scholarly journals Vortex-type elastic structured media and dynamic shielding

2012 ◽  
Vol 468 (2146) ◽  
pp. 3027-3046 ◽  
Author(s):  
M. Brun ◽  
I. S. Jones ◽  
A. B. Movchan
Keyword(s):  
Elastic Waves ◽  
Continuous Medium ◽  
Lattice System ◽  
Periodic Lattice ◽  
Two Dimensional ◽  
Metamaterial Structure ◽  
Structured Media ◽  
Analytical Work

The paper presents an approach to modelling a novel elastic metamaterial structure that possesses non-trivial dispersion features. A system of spinners has been embedded into a two-dimensional periodic lattice system. The analysis of the motion of the spinners is used to derive an expression for a ‘chiral term’ in the equations describing the dynamics of the lattice. Dispersion of elastic waves is shown to possess innovative filtering and polarization properties induced by the vortex-type nature of the structured media. The related effective behaviour in a continuous medium is implemented to build a shielding cloak around an obstacle. Analytical work is accompanied by numerical illustrations.

Elastic Metamaterials With Low-Frequency Passbands Based on Lattice System With On-Site Potential

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yongquan Liu ◽  
Xiaohui Shen ◽  
Xianyue Su ◽  
C. T. Sun
Keyword(s):  
Elastic Waves ◽  
Present Method ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Lattice System ◽  
Two Dimensional ◽  
High Frequencies ◽  
Elastic Metamaterials

An elastic metamaterial with a low-frequency passband is proposed by imitating a lattice system with linear on-site potential. It is shown that waves can only propagate in the tunable passband. Then, two kinds of elastic metamaterials with double passbands are designed. Great wave attenuation performance can be obtained at frequencies between the two passbands for locally resonant type metamaterials, and at both low and high frequencies for the diatomic type metamaterials. Finally, the strategy to design two-dimensional (2D) metamaterials is demonstrated. The present method can be used to design new types of small-size waveguides, filters, and other devices for elastic waves.

Wave Manipulation of Two-Dimensional Periodic Lattice by Parametric Excitation

2019 ◽  
Vol 87 (1) ◽  
Author(s):  
Xiao-Dong Yang ◽  
Qing-Dian Cui ◽  
Wei Zhang
Keyword(s):  
Parametric Excitation ◽  
Elastic Waves ◽  
High Frequency ◽  
Low Frequency ◽  
Waveguide Structure ◽  
Phononic Crystals ◽  
Periodic Lattice ◽  
Two Dimensional ◽  
Time Dynamic ◽  
Mechanical Waves

Abstract Phononic crystals composed of delicately designed periodic units are used to control spatial and spectral properties of acoustic or elastic waves. The ability to manipulate transmitting waves in a real-time dynamic manner provides a new concept in programable phononic crystals and metamaterials. In this study, the mechanical waves and bandgaps in a two-dimensional spring-mass array loaded by high-frequency parametric excitation have been investigated by both analytical and numerical methods. It is found that the high-frequency parametric excitation provides an equivalent additional stiffness which leads to low-frequency bandgaps. By tuning the parametric excitation, the versatility of such a dynamic modulating technique has been presented. The waveguide structure has also been designed and studied by non-uniformly distributed parametric excitations.

A CALIBRATED MODEL SEISMIC SYSTEM

Geophysics ◽  
1972 ◽  
Vol 37 (3) ◽  
pp. 445-455 ◽  
Author(s):  
C. N. G. Dampney ◽  
B. B. Mohanty ◽  
G. F. West
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Elastic Waves ◽  
Critical Examination ◽  
Two Dimensional ◽  
Linear Filtering ◽  
Analog Model ◽  
Basic Assumptions ◽  
Electronic Circuitry ◽  
Seismic System

Simple electronic circuitry and axially polarized ceramic transducers are employed to generate and detect elastic waves in a two‐dimensional analog model. The absence of reverberation and the basic simplicity. of construction underlie the advantages of this system. If the form of the fundamental wavelet in the model itself, as modified by the linear filtering effects of the remainder of the system, can be found, then calibration is achieved. This permits direct comparison of theoretical and experimental seismograms for a given model if its impulse response is known. A technique is developed for calibration and verified by comparing Lamb’s theoretical and experimental seismograms for elastic wave propagation over the edge of a half plate. This comparison also allows a critical examination of the basic assumptions inherent in a model seismic system.

Effect of the number of defect particles on the structure and dispersion relation of a two-dimensional dust lattice system

2021 ◽  
Author(s):  
Rangyue Zhang ◽  
Guannan Shi ◽  
Hanyu Tang ◽  
Yang Liu ◽  
Yanhong Liu ◽  
...  
Keyword(s):  
Dispersion Relation ◽  
Lattice System ◽  
Two Dimensional
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