scholarly journals Wave propagation retrieval method for metamaterials: Unambiguous restoration of effective parameters

2009 ◽  
Vol 80 (19) ◽  
Author(s):  
Andrei Andryieuski ◽  
Radu Malureanu ◽  
Andrei V. Lavrinenko
Keyword(s):  
Wave Propagation ◽  
Effective Parameters ◽  
Retrieval Method

scholarly journals Fractal Acoustic Metamaterials with Subwavelength and Broadband Sound Insulation

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Yu Liu ◽  
Meng Chen ◽  
Wenshuai Xu ◽  
Tao Yang ◽  
Dongliang Pei ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Acoustic Metamaterials ◽  
The Finite Element Method ◽  
Transmission Losses ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Sound Control ◽  
S Parameter ◽  
Broadband Sound

We construct new fractal acoustic metamaterials by coiling up space, which can allow subwavelength-scale and broadband sound insulation to be achieved. Using the finite element method and the S-parameter retrieval method, the band structures, the effective parameters, and the transmission losses of these acoustic metamaterials with different fractal orders are researched individually. The results illustrate that it is easy to form low-frequency bandgaps using these materials and thus achieve subwavelength-scale sound control. As the number of fractal orders increase, more bandgaps appear. In particular, in the ΓX direction of the acoustic metamaterial lattice, more of these wide bandgaps appear in different frequency ranges, thus providing broadband sound insulation and showing promise for use in engineering applications.

Study on dynamic effective parameters of bilayer perforated thin-plate acoustic metamaterials

2020 ◽  
pp. 2150048
Author(s):  
Yicai Xu ◽  
Jiu Hui Wu ◽  
Yongqing Cai
Keyword(s):  
Thin Plate ◽  
Thin Plates ◽  
Formation Mechanisms ◽  
Acoustic Metamaterials ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Acoustic Metamaterial ◽  
Resonance Frequencies ◽  
Wave Normal ◽  
Mass Type

In this paper, dynamic effective parameters of mass-type and stiffness-type bilayer perforated thin-plate acoustic metamaterials (MBPM and SBPM) are investigated by simulations and experiments. Dynamic effective parameters are calculated by the retrieval method, and formation mechanisms of special effective parameters are analyzed by simulated fields. Divergent effective parameters are produced by anti-resonances of coupled perforations or coupled perforated thin-plates, zero effective parameters are produced by resonances of coupled perforated thin-plates. The impacts of perforation parameters on dynamic effective parameters for symmetric and asymmetric BPMs are systemically studied, the simulated and experimental results both show that variation trends of resonance and anti-resonance frequencies of mass-type bilayer perforated thin-plate acoustic metamaterial (MBPM) are different from stiffness-type bilayer perforated thin-plate acoustic metamaterial (SBPM), because perforations mainly change system mass in MBPM and system stiffness in SBPM, respectively. Dynamic effective parameters are bi-anisotropic in asymmetric BPM, and doubly negative effective parameters are achieved by coupled perforations when plan wave normal incident from the side with smaller perforation parameters. A modified retrieval method is proposed to calculate unified effective parameters for the asymmetric BPM, and the unified effective parameters equal to averaged effective parameters of two symmetric BPMs. This work systematically studies dynamic effective parameters of bilayer perforated structures, which has a great guiding significance in design of perforated acoustic devices.

scholarly journals Wave propagation retrieval method for chiral metamaterials

2010 ◽  
Vol 18 (15) ◽  
pp. 15498 ◽  
Author(s):  
Andrei Andryieuski ◽  
Radu Malureanu ◽  
Andrei V. Lavrinenko
Keyword(s):  
Wave Propagation ◽  
Retrieval Method ◽  
Chiral Metamaterials

Obtaining Directly Quasi-Square Open Ring FSS Constitutive Effective Parameters by Using Coupled WCIP - Retrieval Method

2019 ◽  
Vol 397 ◽  
pp. 187-199
Author(s):  
Saida Mellal ◽  
Toufik Ziar ◽  
Hichem Farh ◽  
Khalid Hati ◽  
Badreddine Zemmal ◽  
...  
Keyword(s):  
Frequency Selective Surface ◽  
Electric Permittivity ◽  
Scattering Parameters ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Matlab Program ◽  
Open Ring ◽  
Analytical Formulas ◽  
Frequency Selective ◽  
Constitutive Parameters

We propose here a method witch analyze the behavior of Quasi-square open ring frequency selective surface (FSS) by using an approach based on the wave iterative concept procedure method (WCIP) coupled to Retrieval from Scattering Parameters method . The scattering parameters calculated by WCIP for a Quasi-square open ring FSS are used, in analytical formulas, to calculate directly observable effective constitutive parameters (relative electric permittivity εreff , magnetic permeability μreff and refractive index n ) of a frequency selective surface. Results of effective constitutive parameters for a Quasi-square open ring FSS structure are presented by Simulation using MATLAB program codes translating the implementation of the proposed approach.

scholarly journals Labyrinthine Structure with Subwavelength and Broadband Sound Insulation

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Heng Jiang ◽  
Yu Liu ◽  
Wenshuai Xu ◽  
Tao Yang ◽  
Dongliang Pei ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Low Frequency ◽  
Good Control ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Sound Waves ◽  
Effective Parameters ◽  
Retrieval Method ◽  
S Parameter ◽  
Broadband Sound

In this text, the combination of spiral structure and zigzag channels is introduced to design labyrinthine structures, in which sound waves can propagate alternately in the clockwise and counterclockwise directions. Finite element method and S-parameter retrieval method are used to calculate band structures, effective parameters, and transmission properties of the structures. The influences of different structural parameters on their acoustic properties are also studied. These results show labyrinthine structures have multiple bandgaps in the range of 0 Hz–1000 Hz, and the proportion of bandgaps exceeds 33%, which indicates labyrinthine structures have good broadband properties. The normalized frequency of the lowest bandgaps is far smaller than 1, which indicates the structures take good control of sound waves on subwavelength scale. Combining units with different structural parameters can achieve better sound insulation. This research provides a new kind of space-coiling structure for low-frequency and broadband sound waves control, which have excellent application prospects.

scholarly journals Causal homogenization of metamaterials

Nanophotonics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 1063-1069 ◽  
Author(s):  
SeokJae Yoo ◽  
Suyeon Lee ◽  
Jong-Ho Choe ◽  
Q-Han Park
Keyword(s):  
Effective Thickness ◽  
Causality Condition ◽  
Phase Ambiguity ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Minimum Error ◽  
Homogenization Scheme ◽  
Logarithm Function ◽  
Parameter Retrieval ◽  
Error Condition

AbstractWe propose a homogenization scheme for metamaterials that utilizes causality to determine their effective parameters. By requiring the Kramers-Kronig causality condition in the homogenization of metamaterials, we show that the effective parameters can be chosen uniquely, in contrast to the conventional parameter retrieval method which has unavoidable phase ambiguity arising from the multivalued logarithm function. We demonstrate that the effective thickness of metamaterials can also be determined to a specific value by saturating the minimum-error condition for the causality restriction. Our causal homogenization provides a robust and accurate characterization method for metamaterials.

scholarly journals On the homogenization of the acoustic wave propagation in perforated ducts of finite length for an inviscid and a viscous model

2018 ◽  
Vol 474 (2210) ◽  
pp. 20170708 ◽  
Author(s):  
Adrien Semin ◽  
Kersten Schmidt
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Near Field ◽  
Basis Functions ◽  
Effective Parameters ◽  
Acoustic Wave Propagation ◽  
Absorption Properties ◽  
Geometrical Properties ◽  
Viscous Boundary ◽  
Transmission And Absorption

The direct numerical simulation of the acoustic wave propagation in multiperforated absorbers with hundreds or thousands of tiny openings would result in a huge number of basis functions to resolve the microstructure. One is, however, primarily interested in effective and so homogenized transmission and absorption properties and how they are influenced by microstructure and its endpoints. For this, we introduce the surface homogenization that asymptotically decomposes the solution in a macroscopic part, a boundary layer corrector close to the interface and a near-field part close to its ends. The effective transmission and absorption properties are expressed by transmission conditions for the macroscopic solution on an infinitely thin interface and corner conditions at its endpoints to ensure the correct singular behaviour, which are intrinsic to the microstructure. We study and give details on the computation of the effective parameters for an inviscid and a viscous model and show their dependence on geometrical properties of the microstructure for the example of Helmholtz equation. Numerical experiments indicate that with the obtained macroscopic solution representation one can achieve an high accuracy for low and high porosities as well as for viscous boundary conditions while using only a small number of basis functions.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

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