Local Resonances of Membrane Arrays in a Phononic Plate Cavity

• Main Authors: Chen-feng Liao, 廖辰峰
• Other Authors: Tsung Tsong Wu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/77778155761936840664

碩士 === 國立臺灣大學 === 應用力學研究所 === 104 === A Phononic crystal (PC) is a kind of structure whose mechanical properties are periodically arranged. The most important character of the phononic crystal is the band gap phenomenon, which means that there is no any wave to propagate in such kind of structure in specific frequency range. If we remove rows of structure in PC, the phononic structure will be a resonator In this thesis, we compute the local resonances membrane arrays in a phononic plate cavity by using the finite element method. The dispersion relation of the membrane was obtained by simulation then we chose the first local resonant mode as a main structure. In order to design the resonator, we compute the dispersion relation of the two-dimensional air/silicon phononic structure, then the first local resonant frequency of the membrane is in the phononic band gap. After that, we used the Rayleigh wave as an energy source, which was generated by two designs of interdigitated electrodes on 128oYX-LiNbO3 substrate. When the Rayleigh wave travels along the surface of the substrate with coupling agent on its path, the energy of the Rayleigh wave will be coupled into the coupling layer as a Rayleigh leaky wave, as a result the membrane arrays will vibrate on the first local resonant mode. In order to optimize the amplitude of the membrane arrays, we discussed the impact of the coupling layer thickness and the effect distance to explore the results of resonant cavity formed by constructive interference. Finally, under the constructive interference there has a significant increase in the amplitude of the resonant cavity and the simulation results can be expected as a micromixer in the future.