 2022 American Chemical Society.

Figure 2:

Examples of phononic materials. (a) Meta-beam with quadruple-mode resonators (adapted from Figure 1 published in: Kentaro Fujita; Motonobu Tomoda; Oliver B. Wright; Osamu Matsuda; Appl. Phys. Lett. 115, 081905 (2019), Copyright © 2019); (b) metasurface with aperiodic resonators; (c) octet panel with a highlighted unit cell; (d) 3D phononic material with roton-like dispersion (originally published in Ref. [86]); (e) flexible metamaterial with a “rotating-square” structure (adapted from: B. Deng, P. Wang, Q. He, V. Tournat, K. Bertoldi, Metamaterials with amplitude gaps for elastic solitons, Nat. Commun., Nature Research, 2018); (f–g) self-assembled lattices within 2D magnetic boundaries with square and quasi-crystal configurations.

Figure 3:

Nonlinear and time-varying effects in elastic metamaterials. (a) Numerically estimated deformation at vertically applied ϵ ^yy = −6% on a flexible metamaterial comprising 21 × 60 squares with localized pinning defects separated by 10 holes. (Adapted from [105]). (b) Wave dispersion in linear and nonlinear homogeneous materials and in linear and nonlinear elastic metamaterials. The intensity of the finite-strain nonlinearity increases with the wave amplitude. (Adapted from Ref. [112] with permission from the Royal Society). (c) A numerical model for right-going surface waves with a right-going modulating wave with the sub-figures showing the time history and frequency content of the point force applied at the source. (Reprinted from Journal of Mechanics and Physics of Solids, vol. 145, A. Palermo, P. Celli, B. Yousefzadeh, et al., “Surface wave non-reciprocity via time-modulated metamaterials”, p. 104181, Copyright © 2020, with permission from Elsevier).

Figure 4:

Acoustic metamaterials and metasurfaces. (a) Schematic representation of a diffuser with spatiotemporally modulated input impedance and the associated incident and scattered plane wave fields. (Published in Ref. [189]). (b) Fabricated topological WG insulator with a triangular domain wall. The inset shows the photograph of the cylinder trimers wrapped with a CNT film. (Material from Figure 3 in Hu, B., Zhang, Z., Zhang, H. et al. Non-Hermitian topological whispering gallery, Nature, published 2021, publisher – Nature, ISSN 1476–4687). (c) Thermoacoustic amplifier: (left-top) scaled representation of the unit cell with the temperature distribution indicated by colors; (right-top) the photography of the elements of the thermoacoustic cell and (bottom) a schematic view of the experimental setup for measuring the scattering matrix of the thermoacoustic amplifier. (Reprinted from Physical Review B, vol. 104, C. Olivier, G. Poignand, et al., “Nonreciprocal and even Willis couplings in periodic thermoacoustic amplifiers”, p. 184109, Copyright © 2021, Publisher – APS Physics).

Figure 5:

Mechanical metamaterials. (a) By controlling the values of Poisson’s ratio, one can control the out-of-plane curvature of meta-plates (adapted from M. J. Mirzaali, et al., Advanced Materials, 33(30), p. 2008082 (2021)); (b) a wider range of properties can be achieved by intruding multiple materials in the structure of the mechanical metamaterials (Reprinted from M. J. Mirzaali et al. “Multi-material 3D printed mechanical metamaterials: Rational design of elastic properties through spatial distribution of hard and soft phases”, Appl. Phys. Lett. 113, 241903 (2018) with the permission of AIP Publishing); (c) numerical and experimental images of a multiphase composite with stiff inclusions and voids in an undeformed state and loaded in the x direction (adapted from J. Li, V. Slesarenko and S. Rudykh, Soft Matter, 14, 6171 (2018); (d) viscoelastic bi-beams buckle to left and right in response to the applied strain rate (adapted from S. Janbaz, et al., Science Advances, 6(25), p. eaba0616 (2020)); (e) A viscoelastic micro gripper powered by a bi-beam (adapted from S. Janbaz, et al., arXiv:2206.15168); (f) viscoelastic oligomodal metamaterials exhibit different global buckling modes once compressed slow or fast (adapted from A. Bossart, et al., PNAS, 118(21), p. e2018610118 (2021)).