Metaclusters for the Full Control of Mechanical Waves

Paćko, Paweł; Norris, Andrew N.; Torrent, Daniel

doi:10.1103/physrevapplied.15.014051

Cited by 17 publications

(7 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This represents an opportunity for the control of elastic waves via a specified configuration of voids. We term this a void metacluster , with terminology inspired by [27]. Furthermore, given that in general, metamaterials consist of multiple subwavelength scatterers, we consider that the above are important sub-problems from which to potentially fabricate novel elastodynamic metamaterials for the control of elastic waves.…”

Section: Elastodynamic Scattering and The Giant Monopole Resonancementioning

confidence: 99%

See 1 more Smart Citation

Deeply subwavelength giant monopole elastodynamic metacluster resonators

2022

View full text Add to dashboard Cite

The giant monopole resonance is a well-known phenomenon, employed to tune the dynamic response of composite materials comprising voids in an elastic matrix which has a bulk modulus much greater than its shear modulus, e.g. elastomers. This low frequency resonance (e.g. λ p / a ≈ 100 for standard elastomers, where λ p and a are the compressional wavelength and void radius, respectively) has motivated acoustic material design over many decades, exploiting the subwavelength regime. Despite this widespread use, the manner by which the resonance arising from voids in close proximity is affected by their interaction is not understood. Here, we illustrate that for planar elastodynamics (circular cylindrical voids), coupling due to near-field shear significantly modifies the monopole (compressional) resonant response. We show that by modifying the number and configuration of voids in a metacluster, the directionality, scattering amplitude and resonant frequency can be tailored and tuned. Perhaps most notably, metaclusters deliver a lower frequency resonance than a single void. For example, two touching voids deliver a reduction in resonant frequency of almost 16% compared with a single void of the same volume. Combined with other resonators, such metaclusters can be used as meta-atoms in the design of elastic materials with exotic dynamic material properties.

show abstract

Section: Elastodynamic Scattering and The Giant Monopole Resonancementioning

confidence: 99%

“…In [27], the concept of a metacluster was introduced. This is a collection of scatterers that is employed to tune the far-field response due to some incident field.…”

Section: Introductionmentioning

confidence: 99%

Deeply subwavelength giant monopole elastodynamic metacluster resonators

2022

View full text Add to dashboard Cite

show abstract

“…The unique arrangement of components in metamaterials gives rise to exotic interactions with acoustic waves at large wavelengths. This has many applications such as wave steering [5], cloaking [6,7], and focusing [3,8,9]. The traditional method of designing acoustic cloaking devices involves direct computer simulation [10], topology optimization [11], stochastic optimization [12,13], and gradient based optimization [7,14] of the acoustic response based on the structure.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Cloak Design via Machine Learning

Tran,

Amirkulova,

Khatami

2021

Preprint

View full text Add to dashboard Cite

Acoustic metamaterials are engineered microstructures with special mechanical and acoustic properties enabling exotic effects such as wave steering, focusing and cloaking. The design of acoustic cloaks using scattering cancellation has traditionally involved the optimization of metamaterial structure based on direct computer simulations of the total scattering cross section (TSCS) for a large number of configurations. Here, we work with sets of cylindrical objects confined in a region of space and use machine learning methods to streamline the design of 2D configurations of scatterers with minimal TSCS demonstrating cloaking effect at discrete sets of wavenumbers. After establishing that artificial neural networks are capable of learning the TSCS based on the location of cylinders, we develop an inverse design algorithm, combining variational autoencoders and the Gaussian process, for predicting optimal arrangements of scatterers given the TSCS. We show results for up to eight cylinders and discuss the efficiency and other advantages of the machine learning approach.

show abstract

“…and the total scattering cross-section 𝜎 𝑠𝑐𝑎 , which is defined as the ratio of the scattered field flux to the incident field flux [29], is computed as [131] 𝜎…”

Section: Excitationmentioning

confidence: 99%

“…In this chapter, localized interface modes will be designed in mechanical systems, considering a quasi-periodic line of scatterers embedded in a two-dimensional elastic plate. MST has been applied to the study of these structures [91][92][93]. This method contrasts against the other methods used for analysing these structures, based on super-cells and Floquet-Bloch theory.…”

Section: Introductionmentioning

confidence: 99%

Trapping flexural waves in thin elastic plates by complex engineered surfaces

Marc

View full text Add to dashboard Cite

The main objective of this PhD thesis has been to design geometrical structures of resonators on top of a thin elastic plate for trapping waves that propagate through the medium in a reduced space. High density of modes in a wide frequency range is desired, as it can be appealing for developing mechanical wave control devices.Structures discussed throughout this work have been analysed using multiple scattering theory. This mathematical tool has proved to be really adequate when treating with point-like interactions between resonators and the continuum medium, as is the case in our systems.In the first place, a mechanical analogue for the twisted bilayer structure has been studied. This system is based on two periodic lattices superimposed with a relative rotation angle between them. It has recently attracted the attention of the scientific community due to its exotic properties as conductor/isolator. In this work, we will study a mechanism for describing the behavior of the eigenmodes of the structure based on the dimerized interaction between resonators.Quasi-periodic one-dimensional distribution of scatterers offers the possibility of confining waves that propagate through the medium, and presents robustness against disorder based on its topological protection. This work has proven the possibility of confining mechanical waves in a two-dimensional space using one-dimensional quasi-periodic structures, simplifying the necessary system for confining waves and showing similar results to the same kind of structures applied in other domains.Lastly, solutions for having bound states in the continuum (BICs) within a circular arrangement of scatterers have been studied and developed. These solutions to the wave equation allow to have infinite lifetime modes that do not propagate through the rest of the system, and therefore present perfect confinement. In this work, solutions have been found both for flexural waves in thin elastic plates, and for two-dimensional acoustic waveguides.

show abstract

Metaclusters for the Full Control of Mechanical Waves

Cited by 17 publications

References 22 publications

Deeply subwavelength giant monopole elastodynamic metacluster resonators

Deeply subwavelength giant monopole elastodynamic metacluster resonators

Acoustic Cloak Design via Machine Learning

Trapping flexural waves in thin elastic plates by complex engineered surfaces

Contact Info

Product

Resources

About