Impact wave attenuation using Maxwell-type oscillators in dissipative elastic metamaterials

2018 ◽  
Vol 143 (3) ◽  
pp. 1918-1918
Author(s):  
Sagr Alamri ◽  
Bing Li ◽  
Kwek Tze Tan
Keyword(s):  
Wave Attenuation ◽  
Impact Wave ◽  
Elastic Metamaterials

scholarly journals Numerical Modelling and Optimization of Two-Dimensional Phononic Band Gaps in Elastic Metamaterials with Square Inclusions

2021 ◽  
Vol 11 (7) ◽  
pp. 3124
Author(s):  
Alya Alhammadi ◽  
Jin-You Lu ◽  
Mahra Almheiri ◽  
Fatima Alzaabi ◽  
Zineb Matouk ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Tungsten Carbide ◽  
Composite Structure ◽  
Elastic Waves ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Filling Fraction ◽  
Carbide Composite ◽  
Elastic Metamaterials ◽  
Tungsten Carbide Composite

A numerical simulation study on elastic wave propagation of a phononic composite structure consisting of epoxy and tungsten carbide is presented for low-frequency elastic wave attenuation applications. The calculated dispersion curves of the epoxy/tungsten carbide composite show that the propagation of elastic waves is prohibited inside the periodic structure over a frequency range. To achieve a wide bandgap, the elastic composite structure can be optimized by changing its dimensions and arrangement, including size, number, and rotation angle of square inclusions. The simulation results show that increasing the number of inclusions and the filling fraction of the unit cell significantly broaden the phononic bandgap compared to other geometric tunings. Additionally, a nonmonotonic relationship between the bandwidth and filling fraction of the composite was found, and this relationship results from spacing among inclusions and inclusion sizes causing different effects on Bragg scatterings and localized resonances of elastic waves. Moreover, the calculated transmission spectra of the epoxy/tungsten carbide composite structure verify its low-frequency bandgap behavior.

Elastic wave propagation in metamaterial rods with periodic shunted piezo-patches

2021 ◽  
Vol 263 (2) ◽  
pp. 4303-4311
Author(s):  
Edson J.P. de Miranda ◽  
Edilson D. Nobrega ◽  
Leopoldo P.R. de Oliveira ◽  
José M.C. Dos Santos
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Wave Attenuation ◽  
Periodic Structures ◽  
Band Gaps ◽  
Low Frequencies ◽  
Periodic Arrays ◽  
Extended Plane ◽  
Elastic Metamaterials ◽  
Piezoelectric Structures

The wave propagation attenuation in low frequencies by using piezoelectric elastic metamaterials has been developed in recent years. These piezoelectric structures exhibit abnormal properties, different from those found in nature, through the artificial design of the topology or exploring the shunt circuit parameters. In this study, the wave propagation in a 1-D elastic metamaterial rod with periodic arrays of shunted piezo-patches is investigated. This piezoelectric metamaterial rod is capable of filtering the propagation of longitudinal elastic waves over a specified range of frequency, called band gaps. The complex dispersion diagrams are obtained by the extended plane wave expansion (EPWE) and wave finite element (WFE) approaches. The comparison between these methods shows good agreement. The Bragg-type and locally resonant band gaps are opened up. The shunt circuits influence significantly the propagating and the evanescent modes. The results can be used for elastic wave attenuation using piezoelectric periodic structures.

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.

Experimental Study of the Effects of Different Floating Breakwater on Wave Absorbing

2014 ◽  
Author(s):  
Lilan Zhou ◽  
Keqiang Chen ◽  
Shihong Zhai ◽  
Zhao Niu ◽  
Xiaoming Hu
Keyword(s):  
Cross Section ◽  
Wave Attenuation ◽  
Solid Wall ◽  
Circular Cross Section ◽  
Wave Period ◽  
Geometrical Configuration ◽  
Ocean Engineering ◽  
Impact Wave ◽  
Floating Breakwater ◽  
Soft Wall

As the development of ocean engineering, safety construction is becoming a significant aspect that attracted more and more attention. The general aims of this paper were to present the effects of different floating breakwater on wave absorbing and provide a basis for the design of floating breakwater of an offshore project. Three different kinds of floating breakwater were studied; they are soft wall-sided pontoon, solid wall-sided pontoon and a circular cross-section breakwater filled with water. Various factors including wave period, wave steepness and geometrical characteristics were considered. The results had shown that the three proposed floating breakwater revealed favorable performance and the geometrical configuration could impact wave attenuation significantly. The circular cross-section breakwater had greater effects on wave absorbing compared with two other floating breakwaters, more detailed experiments were conducted to the circular cross-section breakwater, a V-shaped floating breakwater consists of two single circular cross-section breakwater were studied, the effects of angle of the two singles, wave period and wave height were considered. The results revealed that the geometrical configuration and water depth could impact wave attenuation and mooring force significantly. Researches are expected to offer some information for the design of floating breakwater for an offshore project.

THE ANALYSIS OF ULTRASONIC WAVE ATTENUATION SPECTRA IN STEELS

1983 ◽  
Vol 44 (C9) ◽  
pp. C9-337-C9-340 ◽  
Author(s):  
R. L. Smith ◽  
W. N. Reynolds ◽  
S. Perring
Keyword(s):  
Ultrasonic Wave ◽  
Wave Attenuation

Bulk drag coefficient of a subaquatic vegetation subjected to irregular waves: Influence of Reynolds and Keulegan-Carpenter numbers

2020 ◽  
pp. 34-42
Author(s):  
Thibault Chastel ◽  
Kevin Botten ◽  
Nathalie Durand ◽  
Nicole Goutal
Keyword(s):  
Drag Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Empirical Relationship ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Geometrical Parameters ◽  
Flume Experiments ◽  
Seagrass Meadows ◽  
Artificial Vegetation

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs, Tp, water depth hw) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio (< 0.2) the wave attenuation is negligible. From each experiment, a bulk drag coefficient has been extracted following the energy dissipation model for irregular non-breaking waves developed by Mendez and Losada (2004). This model, based on the assumption that the energy loss over the species meadow is essentially due to the drag force, takes into account both wave and vegetation parameter. Finally, we found an empirical relationship for Cd depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

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