Low-frequency spatial wave manipulation via phononic crystals with relaxed cell symmetry

2014 ◽  
Vol 115 (10) ◽  
pp. 103502 ◽  
Author(s):  
Paolo Celli ◽  
Stefano Gonella
Keyword(s):  
Low Frequency ◽  
Phononic Crystals ◽  
Cell Symmetry

Low frequency phononic band structures in two-dimensional arc-shaped phononic crystals

2012 ◽  
Vol 376 (33) ◽  
pp. 2256-2263 ◽  
Author(s):  
Zhenlong Xu ◽  
Fugen Wu ◽  
Zhongning Guo
Keyword(s):  
Low Frequency ◽  
Phononic Crystals ◽  
Two Dimensional ◽  
Band Structures

scholarly journals Phononic Band Gaps of Elastic Periodic Structures: A Homogenization Theory Study

2007 ◽  
Author(s):  
Ying-Hong Liu ◽  
Chien C. Chang ◽  
Ruey-Lin Chern ◽  
C. Chung Chang
Keyword(s):  
Elastic Constants ◽  
Periodic Structures ◽  
Mass Density ◽  
Density Ratio ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Homogenization Theory ◽  
Dominant Factor ◽  
Phononic Band Gaps

In this study, we investigate band structures of phononic crystals with particular emphasis on the effects of the mass density ratio and of the contrast of elastic constants. The phononic crystals consist of arrays of different media embedded in a rubber or epoxy. It is shown that the density ratio rather than the contrast of elastic constants is the dominant factor that opens up phononic band gaps. The physical background of this observation is explained by applying the theory of homogenization to investigate the group velocities of the low-frequency bands at the center of symmetry Γ.

Topological Interface States in the Low-Frequency Band Gap of One-Dimensional Phononic Crystals

2020 ◽  
Vol 14 (5) ◽  
Author(s):  
Zheng-wei Li ◽  
Xin-sheng Fang ◽  
Bin Liang ◽  
Yong Li ◽  
Jian-chun Cheng
Keyword(s):  
Band Gap ◽  
Frequency Band ◽  
Low Frequency ◽  
Interface States ◽  
Phononic Crystals ◽  
One Dimensional

scholarly journals Design and Experimental Validation of a Metacomposite Made of an Array of Piezopatches Shunted on Negative Capacitance Circuits for Vibroacoustic Control

2013 ◽  
Author(s):  
F. Tateo ◽  
M. Collet ◽  
M. Ouisse ◽  
M. N. Ichchou ◽  
K. A. Cunefare
Keyword(s):  
New Technologies ◽  
Control Method ◽  
Low Frequency ◽  
Elastic Solid ◽  
Numerical Approach ◽  
Anomalous Behavior ◽  
Phononic Crystals ◽  
Underlying Structure ◽  
Negative Capacitance ◽  
New Class

In the last few decades, researchers have given a lot of attention to new engineered materials with the purpose of developing new technologies and devices such as mechanical filters, low frequency sound and vibration isolators, and acoustic waveguides. For instance, elastic phononic crystals may come to mind. They are materials with elastic or fluid inclusions inside a matrix made of an elastic solid. The anomalous behavior in phononic crystals arises from interference of waves propagating within an inhomogeneous material. The inclusions inside the matrix cause strong modifications of scattering properties. However, the application of phononic crystals is still limited to sonic frequencies. In fact, band gaps can be generated only when the acoustic wavelength is comparable to the distance between the inclusion. In order to overcome this limitation, a new class of metamaterial has been proposed: meta composite. This new class of material can modify the dynamics of the underlying structure using a bidimensional array of electromechanical transducers, which are composed by piezo patches connected to a synthetic negative capacitance. In this study, an application of the Floquet-Bloch theorem for vibroacoustic power flow optimization will be presented. In the context of periodically distributed, damped 2D mechanical systems, this numerical approach allows one to compute the multimodal waves dispersion curves into the entire first Brillouin zone. This approach also permits optimization of the piezoelectric shunting electrical impedance, which controls energy diffusion into the proposed semiactive distributed set of cells. Experiments performed on the examined structure illustrates the effectiveness of the proposed control method. The experiment requires a rectangular metallic plate equipped with seventyfive piezopatches, controlled independently by electronic circuits. More specifically, the out-of-plane displacements and the averaged kinetic energy of the controlled plate are compared in two different cases (control system on/off). The resulting data clearly show how this proposed technique is able to dampen and selectively reflect the incident waves.

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.

Bandgap Properties of Two-Layered Locally Resonant Phononic Crystals

2020 ◽  
Vol 12 (07) ◽  
pp. 2050075
Author(s):  
Hongyun Wang ◽  
Heow Pueh Lee ◽  
Wei Xu
Keyword(s):  
Coating Thickness ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Formation Mechanisms ◽  
Frequency Range ◽  
The Third ◽  
Resonance Frequencies ◽  
Rubber Coating ◽  
Lower Frequency Range ◽  
Mass Spring

Multi-layered locally resonant phononic crystals (LRPCs) with wider and multiple bandgaps (BGs) in low frequency range and small size of the unit cell have promising applications in noise and vibration controls. In this paper, a 2D two-layered ternary LRPC consisting of a periodical array of cylindrical inclusions embedded in an epoxy matrix is investigated by the finite element method (FEM), where the inclusion is comprised of two coaxial cylindrical steel cores with rubber coating. It is found that the size of the inclusion of the 2D two-layered ternary LRPC has significant effects on the BG properties. With the increase of the core radius and coating thickness, the first BG would shift to lower frequency range with its width decreasing, and the second BG width would become wider until the third BG appears. Especially, with the increase of the coating thickness, more bands and BGs would appear in the lower frequency range. Based on the formation mechanisms of the BGs, several mass-spring models to predict the frequencies of the first two BG edges are developed. The results calculated by these mass-spring models are in good agreement with those by the FEM except for the upper edge frequency of the second BG when the rubber coating thickness exceeds a certain value and the third BG is opened up. These proposed mass-spring models would allow for quick pre-estimation of the resonance frequencies, and facilitate the selection of possible parameters for the wider and lower frequency BGs to obtain the desired attenuation bands. The studies would also benefit the design of multiple BGs for some device applications.

Multilayer-split-tube resonators with low-frequency band gaps in phononic crystals

2014 ◽  
Vol 116 (10) ◽  
pp. 103514 ◽  
Author(s):  
Li Jing ◽  
Jiu Hui Wu ◽  
Dong Guan ◽  
Nansha Gao
Keyword(s):  
Frequency Band ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Band Gaps

LOCALIZED MODES OF A COMPRESSION WAVE IN TWO-DIMENSIONAL SOLID–SOLID PHONONIC CRYSTALS

2012 ◽  
Vol 26 (29) ◽  
pp. 1250189 ◽  
Author(s):  
ZHENLONG XU ◽  
FUGEN WU ◽  
ZHONGNING GUO
Keyword(s):  
Low Frequency ◽  
Expansion Method ◽  
Phononic Crystals ◽  
P Wave ◽  
Wave Band ◽  
Two Dimensional ◽  
Plane Wave Expansion Method ◽  
Localized Modes ◽  
Potential Applications ◽  
Localization Of Vibration

We have studied the compression (P) wave band structures at a low frequency in two-dimensional solid–solid phononic crystals. The plane-wave expansion method based on the decomposition of elastic waves was used. The pressure field distribution of P-wave localized modes at Γ points in the lowest bands, including multiple flat bands of systems comprising different configurations, were analyzed. The results show that a lower symmetry of the scatterer are an effective method to enhance the localization of vibration modes. The property has potential applications in the design of waveguides.

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