Study on Filling Fraction of Bandgap Lowest Starting Frequency of one Dimension Phononic Crystals

2012 ◽  
Vol 518-523 ◽  
pp. 3865-3868
Author(s):  
Zhuo Fei Song ◽  
Qiang Song Wang ◽  
Zai Qiang Feng ◽  
Zi Dong Wang

A calculation method of lowest band gap starting frequency corresponding to filling fraction of fixed periodic size one dimension phononic crystals are given, found the filling fraction only correlation with the density of two materials, but no correlation with elastic modulus, furthermore found no correlation with periodic size.

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Rixin Cui ◽  
Jinsong Zhou ◽  
Dao Gong

The prevention of environmental vibration pollution induced by train operation is one of the inevitable problems in the construction of urban rail transit. With the advantage of flexible adjustment, phononic crystals (PCs) have a broad application prospect in suppressing elastic wave propagation of rail transit. In this paper, a damped rail with two-dimensional honeycomb PCs was proposed, and its band structure was analysed with FEM. Then, a parametric study was used to investigate the influences of design parameters of the honeycomb PCs on its band gap property. Furthermore, with a 3D half-track model, the vibration reduction property of the damped rail with honeycomb PCs was discussed. The results show that the damped rail with honeycomb PCs has an absolute band gap in the frequency range of 877.3–1501.7 Hz, which includes the pinned-pinned resonance frequency of the rail internally. Reducing the filling fraction and elastic modulus of the matrix can obtain an absolute band gap in a lower frequency range but also bring a narrower bandwidth. The decrease of scatterer density leads to higher boundary frequencies of the absolute band gap and descends the bandwidth. In order to obtain an absolute band gap which can suppress the pinned-pinned resonance of the rail and keep a wider bandwidth, the filling fraction is suitable to be about 0.5, and the elastic modulus of the matrix is proposed to be not more than 0.6 MPa. Metals with heavy density can be used as the scatterer to obtain a better vibration reduction effect. It is hoped that the research results can provide a reference for the application of PCs in track vibration reduction.


Author(s):  
Saeed Mohammadi ◽  
Abdelkrim Khelif ◽  
Ryan Westafer ◽  
Eric Massey ◽  
William D. Hunt ◽  
...  

Periodic elastic structures, called phononic crystals, show interesting frequency domain characteristics that can greatly influence the performance of acoustic and ultrasonic devices for several applications. Phononic crystals are acoustic counterparts of the extensively-investigated photonic crystals that are made by varying material properties periodically. Here we demonstrate the existence of phononic band-gaps for surface acoustic waves (SAWs) in a half-space of two dimensional phononic crystals consisting of hexagonal (honeycomb) arrangement of air cylinders in a crystalline Silicon background with low filling fraction. A theoretical calculation of band structure for bulk wave using finite element method is also achieved and shows that there is no complete phononic band gap in the case of the low filling fraction. Fabrication of the holes in Silicon is done by optical lithography and deep Silicon dry etching. In the experimental characterization, we have used slanted finger interdigitated transducers deposited on a thin layer of Zinc oxide (sputtered on top of the phononic crystal structure to excite elastic surface waves in Silicon) to cover a wide range of frequencies. We believe this to be the first reported demonstration of phononic band-gap for SAWs in a hexagonal lattice phononic crystal at such a high frequency.


Author(s):  
Yi-Ze Wang ◽  
Kazuaki Inaba ◽  
Feng-Ming Li ◽  
Kikuo Kishimoto

The viscous effects on the band gap characteristics of the piezoelectric/viscous liquid phononic crystals are studied. The expressions of the generalized eigenvalue equation for the cylindrical phononic crystals are derived. Numerical calculations are performed to discuss the band gap characteristics with different filling ratios and viscous damping parameters. Form the results, it can be observed that the out-of-plane mode will appear, which caused by the viscous effects. Both of the real and imaginary parts of frequencies will increase with the filling fraction becoming larger. The maximum of the normalized band gap width is achieved by f = 0.5. Furthermore, the band gap edges become higher with the viscous damping parameter increasing, especially for higher band gaps.


2014 ◽  
Vol 113 (21) ◽  
Author(s):  
D. Yudistira ◽  
A. Boes ◽  
B. Djafari-Rouhani ◽  
Y. Pennec ◽  
L. Y. Yeo ◽  
...  

2019 ◽  
Vol 13 ◽  
pp. 102200 ◽  
Author(s):  
Yingjian Sun ◽  
Yingjie Yu ◽  
Yayu Zuo ◽  
Lili Qiu ◽  
Mingming Dong ◽  
...  

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