Viscoelastic multi-resonator mechanism for broadening low-frequency band-gap of acoustic metamaterials

2019 ◽  
Vol 86 (1) ◽  
pp. 10901 ◽  
Author(s):  
Hongxing Liu ◽  
Jiu Hui Wu
Keyword(s):  
Elastic Modulus ◽  
Band Gap ◽  
Frequency Band ◽  
Loss Modulus ◽  
Great Influence ◽  
Low Frequency ◽  
Band Gaps ◽  
Band Width ◽  
Acoustic Metamaterials ◽  
Practical Applications

In this paper, viscoelastic multi-resonator mechanism for broadening low-frequency band-gaps of acoustic metamaterials is investigated. Firstly, the metamaterial unit consists of dual-mass and dual-viscoelasticity is proposed which can generate multiple resonances to form multiple band-gaps, and further the broadened band-gaps are realized by modulating the effect of the viscoelasticity. Secondly, for the dual-viscoelasticity, the band-gaps and transmission spectrum under the cases of with the consistent and inconsistent viscoelasticity are calculated. Comparing with the consistent case, by adjusting the viscoelasticity in the inconsistent case, the storage modulus changes the fastest and obtains a smaller and a larger elastic modulus at the corresponding starting frequency and ending frequency of the band-gap, in which the band-gap can be broadened and shifted to the low frequency since the resonant frequency is determined by the elastic modulus, and for the loss modulus, it has little effects on the width of the band-gap, but has great influence on the transmission coefficient. Thirdly, by adjusting the inconsistent viscoelastic parameters based on the above rules, the band width is increased by 1.7 times (1.3 times for the absolute band width) than the consistent structure and the band-gap is shifted to the low frequency by 31% (about 345 Hz). The viscoelastic multi-resonator mechanism can be used to practical applications of viscoelastic metamaterials.

scholarly journals Vibration Attenuation Investigations on a Distributed Phononic Crystals Beam for Rubber Concrete Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Chao Li ◽  
Sifeng Zhang ◽  
Liyong Gao ◽  
Wei Huang ◽  
Zhaoxin Liu
Keyword(s):  
Band Gap ◽  
Frequency Band ◽  
High Frequency ◽  
Concrete Beam ◽  
Vibration Isolation ◽  
Civil Engineering ◽  
Low Frequency ◽  
Band Gaps ◽  
Spring Force ◽  
Rubber Concrete

Locally resonant phononic crystals (LRPCs) beam is characterized by the band gaps; some frequency ranges within which flexural waves cannot propagate freely. So, the LRPCs beam can be used for noise or vibration isolation. In this paper, a LRPCs beam with distributed oscillators is proposed, and the general formula of band gaps and transmission spectrum are derived by the transfer matrix method (TMM) and spectrum element method (SEM). Subsequently, the parameter effects on band gaps are investigated in detail. Finally, a rubber concrete beam is designed to demonstrate the application of distributed LRPCs beam in civil engineering. Results reveal that the distributed LRPCs beam has multifrequency band gaps and the number of the band gaps is equal to that of the oscillators. Compared with others, the distributed LRPCs beam can reduce the stress concentration when subjected to vibration. The oscillator interval has no effect on the band gaps, which makes it more convenient to design structures. Individual changes of oscillator mass or stiffness affect the band gap location and width. When the resonance frequency of oscillator is fixed, the starting frequency of the band gap remains constant, and increasing oscillator mass of high-frequency band gap widens the high-frequency band gap, while increasing oscillator mass of low-frequency gap widens both high-frequency and low-frequency band gaps. External loads, such as the common uniform spring force provided by foundation in civil engineering, are conducive to the band gap, and when the spring force increases, all the band gaps are widened. Taken together, a configuration of LRPCs rubber concrete beam is designed, and it shows good isolation on the vibration induced by the railway. By the presented design flow chart, the research can serve as a reference for vibration isolation of LRPCs beams in civil engineering.

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.

Low-frequency and tuning characteristic of band gap in a symmetrical double-sided locally resonant phononic crystal plate with slit structure

2016 ◽  
Vol 30 (27) ◽  
pp. 1650203 ◽  
Author(s):  
X. P. Wang ◽  
P. Jiang ◽  
A. L. Song
Keyword(s):  
Band Gap ◽  
Power Transmission ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Band Gaps ◽  
Geometrical Parameters ◽  
Band Frequency ◽  
Practical Applications ◽  
Tuning Characteristic ◽  
Lower Frequencies

In this paper, the low-frequency and tuning characteristic of band gap in a two-dimensional phononic crystal structure, consisting of a square array of aluminum cylindrical stubs deposited on both sides of a thin rubber plate with slit structure, are investigated. Using the finite element method, the dispersion relationships and power transmission spectra of this structure are calculated. In contrast to a typical phononic crystal without slit structure, the proposed slit structure shows band gaps at lower frequencies. The vibration modes of the band gap edges are analyzed to clarify the mechanism of the lowest band gaps. Additionally, the influence of the slit parameters and stub parameters on the band gaps in slit structure are investigated. The geometrical parameters of the slits and stubs were found to influence the band gaps; this is critical to understand for practical applications. These results will help in fabricating phononic crystal structures whose band frequency can be modulated at lower frequencies.

scholarly journals Composite 3D-printed metastructures for low-frequency and broadband vibration absorption

2016 ◽  
Vol 113 (30) ◽  
pp. 8386-8390 ◽  
Author(s):  
Kathryn H. Matlack ◽  
Anton Bauhofer ◽  
Sebastian Krödel ◽  
Antonio Palermo ◽  
Chiara Daraio
Keyword(s):  
Band Gap ◽  
Low Frequency ◽  
Band Gaps ◽  
Acoustic Metamaterials ◽  
Structural Vibrations ◽  
Band Gap Engineering ◽  
Vibration Absorption ◽  
Shock Mitigation ◽  
Lattice Geometry ◽  
3D Printed

Architected materials that control elastic wave propagation are essential in vibration mitigation and sound attenuation. Phononic crystals and acoustic metamaterials use band-gap engineering to forbid certain frequencies from propagating through a material. However, existing solutions are limited in the low-frequency regimes and in their bandwidth of operation because they require impractical sizes and masses. Here, we present a class of materials (labeled elastic metastructures) that supports the formation of wide and low-frequency band gaps, while simultaneously reducing their global mass. To achieve these properties, the metastructures combine local resonances with structural modes of a periodic architected lattice. Whereas the band gaps in these metastructures are induced by Bragg scattering mechanisms, their key feature is that the band-gap size and frequency range can be controlled and broadened through local resonances, which are linked to changes in the lattice geometry. We demonstrate these principles experimentally, using advanced additive manufacturing methods, and inform our designs using finite-element simulations. This design strategy has a broad range of applications, including control of structural vibrations, noise, and shock mitigation.

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.

Multi-large low-frequency band gaps in a periodic hybrid structure

2016 ◽  
Vol 30 (08) ◽  
pp. 1650116 ◽  
Author(s):  
T. Wang ◽  
M. P. Sheng ◽  
H. B. Guo
Keyword(s):  
Frequency Band ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Hybrid Structure ◽  
Band Gaps ◽  
Response Analysis ◽  
Acoustic Metamaterials ◽  
Frequency Range ◽  
Local Resonance ◽  
Small Series

A hybrid structure composed of a local resonance mass and an external oscillator is proposed in this paper for restraining the elastic longitudinal wave propagation. Theoretical model has been established to investigate the dispersion relation and band gaps of the structure. The results show that the hybrid structure can produce multi-band gaps wider than the multi-resonator acoustic metamaterials. It is much easier for the hybrid structure to yield wide and low band gaps by adjusting the mass and stiffness of the external oscillator. Small series spring constant ratio results in low-frequency band gaps, in which the external oscillator acts as a resonator and replaces the original local resonator to hold the band gaps in low frequency range. Compared with the one-dimensional phononic crystal (PC) lattice, a new band gap emerges in lower frequency range in the hybrid structure because of the added local resonance, which will be a significant assistance in low-frequency vibration and noise reduction. Further, harmonic response analysis using finite element method (FEM) has been performed, and results show that elastic longitudinal waves are efficiently forbidden within the band gaps.

scholarly journals Locally Resonant Phononic Crystals at Low frequencies Based on Porous SiC Multilayer

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ahmed Mehaney ◽  
Ashour M. Ahmed
Keyword(s):  
Band Gap ◽  
Frequency Band ◽  
Acoustic Waves ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Band Gaps ◽  
Resonance Phenomenon ◽  
Porous Sic ◽  
Phononic Band Gaps ◽  
Sound Suppression

Abstract In this work, a one-dimensional porous silicon carbide phononic crystal (1D-PSiC PnC) sandwiched between two rubber layers is introduced to obtain low frequency band gaps for the audible frequencies. The novelty of the proposed multilayer 1D-PnCs arises from the coupling between the soft rubber, unique mechanical properties of porous SiC materials and the local resonance phenomenon. The proposed structure could be considered as a 1D acoustic Metamaterial with a size smaller than the relevant 1D-PnC structures for the same frequencies. To the best of our knowledge, it is the first time to use PSiC materials in a 1D PnC structure for the problem of low frequency phononic band gaps. Also, the porosities and thicknesses of the PSiC layers were chosen to obtain the fundamental band gaps within the bandwidth of the acoustic transducers and sound suppression devices. The transmission spectrum of acoustic waves is calculated by using the transfer matrix method (TMM). The results revealed that surprising low band gaps appeared in the transmission spectra of the 1D-PSiC PnC at the audible range, which are lower than the expected ones by Bragg’s scattering theory. The frequency at the center of the first band gap was at the value 7957 Hz, which is 118 times smaller than the relevant frequency of other 1D structures with the same thickness. A comparison between the phononic band gaps of binary and ternary 1D-PSiC PnC structures sandwiched between two rubber layers at the micro-scale was performed and discussed. Also, the band gap frequency is controlled by varying the layers porosity, number and the thickness of each layer. The simulated results are promising in many applications such as low frequency band gaps, sound suppression devices, switches and filters.

Band-Gap Properties of Elastic Metamaterials With Inerter-Based Dynamic Vibration Absorbers

2018 ◽  
Vol 85 (7) ◽  
Author(s):  
Xiang Fang ◽  
Kuo-Chih Chuang ◽  
Xiaoling Jin ◽  
Zhilong Huang
Keyword(s):  
Band Gap ◽  
Frequency Band ◽  
Low Frequency ◽  
Lattice System ◽  
Band Gaps ◽  
Vibration Absorbers ◽  
Dynamic Vibration ◽  
Elastic Metamaterials ◽  
Dynamic Vibration Absorbers ◽  
Mass Spring

In this paper, inerter-based dynamic vibration absorbers (IDVAs) are applied in elastic metamaterials to broaden low-frequency band gaps. A discrete mass-spring lattice system and a distributed metamaterial beam carrying a periodic array of IDVAs are, respectively, considered. The IDVA consists of a spring and an inerter connected to a traditional mass-spring resonator. Compared to the traditional resonators, the special designed IDVAs generate two local-resonance (LR) band gaps for the discrete lattice system, a narrow low-frequency band gap and a wider high-frequency one. For the distributed IDVA-based metamaterial beam, in addition to the generated two separated LR band gaps, the Bragg band gap can also be significantly broadened and the three band gaps are very close to each other. Being able to amplify inertia, the IDVAs can be relatively light even operated for opening up low-frequency band gaps. When further introducing a dissipative damping mechanism into the IDVA-based metamaterials, the two close-split LR band gaps in the lattice system are merged into one wide band gap. As for the metamaterial beam with the dissipative IDVAs, an even wider band gap can be acquired due to the overlap of the adjacent LR and Bragg-scattering band gaps.

Experimental Study of the Transmission Spectrum of a Sonic/Ultrasonic Acoustic Metamaterial

2016 ◽  
Author(s):  
Yanbo He ◽  
Jeffrey S. Vipperman
Keyword(s):  
Band Gap ◽  
Frequency Band ◽  
Transmission Spectrum ◽  
Physical Phenomenon ◽  
Experimental Studies ◽  
Low Frequency ◽  
Acoustic Metamaterials ◽  
Acoustic Metamaterial ◽  
Potential Applications ◽  
Lower Frequency Band

Acoustic metamaterials have received much attention recently. In the past decades, countless structures have been studied for their novel physical phenomenon or potential applications. The goals of many of the works were to explore ways to enlarge the band gap, lower the band gap frequency, and/or generate greater attenuation of vibration. However, most of the work was limited to simulation, with experimental studies rarer. In this work, we would like to experimentally present the transmission spectrum of an acoustic metamaterial with a proposed structure called the coated double hybrid lattice (CDHL) [1]. The CDHL has both crystalline structure and local resonators, which provide high-frequency and low-frequency band gaps, respectively. A structure was fabricated and tested to experimentally determine the transmission spectrum. Both, a higher frequency band gap and a lower frequency band gap, were obtained. Vibration is clearly attenuated in the frequency range of 70–90 kHz. This is due to the Bragg scattering effect. At the same time, around the frequency of 4.8kHz, another band gap is observed which is attributed to local resonance. It turns out that our experimental results coincide with our previous simulation quite well.

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