A Two-Way Unidirectional Narrow-Band Acoustic Filter Realized by a Graded Phononic Crystal

2017 ◽  
Vol 84 (9) ◽  
Author(s):  
Yingjie Chen ◽  
Yang Huang ◽  
Chaofeng Lü ◽  
Weiqiu Chen
Keyword(s):  
Band Gap ◽  
Narrow Band ◽  
Phononic Crystal ◽  
Close Relation ◽  
Propagation Characteristic ◽  
Pass Band ◽  
Heterogeneous Structure ◽  
Resonant Frequencies ◽  
Propagation Behavior ◽  
Periodic Components

Unidirectional acoustic transmission is acquired in a one-dimensional graded phononic crystal. The distinct feature of the present design is that waves can propagate unidirectionally at a certain frequency from the left to right, and waves at another frequency can propagate in the opposite direction from the right to left. This two-way asymmetric propagation behavior is realized at the narrow resonant frequencies in the acoustic band gap by a novel mechanism, which is totally linear and obeys the time-reversal symmetry. Simulation shows that for the graded heterogeneous structure, the resonant peaks of frequency in the acoustic band gap for opposite propagation directions become different. In the transmission spectrum, this mechanism corresponds to a pass-band splitting, and each separated peak represents a unidirectional propagation behavior. The separation of two peaks has been proved to have a close relation to the grading degree of the material property in the spatially periodic components. The unique propagation characteristic obtained at resonant frequencies in the band gaps may provide us a new way to realize a two-way unidirectional narrow-band acoustic filter.

Propagation of Lamb Waves in Phononic-Crystal Plates

2007 ◽  
Vol 23 (3) ◽  
pp. 223-228 ◽  
Author(s):  
J.-C. Hsu ◽  
T.-T. Wu
Keyword(s):  
Band Gap ◽  
Triangular Lattice ◽  
Lamb Waves ◽  
Phononic Crystal ◽  
Plate Thickness ◽  
Expansion Method ◽  
Band Gaps ◽  
Square Lattice ◽  
Pass Band ◽  
Band Structures

AbstractIn this paper, the band structures of Lamb waves in the two-dimensional phononic-crystal plates are calculated and analyzed based on the plane wave expansion method. The phononic-crystal plates are composed of an array of circular crystalline iron cylinders embedded in the epoxy matrix. Square lattice and triangular lattice are analyzed and discussed, respectively. For the square lattice, two complete band gaps exist, and a narrow pass band between the complete band gaps separates them apart. For the triangular lattice, a wide complete band gap existing with the ratio of gap width to midgap frequency Δω/ωm equal to 72% is found. Furthermore, the influence of the plate thickness is crucial for band structures of Lamb waves. Tuning plate thickness can shift the pass bands effectively, and band shifting causes the variation of the width of complete band gap and its opening and closure.

Coupling between two kinds of band gaps of a shunted tube piezoelectric phononic crystal

2017 ◽  
Vol 28 (16) ◽  
pp. 2153-2166 ◽  
Author(s):  
Ziyang Lian ◽  
Hongping Hu ◽  
Longxiang Dai ◽  
Yuxing Liang ◽  
Bin Luo ◽  
...  
Keyword(s):  
Band Gap ◽  
Phononic Crystal ◽  
Band Gaps ◽  
Double Layers ◽  
Pass Band ◽  
Bragg Scattering ◽  
Coupling Region ◽  
Electromagnetic Oscillation ◽  
Crystal Model ◽  
Short Circuits

A tube-type piezoelectric phononic crystal model is proposed to study interaction between locally resonant and Bragg band gaps, which is arrayed periodically by metal and piezoelectric segments. Each piezoelectric segment consists of a shell with series-connected and opposite directions polarized double layers and a resonant shunting circuit. According to the interaction between Bragg scattering and local electromagnetic oscillation, three regions corresponding to the inductance can be divided as follows: quasi-short circuits region, coupling region, and quasi-open circuits region. Some interesting phenomena are found from the coupling between Bragg scattering and locally resonant of electromagnetic oscillation. (1) In the coupling region, a pass band splits a Bragg band gap into two band gaps. But the cut-off frequency of the second band gap does not change with the inductance. (2) In the quasi-open circuits region, Bragg and locally resonant band gaps exist independently. (3) The first band gap transits from Bragg scattering to local resonance when the inductance increases from quasi-short circuits region to quasi-open circuits region. (4) The cut-off frequency of the first band gap is always less than the estimated resonant frequency of inductor-capacitor oscillators. Finally, the theoretical result is validated by two kinds of finite element models based on ANSYS.

Search of Phononic Crystal Band-Gap about the Array of 2D Square Tube with Slits

2014 ◽  
Vol 536-537 ◽  
pp. 1481-1485
Author(s):  
Long Gen Li ◽  
Yong Gang Chen
Keyword(s):  
Band Gap ◽  
Acoustic Waves ◽  
Structural Parameters ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Propagation Characteristic ◽  
Steel Tube ◽  
The Finite Element Method ◽  
Transmission Coefficients ◽  
Square Array

A band structure composed of a square array of parallel steel tube with narrow slits is presented.The propagation characteristic of acoustic waves in this structure is investigated theoretically by the finite element method. In particular the acoustic-solid coupling is taken into account for accurate results. The transmission coefficients of the band system with different angles of the square tubes and slits width are calculated. A large continuous band gap at a low frequency range in a compound structure is obtained due to the interaction of peaks and gaps fordifferent Structural parameters.

scholarly journals Tunable Low Frequency Band Gap and Waveguide of Phononic Crystal Plates with Different Filling Ratio

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 828
Author(s):  
Shaobo Zhang ◽  
Jiang Liu ◽  
Hongbo Zhang ◽  
Shuliang Wang
Keyword(s):  
Band Gap ◽  
Composite Structure ◽  
Structural Parameters ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Filling Ratio ◽  
Height Ratio ◽  
Road Vehicles ◽  
Aluminum Base ◽  
Gap Width

Aiming at solving the NVH problem in vehicles, a novel composite structure is proposed. The new structure uses a hollow-stub phononic-crystal with filled cylinders (HPFC) plate. Any unit in the plate consists of a lead head, a silicon rubber body, an aluminum base as outer column and an opposite arranged inner pole. The dispersion curves are investigated by numerical simulations and the influences of structural parameters are discussed, including traditional hollow radius, thickness, height ratio, and the new proposed filling ratio. Three new arrays are created and their spectrum maps are calculated. In the dispersion simulation results, new branches are observed. The new branches would move towards lower frequency zone and the band gap width enlarges as the filling ratio decreases. The transmission spectrum results show that the new design can realize three different multiplexing arrays for waveguides and also extend the locally resonant sonic band gap. In summary, the proposed HPFC structure could meet the requirement for noise guiding and filtering. Compared to a traditional phononic crystal plate, this new composite structure may be more suitable for noise reduction in rail or road vehicles.

scholarly journals Influence of surface band bending on a narrow band gap semiconductor: Tunneling atomic force studies of graphite with Bernal and rhombohedral stacking orders

2021 ◽  
Vol 5 (4) ◽  
Author(s):  
Regina Ariskina ◽  
Michael Schnedler ◽  
Pablo D. Esquinazi ◽  
Ana Champi ◽  
Markus Stiller ◽  
...  
Keyword(s):  
Band Gap ◽  
Narrow Band ◽  
Surface Band ◽  
Band Bending ◽  
Atomic Force
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