Attenuation Coefficients Prediction for Reflection Layers of Solidly Mounted Resonators via Phononic Band Structures

2008 ◽  
Author(s):  
Chien-Hou Liu ◽  
Yuan-Fang Chou
Keyword(s):  
Band Gap ◽  
Attenuation Coefficient ◽  
Periodic Structures ◽  
Characteristic Impedance ◽  
Phononic Crystal ◽  
Stop Band ◽  
Density Ratio ◽  
Phononic Crystals ◽  
Band Structures ◽  
Attenuation Coefficients

The solidly mounted resonator (SMR) is one of the major focuses in filter research because it can be used in the frequency above GHz range. The reflection structure composed of periodic layers is vital to the performance of this type of resonator due to its capability in confining acoustic energy in the piezoelectric layer. Therefore the design of reflection layers is a key issue in the development of SMRs. The performance of reflection layers is revealed by the attenuation coefficient that governs the energy distribution in the periodic structures. The behavior of waves propagate in the finite periodic structures are solved by transfer matrix method while the Hill’s method is employed to find the exact solutions in the corresponding phononic crystal. By comparing their displacement fields, it is observed that the attenuation coefficients of infinite and finite periodic structures are almost identical provided the number of layers is adequate. Therefore referring the design of reflection layers to the band structures of the corresponding phononic crystals is reasonable although the attenuation coefficient of a finite periodic structure can not be calculated directly. For one dimensional phononic crystals, the attenuation coefficient becomes larger as the first band gap gets wider. Moreover, the characteristic impedance ratio and density ratio between two interlaced materials increase simultaneously; the first band gap width also increases. This character can be adopted as a guideline in the design of solidly mounted resonators. Based on this guideline, Al and W are chosen as materials for the reflection structure. By calculating its electric impedance, the resonant frequency is found to be the same as the center frequency of first band gap of the corresponding phononic crystal. It shows that employing this stop band character to design the reflection structure of SMR is adequate and efficient.

Thermal Tuning of Band Structures in a One-Dimensional Phononic Crystal

2013 ◽  
Vol 81 (4) ◽  
Author(s):  
Zuguang Bian ◽  
Wei Peng ◽  
Jizhou Song
Keyword(s):  
Band Gap ◽  
Acoustic Waves ◽  
Vibration Isolation ◽  
Phononic Crystal ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Polybutylene Terephthalate ◽  
Band Structures ◽  
One Dimensional ◽  
Thermal Tuning

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.

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.

Full Band-Gap Silicon Phononic Crystals for Surface Acoustic Waves

2006 ◽  
Author(s):  
Saeed Mohammadi ◽  
Abdelkrim Khelif ◽  
Ryan Westafer ◽  
Eric Massey ◽  
William D. Hunt ◽  
...  
Keyword(s):  
Band Gap ◽  
Acoustic Waves ◽  
Phononic Crystal ◽  
Surface Acoustic Waves ◽  
Hexagonal Lattice ◽  
Phononic Crystals ◽  
Bulk Wave ◽  
Filling Fraction ◽  
Phononic Band Gap ◽  
Wide Range

Periodic elastic structures, called phononic crystals, show interesting frequency domain characteristics that can greatly influence the performance of acoustic and ultrasonic devices for several applications. Phononic crystals are acoustic counterparts of the extensively-investigated photonic crystals that are made by varying material properties periodically. Here we demonstrate the existence of phononic band-gaps for surface acoustic waves (SAWs) in a half-space of two dimensional phononic crystals consisting of hexagonal (honeycomb) arrangement of air cylinders in a crystalline Silicon background with low filling fraction. A theoretical calculation of band structure for bulk wave using finite element method is also achieved and shows that there is no complete phononic band gap in the case of the low filling fraction. Fabrication of the holes in Silicon is done by optical lithography and deep Silicon dry etching. In the experimental characterization, we have used slanted finger interdigitated transducers deposited on a thin layer of Zinc oxide (sputtered on top of the phononic crystal structure to excite elastic surface waves in Silicon) to cover a wide range of frequencies. We believe this to be the first reported demonstration of phononic band-gap for SAWs in a hexagonal lattice phononic crystal at such a high frequency.

Reactively-loaded non-periodic slow-wave artificial transmission lines for stop band bandwidth enhancement: application to power splitters

2019 ◽  
Vol 11 (5-6) ◽  
pp. 475-481 ◽  
Author(s):  
Jan Coromina ◽  
Paris Vélez ◽  
Jordi Bonache ◽  
Francisco Aznar-Ballesta ◽  
Armando Fernández-Prieto ◽  
...  
Keyword(s):  
Slow Wave ◽  
Transmission Lines ◽  
Periodic Structures ◽  
Characteristic Impedance ◽  
Stop Band ◽  
Pass Band ◽  
Harmonic Suppression ◽  
Transmission Zeros ◽  
Rejection Level ◽  
Power Splitters

AbstractThis paper presents slow-wave transmission lines based on non-periodic reactive loading. Specifically, the loading elements are stepped impedance shunt stubs (SISS). By sacrificing periodicity using SISS tuned to different frequencies, multiple transmission zeros above the pass band arise, and the rejection level and bandwidth of the stop band is improved as compared with those of periodic structures. Through a proper design, it is possible to achieve compact lines, simultaneously providing the required electrical length and characteristic impedance at the design frequency (dictated by specifications), and efficiently filtering the response at higher frequencies. These lines are applied to the design of a compact power splitter with filtering capability in this work. The length of the splitter, based on a 35.35 Ω impedance inverter, is reduced by a factor of roughly two. Moreover, harmonic suppression better than 20 dB up to the fourth harmonic is achieved.

Elastic Wave Propagation in a Bio-Inspired Phononic Crystal

2020 ◽  
Vol 1012 ◽  
pp. 9-13
Author(s):  
H.V. Cantanhêde ◽  
E.J.P. Miranda Jr. ◽  
J.M.C. dos Santos
Keyword(s):  
Wave Propagation ◽  
Band Structure ◽  
Vibrational Energy ◽  
Periodic Structures ◽  
Chemical Elements ◽  
Phononic Crystal ◽  
Stop Band ◽  
Elastic Vibration ◽  
Band Gaps ◽  
Sound Waves

The wave propagation in a two-dimensional bio-inspired phononic crystal (PC) is analysed. When composite materials and structures consist of two or more different materials periodically, there will be stop band characteristic, in which there are no mechanical propagating waves. These periodic structures are known as PCs. PCs have shown an excellent potential in many disciplines of science and technology in the last decade. They have generated lots of interests due to their ability to manipulate mechanical waves like sound waves and thermal properties which are not available in nature. The physical properties of PCs are not essentially determined by chemical elements and bonds in the materials, but rather on the internal specific structures. Structures of this type have the ability to inhibit the propagation of vibrational energy over certain ranges of frequencies forming band gaps. The main purpose of this study is to investigate the band structure and especially the location and width of band gaps. For this analysis, it is used the finite element method (FEM) and plane wave expansion (PWE). The results are shown in the form of band structure and wave modes. Band structures calculated by FEM and PWE present good agreement. We suggest that the bio-inspired PC considered should be feasible for elastic vibration control.

Multifunctional One-dimensional Phononic Crystal Structures Exploiting Interfacial Acoustic Waves

2009 ◽  
Vol 1188 ◽  
Author(s):  
Albert C To ◽  
Bong Jae Lee
Keyword(s):  
Acoustic Waves ◽  
Filter Design ◽  
Phononic Crystal ◽  
Stop Band ◽  
Phononic Crystals ◽  
Thermal Barrier ◽  
Interfacial Wave ◽  
Lateral Direction ◽  
One Dimensional ◽  
Wave Filter

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.

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.

Application of phononic crystals for vibration reduction and noise reduction of wheel-driven electric buses based on neural networks

2021 ◽  
pp. 095440702110359
Author(s):  
Boqiang Zhang ◽  
Penghui Chen ◽  
Huiyong Chen ◽  
Tianpei Feng ◽  
Chengxin Cai ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Band Gap ◽  
Structural Parameters ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
System A ◽  
Electric Bus

Because of the position of the motor and the excitation of the suspension system, a wheel-driven electric bus produces low-frequency noise, which is difficult to resolve through traditional sound absorption and noise reduction technology. Through an interior noise test of a wheel-driven electric bus, we found that the interior low-frequency noise had a considerable influence on the driver. In order to solve this problem, a locally resonant phononic crystal was used to meet the requirements of vibration and noise reduction for the wheel-driven electric bus. The intrinsic relationship between the band gap distribution of the locally resonant phononic crystal and the topology was established by training a neural network, so as to achieve the desired effect of the bandgap model on the basis of the input bandgap range. Upon an increase in the number of models, the prediction model error decreased gradually. This method could quickly obtain the structural parameters of the locally resonant phononic crystal with the expected band gap, which made it convenient to apply locally resonant phononic crystals to the vibration and noise reduction of wheel-driven electric buses and in other fields.

scholarly journals Optical, IR and THz screens based on layered metal-dielectric-semiconductor structures

2019 ◽  
Vol 43 (5) ◽  
pp. 765-772 ◽  
Author(s):  
M.V. Davidovich ◽  
I.A. Kornev
Keyword(s):  
Band Gap ◽  
Narrow Band ◽  
Periodic Structures ◽  
Multilayer Coatings ◽  
Lorentz Model ◽  
Band Structures ◽  
Semiconductor Structures ◽  
Transparent Substrate ◽  
Approximate Synthesis ◽  
The Difference

In this work, we consider multilayer coatings of metal-dielectric-semiconductor nanosized layers located on a transparent substrate and described on the basis of the Drude–Lorentz model that serve as multiband screen filters for different frequency ranges. Structures with several layers and quasi-periodic structures are investigated. A method of the approximate synthesis of band gap structures with two layers per period and three layers per period is proposed. For three layers, the difference in plasma frequencies allows one to extend the bands. It is shown that semiconductor layers made of narrow-band crystal materials like InSb are promising for THz-band structures with the ability to adjust the ranges by doping.

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