scholarly journals the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices

2017 ◽  
Vol 42 (4) ◽  
pp. 725-733 ◽  
Author(s):  
Bo Yuan ◽  
Yong Chen ◽  
Min Jiang ◽  
Shuai Tang ◽  
Miao He ◽  
...  
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional ◽  
Band Gaps ◽  
Acoustic Properties ◽  
Bragg Scattering ◽  
Wavelength Band ◽  
Local Resonance ◽  
Scattering Effects ◽  
Acoustic Speed ◽  
Sub Wavelength

Abstract Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.

Research on local resonance and Bragg scattering coexistence in phononic crystal

2017 ◽  
Vol 31 (11) ◽  
pp. 1750127 ◽  
Author(s):  
Yake Dong ◽  
Hong Yao ◽  
Jun Du ◽  
Jingbo Zhao ◽  
Jiulong Jiang
Keyword(s):  
Band Gap ◽  
Mass Density ◽  
Resonance Effect ◽  
Phononic Crystal ◽  
Broad Band ◽  
Low Frequency ◽  
Bragg Scattering ◽  
Low Frequencies ◽  
Local Resonance ◽  
Resonance Band

Based on the finite element method (FEM), characteristics of the local resonance band gap and the Bragg scattering band gap of two periodically-distributed vibrator structures are studied. Conditions of original anti-resonance generation are theoretically derived. The original anti-resonance effect leads to localization of vibration. Factors which influence original anti-resonance band gap are analyzed. The band gap width and the mass ratio between two vibrators are closely correlated to each other. Results show that the original anti-resonance band gap has few influencing factors. In the locally resonant structure, the Bragg scattering band gap is found. The mass density of the elastic medium and the elasticity modulus have an important impact on the Bragg band gap. The coexistence of the two mechanisms makes the band gap larger. The band gap covered 90% of the low frequencies below 2000 Hz. All in all, the research could provide references for studying the low-frequency and broad band gap of phononic crystal.

Wave Motion in Periodic Flexural Beams and Characterization of the Transition Between Bragg Scattering and Local Resonance

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
Liao Liu ◽  
Mahmoud I. Hussein
Keyword(s):  
Wave Propagation ◽  
Band Structure ◽  
Band Gap ◽  
Frequency Band ◽  
Band Gaps ◽  
Flexural Wave ◽  
Propagation Mechanism ◽  
Bragg Scattering ◽  
Frequency Spectra ◽  
Local Resonance

Band gaps appear in the frequency spectra of periodic materials and structures. In this work we examine flexural wave propagation in beams and investigate the effects of the various types and properties of periodicity on the frequency band structure, especially the location and width of band gaps. We consider periodicities involving the repeated spatial variation of material, geometry, boundary and/or suspended mass along the span of a beam. In our formulation, we implement Bloch’s theorem for elastic wave propagation and utilize Timoshenko beam theory for the kinematical description of the underlying flexural motion. For the calculation of the frequency band structure we use the transfer matrix method, derived here in generalized form to enable separate or combined consideration of the different types of periodicity. Our results provide band-gap maps as a function of the type and properties of periodicity, and as a prime focus we identify and mathematically characterize the condition for the transition between Bragg scattering and local resonance, each being a unique wave propagation mechanism, and show the effects of this transition on the lowest band gap. The analysis presented can be extended to multi-dimensional phononic crystals and acoustic metamaterials.

On the coupling of resonance and Bragg scattering effects in three-dimensional locally resonant sonic materials

Ultrasonics ◽  
2013 ◽  
Vol 53 (7) ◽  
pp. 1332-1343 ◽  
Author(s):  
Bo Yuan ◽  
Victor F. Humphrey ◽  
Jihong Wen ◽  
Xisen Wen
Keyword(s):  
Three Dimensional ◽  
Bragg Scattering ◽  
Scattering Effects

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.

scholarly journals Flexural vibration band gaps for a phononic crystal beam with X-shaped local resonance metadamping structure

2017 ◽  
Vol 66 (14) ◽  
pp. 140701
Author(s):  
Du Chun-Yang ◽  
Yu Dian-Long ◽  
Liu Jiang-Wei ◽  
Wen Ji-Hong
Keyword(s):  
Phononic Crystal ◽  
Flexural Vibration ◽  
Band Gaps ◽  
Vibration Band ◽  
Local Resonance

Band Gaps in Three-Dimensional Layer-by-Layer Phononic Crystal

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
N. Aravantinos-Zafiris ◽  
M. M. Sigalas
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Periodic Boundary ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Periodic Boundary Conditions ◽  
Band Gaps ◽  
Layer By Layer ◽  
Phononic Band Gaps ◽  
Difference Time

In this work, we numerically investigate the existence of phononic band gaps in the layer-by-layer rods structure. For the numerical calculations the finite difference time domain method was used and the transmission, as well as the band structure (using periodic boundary conditions and the Bloch theorem), was calculated. Several different materials (considered as the rods materials) were examined and the effects of all the geometric parameters of the structure were also numerically investigated. The results show that this structure seems to have very promising features as a phononic crystal giving, under certain conditions, a full 3D band gap. Taking into account that it is already known for its use as a photonic crystal, a certain belief for its use simultaneously as a photonic and phononic crystal rises.

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