PIEZOELECTRIC MATERIAL AND ONE-DIMENSIONAL PHONONIC CRYSTAL

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.

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.


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.


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.


2011 ◽  
Vol 211-212 ◽  
pp. 609-614 ◽  
Author(s):  
Qi Hua Wen

By deducing the spherical elastic wave equation in theory, the concept of sphere-radial phononic crystal is proposed, and then the equations to determine the acoustic band structures is deduced. A numerical example is given for steel/nitrile rubber phononic crystal. The numerical simulation results suggest that the band gaps of sphere-radial phononic crystals do exist, which have better attenuation characteristics and practical application performance than the one-dimensional phononic crystals.


2013 ◽  
Vol 81 (4) ◽  
Author(s):  
Zuguang Bian ◽  
Wei Peng ◽  
Jizhou Song

Phononic crystals make the realization of complete acoustic band gaps possible, which suggests many applications such as vibration isolation, noise suppression, acoustic barriers, filters, wave guides, and transducers. In this paper, an analytic model, based on the transfer matrix method, is developed to study the band structures of bulk acoustic waves including SH-, P-, and SV-waves in a one-dimensional phononic crystal, which is formed by alternating strips of two different materials. The analysis is demonstrated by the phononic crystal of Ba0.7Sr0.3TiO3 (BST) and polybutylene terephthalate (PBT), whose elastic properties depend strongly on the temperature. The results show that some band gaps are very sensitive to the temperature. Depending on the wave mode, the center frequency of the first band gap may decrease over 25% and band gap width may decrease over 60% as the temperature increases from 30 °C to 50 °C. The transmission of acoustic waves in a finite phononic crystal is also studied through the coefficient of transmission power. These results are very useful for the design and optimization of thermal tuning of phononic crystals.


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