Papers by Keyword: Phononic Crystal

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Authors: Nan Wang, Fu Li Hsiao, Moorthi Palaniapan, Ming Lin Julius Tsai, Jeffrey B.W. Soon, Dim Lee Kwong, Cheng Kuo Lee
Abstract: Two-dimensional (2-D) Silicon phononic crystal (PnC) slab of a square array of cylindrical air holes in a 10μm thick free-standing silicon plate with line defects is characterized as a cavity-mode PnC resonator. Piezoelectric aluminum nitride (AlN) film is deployed as the inter-digital transducers (IDT) to transmit and detect acoustic waves, thus making the whole microfabrication process CMOS-compatible. Both the band structure of the PnC and the transmission spectrum of the proposed PnC resonator are analyzed and optimized using finite element method (FEM). The measured quality factor (Q factor) of the microfabricated PnC resonator is over 1,000 at its resonant frequency of 152.46MHz. The proposed PnC resonator shows promising acoustic resonance characteristics for RF communications and sensing applications.
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Authors: Zhuo Fei Song, Qiang Song Wang, Ya Qiang Tian
Abstract: Studied the ABAC pattern quasiperiodic phononic crystal properties by transfer matrix method, The results show that the frequency of ABAC pattern quasiperiodic phononic crystal initial band gap is lower than AB and AC pattern and the band gap is wider, simultaneously produce strongly localized resonant modes in the first band gap, frequency and quantity of the localized resonant modes are different with different parameters of material C. These properties are useful to the fabrication of the acoustic or elastic wave filters.
544
Authors: Hao Jiang Zhao, Rong Qiang Liu, Hong Wei Guo
Abstract: The improved plane wave expansion method is used to investigate the effects of material parameters on the longitudinal vibration band gaps in thin phononic crystal plates. Both square lattice and graphite lattice are considered. Results show that the parameters playing the essential roles are the mass density ratio and the Young modulus ratio of the scatterers and the host materials.
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Authors: Zong Jian Yao, Gui Lan Yu, Yue Sheng Wang
Abstract: Propagation of flexural vibration in a ternary phononic crystal thin plate with a point defect are explored using finite element method. The thin concrete plate is composed of steel cylinders hemmed around by rubber with a square lattice. Absolute band gaps, point defect bands and transmission response curves with low frequency are investigated. Comparing the results of finite element method with that of improved plane wave expansion method, precise identifications are obtained to identify the point defect states. The results show that the finite element method is suitable for the exploring of flexural vibration propagating in ternary phononic crystal thin plates.
596
Authors: Zong Jian Yao, Gui Lan Yu, Jian Bao Li
Abstract: The band structures of flexural waves in a ternary locally resonant phononic crystal thin plate are studied using the improved plane wave expansion method. And the thin concrete plate composed of a square array of steel cylinders hemmed around by rubber is considered here. Absolute band gaps of flexural vibration with low frequency are shown. The calculation results show that the band gap width is strongly dependent on the filling fraction, the radius ratio, the mass density and the Young’s modulus contrasts between the core and the coating. So by changing these physical parameters, the required band gap could be obtained.
1085
Authors: Zong Jian Yao, Gui Lan Yu, Yue Sheng Wang, Jian Bao Li
Abstract: Based on the finite element method, the propagation of flexural vibration in a binary phononic crystal thick plate with a point defect is studied. The plate is composed of a square array of concrete cylinders embedded in the rubber matrix. Complete band structure and frequency response function of this perfect thick plate indicates the existence of low-frequency absolute band gap. Detailed investigations have been carried out to study the dependence of the width of absolute band gap on both structural and material parameters. For the point defect, the defect modes are localized around the defect, and the frequency and the number of the defect bands are significantly dependent on the filling fraction, the size and the mass density of the defect cylinder. To better support the statement of the defect band structures, we also represent the frequency response function of the propagation of flexural vibration in the thick plate with a point defect. Based on the detailed investigations, both the absolute band gap and the defect bands of a binary thick plate could be modulated with appropriate parameters. It may be useful to vibration control in engineering structure.
1577
Authors: Zong Jian Yao, Gui Lan Yu, Yue Sheng Wang, Jian Bao Li
Abstract: The improved supercell plane wave expansion method is applied to theoretically study the propagation of flexural waves in a ternary locally resonant phononic crystal thin plate with a point defect and linear defects. The thin concrete plate composed of a square array of steel cylinders hemmed around by rubber is considered here. Absolute band gaps in low frequency are obtained. For the point defect, the defect mode is localized around the defect, and the magnitude of the resonant defect mode is strongly dependent on the defect filling fraction, mass density and Young’s modulus of the defect cylinder. For the straight linear defects, several resonant linear defect bands appear inside the absolute band gap. And the displacement distributions show that the flexural waves could well propagate along the linear defects.
1282
Authors: Jiao He, Guang Hui Fan, De Xun Zhao, Ying Kai Liu
Abstract: The band gap of a new two-dimensional phononic crystal was studied by the plane-wave expansion method. The two-dimensional phononic crystal is formed by square-shape array geometry of iron cylinders with square cross section inserted in an epoxy resin. The band gaps of different structures were calculated such as defect-free, single cavity crystal point defect states, crystal point defect states with (10) direction coupling, crystal point defect states with (10) direction next-nearest-neighbor coupling, and crystal point defect states with (11) direction next-nearest-neighbor coupling. Compared with that of defect-free, it is conclude that point defect is beneficial to the production of band gaps. The bandwidth of point defect is about 5 times larger than that of the defect-free crystal with the filling fraction F=0.4. In addition, the maximum number of band gap is in the crystal point defect states with (10) direction next-nearest-neighbor coupling. It will provide a theoretical reference for the manufacture of phononic crystal.
1377
Authors: A Li Chen, Yue Sheng Wang, Chuan Zeng Zhang
Abstract: In this paper, combined with the supercell technique, the plane wave expansion method is used to calculate the band structures of the two-dimensional phononic crystals with line defects and the random disorders in either radius or location of the scatterers. Phononic systems with plumbum scatterers embedded in an epoxy matrix are calculated in detail. The influences of the random disorder on the band structures of anti-plane waveguiding modes will be discussed. The displacement distributions are calculated to show the wave localization phenomenon. Propagation of the guided wave in the phononic crystals with different disordered degree is studied. The analysis is relevant to the assessment of the influences of manufacture errors on wave behaviors in waveguiding phononic crystals as well as the possible control of wave propagation by intentionally introducing disorders into the systems.
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