scholarly journals Investigation on the Band Gap and Negative Properties of Concentric Ring Acoustic Metamaterial

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Meng Chen ◽  
Dan Meng ◽  
Heng Jiang ◽  
Yuren Wang
Keyword(s):  
Band Gap ◽  
Effective Mass ◽  
Coupling Effect ◽  
Mass Density ◽  
Band Gaps ◽  
Acoustic Metamaterials ◽  
Concentric Ring ◽  
Resonance Modes ◽  
Negative Effective Mass ◽  
Single Oscillator

The acoustic characteristics of 2D single-oscillator, dual-oscillator, and triple-oscillator acoustic metamaterials were investigated based on concentric ring structures using the finite element method. For the single-oscillator, dual-oscillator, and triple-oscillator models investigated here, the dipolar resonances of the scatterer always induce negative effective mass density, preventing waves from propagating in the structure, thus forming the band gap. As the number of oscillators increases, relative movements between the oscillators generate coupling effect; this increases the number of dipolar resonance modes, causes negative effective mass density in more frequency ranges, and increases the number of band gaps. It can be seen that the number of oscillators in the cell is closely related to the number of band gaps due to the coupling effect, when the filling rate is of a certain value.

Multi-cavity coupling acoustic metamaterials with low-frequency broad band gaps based on negative mass density

2016 ◽  
Vol 30 (23) ◽  
pp. 1650317
Author(s):  
Chuanhui Yang ◽  
Jiu Hui Wu ◽  
Songhua Cao ◽  
Li Jing
Keyword(s):  
Band Gap ◽  
Mass Density ◽  
Resonant Cavity ◽  
Broad Band ◽  
Low Frequency ◽  
Band Gaps ◽  
Acoustic Metamaterials ◽  
Negative Mass ◽  
Closed Cavity ◽  
Cavity Coupling

This paper studies a novel kind of low-frequency broadband acoustic metamaterials with small size based on the mechanisms of negative mass density and multi-cavity coupling. The structure consists of a closed resonant cavity and an open resonant cavity, which can be equivalent to a homogeneous medium with effective negative mass density in a certain frequency range by using the parameter inversion method. The negative mass density makes the anti-resonance area increased, which results in broadened band gaps greatly. Owing to the multi-cavity coupling mechanism, the local resonances of the lower frequency mainly occur in the closed cavity, while the local resonances of the higher frequency mainly in the open cavity. Upon the interaction between the negative mass density and the multi-cavity coupling, there exists two broad band gaps in the range of 0–1800 Hz, i.e. the first-order band gap from 195 Hz to 660 Hz with the bandwidth of 465 Hz and the second-order band gap from 1157 Hz to 1663 Hz with the bandwidth of 506 Hz. The acoustic metamaterials with small size presented in this paper could provide a new approach to reduce the low-frequency broadband noises.

Negative Effective Mass Density of One-Dimensional Hierarchical Metacomposite

2015 ◽  
Vol 82 (3) ◽  
Author(s):  
Xiyue An ◽  
Fangfang Sun ◽  
Peishi Yu ◽  
Hualin Fan ◽  
Shiping He ◽  
...  
Keyword(s):  
Effective Mass ◽  
Mass Density ◽  
Rigid Bodies ◽  
Band Gaps ◽  
Mass Ratio ◽  
One Dimensional ◽  
Negative Effective Mass ◽  
Specific Frequency ◽  
The Relationship ◽  
Internal Resonators

A theoretical model of one-dimensional (1D) hierarchical metacomposite with internal resonators was proposed to generate negative effective mass over specific frequency ranges. Different from the single-resonator microstructure, the current hierarchical metamaterial with multilevel resonators was constructed by a series of springs and rigid bodies. The general formula of the current hierarchical metamaterial model was induced to reveal the relationship between the effective mass and the forcing frequency. It is found that the hierarchical metamaterial with multilevel resonators generates multifrequency band gaps with negative effective masses. The number of the band gaps equals to the order of the hierarchy. The total bandwidth for the negative effective mass increases with the hierarchy, meanwhile increasing the mass ratio can also obviously increase the bandwidth generating negative effective mass.

scholarly journals Band Gaps and Vibration Isolation of a Three-dimensional Metamaterial with a Star Structure

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3812 ◽  
Author(s):  
Heng Jiang ◽  
Mangong Zhang ◽  
Yu Liu ◽  
Dongliang Pei ◽  
Meng Chen ◽  
...  
Keyword(s):  
Band Gap ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Mass Density ◽  
Three Dimensional ◽  
Low Frequency ◽  
Band Gaps ◽  
Acoustic Metamaterials ◽  
Star Structure

Elastic metamaterials have promising applications in wave control and vibration isolation, due to their extraordinary characteristics, e.g., negative Poisson ratio, band gaps, effective negative mass density and effective negative modulus. How to develop new functional metamaterials using a special structure has always been a hot topic in this field. In this study, a three-dimensional (3D) star structure is designed to construct metamaterials with both negative static and dynamic properties. The results show that the 3D star structure formed a wide band gap at lower frequency and had a negative Poisson’s ratio. Different from conventional acoustic metamaterials, the main physical mechanism behind the low-frequency band gap of the 3D star structure is the resonance mode formed by the bending deformation of each rib plate, which made it easier to achieve effective isolation of low-frequency elastic waves with a low mass density. In addition, many structural parameters of the 3D star structure can be modulated to effectively adjust the band gap frequency by changing the angle between the concave nodes and aspect ratio. This study provides a new way to design the 3D acoustic metamaterials and develop the lightweight vibration isolation devices.

Wave propagation in acoustic metamaterials with resonantly shunted cross-shape piezos

2018 ◽  
Vol 29 (13) ◽  
pp. 2744-2753 ◽  
Author(s):  
Shengbing Chen
Keyword(s):  
Wave Propagation ◽  
Band Gap ◽  
Vibration Isolation ◽  
Band Gaps ◽  
Acoustic Metamaterials ◽  
Resonant Frequencies ◽  
Piezoelectric Patch ◽  
Transmission Properties ◽  
Gap Width ◽  
Band Gap Width

Cross-shape piezoelectric patches were originally proposed to improve the band-gap properties of acoustic metamaterials with shunting circuits. The dispersion curves are characterized through the application of finite element method. Also, the theoretical band-gap predictions are verified by simulation results obtained from COMSOL. The investigation results show that the proposed scheme distinguishes itself from the conventional square patches by broader band gaps, whose bandwidth is almost doubled. The inherent capacitance of the piezoelectric patch is strongly related to the boundary conditions, so the local resonant band gap is strongly affected by the shape of piezoelectric patches as well. As a result, the band-gap width and location of metamaterials with different shape patches are rather different, even with the same size patches. Also, negative modulus (NM) and Poisson’s ratio were observed around the resonant frequencies. The transmission properties of finite periods agree well with band-gap predictions. An obvious attenuation zone (AZ) is produced around the band-gap location, in which the wave propagation is decayed strongly. Similarly, the width of AZ of the proposed metamaterial is much larger than that of the conventional one. Hence, the proposed scheme demonstrates more advantages in the application to vibration isolation when compared with the conventional.

Characteristics of Band Gap and Low-frequency Wave Propagation of Mechanically Tunable Phononic Crystals with Scatterers in Periodic Porous Elastomeric Matrices

2021 ◽  
pp. 1-34
Author(s):  
Shaowu Ning ◽  
Dongyang Chu ◽  
Fengyuan Yang ◽  
Heng Jiang ◽  
Zhanli Liu ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Coupling Effect ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Dynamic Responses ◽  
Acoustic Metamaterials ◽  
Frequency Wave ◽  
Strong Coupling Effect ◽  
The Matrix

Abstract The characteristics of passive responses and fixed band gaps of phononic crystals (PnCs) limit their possible applications. For overcoming this shortcoming, a class of tunable PnCs comprised of multiple scatterers and soft periodic porous elastomeric matrices are designed to manipulate the band structures and directionality of wave propagation through the applied deformation. During deformation, some tunable factors such as the coupling effect of scatterer and hole in the matrix, geometric and material nonlinearities, and the rearrangement of scatterer are activated by deformation to tune the dynamic responses of PnCs. The roles of these tunable factors in the manipulation of dynamic responses of PnCs are investigated in detail. The numerical results indicate that the tunability of the dynamic characteristic of PnCs is the result of the comprehensive function of these tunable factors mentioned above. The strong coupling effect between the hole in the matrix and the scatterer contributes to the formation of band gaps. The geometric nonlinearity of matrix and rearrangement of scatterer induced by deformation can simultaneously tune the band gaps and the directionality of wave propagation. However, the matrix's material nonlinearity only adjusts the band gaps of PnCs and does not affect the directionality of wave propagation in them. The research extends our understanding of the formation mechanism of band gaps of PnCs and provides an excellent opportunity for the design of the optimized tunable PnCs and acoustic metamaterials.

Theoretical and Experimental Study of Locally Resonant and Bragg Band Gaps in Flexural Beams Carrying Periodic Arrays of Beam-Like Resonators

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Yong Xiao ◽  
Jihong Wen ◽  
Gang Wang ◽  
Xisen Wen
Keyword(s):  
Band Gap ◽  
Coupling Effect ◽  
Numerical Study ◽  
Spectral Element ◽  
Band Gaps ◽  
Local Resonance ◽  
Periodic Arrays ◽  
Finite Structures ◽  
Resonance Frequencies ◽  
Vibration Transmittance

In this paper, we present a design of locally resonant (LR) beams using periodic arrays of beam-like resonators (or beam-like vibration absorbers) attached to a thin homogeneous beam. The main purpose of this work is twofold: (i) providing a theoretical characterization of the proposed LR beams, including the band gap behavior of infinite systems and the vibration transmittance of finite structures, and (ii) providing experimental evidence of the associated band gap properties, especially the coexistence of LR and Bragg band gaps, and their evolution with tuned local resonance. For the first purpose, an analytical method based on the spectral element formulations is presented, and then an in-depth numerical study is performed to examine the band gap effects. In particular, explicit formulas are provided to enable an exact calculation of band gaps and an approximate prediction of band gap edges. For the second purpose, we fabricate several LR beam specimens by mounting 16 equally spaced resonators onto a free-free host beam. These specimens use the same host beam, but the resonance frequencies of the resonators on each beam are different. We further measure the vibration transmittances of these specimens, which give evidence of three interesting band gap phenomena: (i) transition between LR and Bragg band gaps; (ii) near-coupling effect of the local resonance and Bragg scattering; and (iii) resonance frequency of local resonators outside of the LR band gap.

Flexural Vibration Band Gaps in a Ternary Phononic Crystal Thin Plate

2011 ◽  
Vol 675-677 ◽  
pp. 1085-1088
Author(s):  
Zong Jian Yao ◽  
Gui Lan Yu ◽  
Jian Bao Li
Keyword(s):  
Band Gap ◽  
Thin Plate ◽  
Mass Density ◽  
Phononic Crystal ◽  
Flexural Vibration ◽  
Expansion Method ◽  
Band Gaps ◽  
Physical Parameters ◽  
Vibration Band ◽  
Filling Fraction

The band structures of flexural waves in a ternary locally resonant phononic crystal thin plate are studied using the improved plane wave expansion method. And the thin concrete plate composed of a square array of steel cylinders hemmed around by rubber is considered here. Absolute band gaps of flexural vibration with low frequency are shown. The calculation results show that the band gap width is strongly dependent on the filling fraction, the radius ratio, the mass density and the Young’s modulus contrasts between the core and the coating. So by changing these physical parameters, the required band gap could be obtained.

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