Acoustic wave frequency filtering in constant total length phononic crystals of Al/Pb multilayer

Author(s):  
Chittaranjan Nayak ◽  
Mehdi Solaimani ◽  
Alireza Aghajamali ◽  
Arafa H. Aly

In this study, we have scrutinized the frequency gap generation by changing the geometrical parameters of a one-dimensional phononic crystal. For this purpose, we have calculated the transmission coefficient of an incident acoustic wave by using the transfer matrix method. We have retained and fixed the total length of the system and changed the system internal geometry not to increase the system length too much. Another reason was to adjust the phononic band gaps and get the desired transmission properties by finding the optimum internal geometry without increasing or decreasing the total length of phononic crystals. In addition, we also propose few structures with the opportunity of applications in acoustical devices such as sonic reflectors. Our results can also be of high interest to design acoustic filters in the case that transmission of certain frequencies is necessary.

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1485
Author(s):  
Fei Ge ◽  
Liye Zhao ◽  
Yang Zhang

Surface acoustic wave gyroscopes (SAWGs), as a kind of all-solid-state micro-electro-mechanical system (MEMS) gyroscopes, can work normally under extremely high-impact environmental conditions. Among the current SAWGs, amplitude-modulated gyroscopes (AMGs) are all based on the same gyro effect, which was proved weak, and their sensitivity and intensity of the output are both lower than frequency-modulated gyroscopes (FMGs). However, because FMGs need to process a series of frequency signals, their signal processing and circuits are far less straightforward and simple than AMGs. In order to own both high-sensitivity and simple signal processing, a novel surface acoustic traveling wave gyroscope based on amplitude modulation is proposed, using one-dimensional phononic crystals (PCs) in this paper. In view of its specific structure, the proposed gyroscope consists of a surface acoustic wave oscillator and a surface acoustic wave delay line within a one-dimensional phononic crystal with a high-Q defect mode. In this paper, the working principle is analyzed theoretically through the partial wave method (PWM), and the gyroscopes with different numbers of PCs are also designed and studied by using the finite element method (FEM) and multiphysics simulation. The research results demonstrate that under a 1 V oscillator voltage output, the higher sensitivity of −23.1 mV·(rad/s)−1 in the linear range from −8 rad/s to 8 rad/s is reached when the gyro with three PC walls, and the wider linear range from −15 rad/s to 17.5 rad/s with the sensitivity of −6.7 mV·(rad/s)−1 with only one PC wall. Compared with the existing AMGs using metal dots to enhance the gyro effect, the sensitivity of the proposed gyro is increased by 15 to 112 times, and the linear range is increased by 4.6 to 186 times, even without the enhancement of the metal dots.


2019 ◽  
Vol 26 (02) ◽  
pp. 1850144 ◽  
Author(s):  
ARAFA H. ALY ◽  
AHMED NAGATY ◽  
Z. KHALIFA

We have theoretically obtained the transmittance properties of one-dimensional phononic crystals incorporating a piezoelectric material as a defect layer. We have used the transfer matrix method in our analysis with/without defect materials. By increasing the thickness of the defect layer, we obtained a sharp peak created within the bandgap, that indicates to the significance of defect layer thickness on the band structure. The localized modes and a particular intensity estimated within the bandgap depend on the piezoelectric material properties. By applying different quantities of an external electric field, the position of the peak shifts to different frequencies. The electric field induces a relative change in the piezoelectric thickness. Our structure may be very useful in some applications such as sensors, acoustic switches, and energy applications.


2021 ◽  
Vol 12 (1) ◽  
pp. 167
Author(s):  
Hongbo Zhang ◽  
Shaobo Zhang ◽  
Jiang Liu ◽  
Bilong Liu

Weyl physics in acoustic and elastic systems has drawn extensive attention. In this paper, Weyl points of shear horizontal guided waves are realized by one-dimensional phononic crystal plates, in which one physical dimension plus two geometrical parameters constitute a synthetic three-dimensional space. Based on the finite element method, we have not only observed the synthetic Weyl points but also explored the Weyl interface states and the reflection phase vortices, which have further proved the topological phase interface states. As the first realization of three-dimensional topological phases through one-dimensional phononic crystal plates in the synthetic dimension, this research demonstrates the great potential of applicable one-dimensional plate structural systems in detecting higher-dimensional topological phenomena.


Author(s):  
Xinya Zhang ◽  
Ted Jackson ◽  
Emmanuel Lafound ◽  
Pierre Deymier ◽  
Jerome Vasseur

Novel phononic crystal structures on thin plates for material science applications in ultrasonic range (~ MHz) are described. Phononic crystals are created by a periodic arrangement of two or more materials displaying a strong contrast in their elastic properties and density. Because of the artificial periodic elastic structures of phononic crystals, there can exist frequency ranges in which waves cannot propagate, giving rise to phononic band gaps which are analogous to photonic band gaps for electromagnetic waves in the well-documented photonic crystals. In the past decades, the phononic structures and acoustic band gaps based on bulk materials have been researched in length. However few investigations have been performed on phononic structures on thin plates to form surface acoustic wave band gaps. In this presentation, we report a new approach: patterning two dimensional membranes to form phononic crystals, searching for specific acoustic transport properties and surface acoustic waves band gaps through a series of deliberate designs and experimental characterizations. The proposed phononic crystals are numerically simulated through a three-dimensional plane wave expansion (PWE) method and experimentally characterized by a laser ultrasonics instrument that has been developed in our laboratory.


2009 ◽  
Vol 1188 ◽  
Author(s):  
Albert C To ◽  
Bong Jae Lee

AbstractThe present study demonstrates that interfacial acoustic waves can be excited at the interface between two phononic crystals. The interfacial wave existing between two phononic crystals is the counterpart of the surface electromagnetic wave existing between two photonic crystals. While past works on phononic crystals exploit the unique bandgap phenomenon in periodic structures, the present work employs the Bloch wave in the stop band to excite interfacial waves that propagate along the interface and decay away from the interface. As a result, the proposed structure can be used as a wave filter as well as a thermal barrier. In wave filter design, for instance, the incident mechanical wave energy can be guided by the interfacial wave to the lateral direction; thus, its propagation into the depth is inhibited. Similarly, in thermal barrier design, incident phonons can be coupled with the interfacial acoustic wave, and the heat will be localized and eventually dissipated at the interface between two phononic crystals. Consequently, the thermal conductivity in the direction normal to the layers can be greatly reduced. The advantage of using two phononic crystals is that the interfacial wave can be excited even at normal incidence, which is critical in many engineering applications. Since the proposed concept is based on a one-dimensional periodic structure, the analysis, design, and fabrication are relatively simple compared to other higher dimensional material designs.


Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1130
Author(s):  
Jiacheng Liu ◽  
Temesgen Bailie Workie ◽  
Ting Wu ◽  
Zhaohui Wu ◽  
Keyuan Gong ◽  
...  

Thin-film piezoelectric-on-silicon (TPoS) microelectromechanical (MEMS) resonators are required to have high Q-factor to offer satisfactory results in their application areas, such as oscillator, filter, and sensors. This paper proposed a phononic crystal (PnC)-reflector composite structure to improve the Q factor of TPoS resonators. A one-dimensional phononic crystal is designed and deployed on the tether aiming to suppress the acoustic leakage loss as the acoustic wave with frequency in the range of the PnC is not able to propagate through it, and a reflector is fixed on the anchoring boundaries to reflect the acoustic wave that lefts from the effect of the PnC. Several 10 MHz TPoS resonators are fabricated and tested from which the Q-factor of the proposed 10 MHz TPoS resonator which has PnC-reflector composite structure on the tether and anchoring boundaries achieved offers a loaded Q-factor of 4682 which is about a threefold improvement compared to that of the conventional resonator which is about 1570.


2017 ◽  
Vol 09 (07) ◽  
pp. 1750102 ◽  
Author(s):  
Yuhang Li ◽  
Xiaoliang Zhou ◽  
Zuguang Bian ◽  
Yufeng Xing ◽  
Jizhou Song

Phononic crystal is an artificial periodic structure with the ability to regulate and control the wave propagation of particular frequencies and has been widely used in many applications. The adhesive layer bonding different constituents in the periodic structure of phononic crystals is usually a viscoelastic material, which has frequency-dependent material properties. In this paper, an analytical model based on the transfer matrix method is developed to study the bandgap structures of SH-wave (a shear wave with the propagation direction normal to the motion plane) in a one-dimensional phononic crystal consisting of two different elastic constituents bonded by the viscoelastic adhesive layer. The results show that the viscosity of the adhesive layer has a significant influence on the bandgap structure at the region of high frequency. The effects of various material parameters of the viscoelastic adhesive layer such as the relaxation time, the final-state modulus and the initial-state modulus are systematically studied. These results are very helpful in the practical design of phononic crystals involving the viscoelastic adhesive layers.


2011 ◽  
Vol 287-290 ◽  
pp. 650-653
Author(s):  
Zhuo Fei Song ◽  
Qiang Song Wang ◽  
Zi Dong Wang

Comprehensive study is performed for the one-dimensional phononic crystals with locally resonant structures mechanism and Bragg scattering mechanism. Found locally resonant mechanism is same as Bragg scattering mechanism on one-dimension phononic crystal. The reasons of producing lower frequency band gap are still stiffness decrease and quality increase. So the theory that locally resonant structure is better than Bragg scattering in low frequency vibration reduction is inexact.


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