On the Study of Local Resonances in Two Dimensional Phononic Crystals with Composite Fillers
Date Issued
2005
Date
2005
Author(s)
Wu, Yi-Chen
DOI
zh-TW
Abstract
In this thesis, the sonic band gap properties of a two-dimensional periodic three-component composite are investigated. The three-component phononic crystal consists of rubber-coated lead cylinders embedded in an epoxy matrix. The FDTD method was employed to calculate the dispersion and transmission to identify acoustic gaps of three-component phononic crystals. Conventional two-component phononic crystals are not suitable to be applied to block audible and low frequency acoustic waves because of their bulkiness and high cost in applications. However, analysis of the three-component phononic crystal shows a different property to overcome the limitation. From the transmittance spectra and the dispersion relation of the in-plane mode, we see that drop in transmission coefficient corresponding to the frequency in the dispersion curve where group velocity is equal to zero. As a result, there are gaps due to resonant mechanisms in the sonic crystals. Nevertheless, not all local resonances in such phononic crystal can cause decay in the energy transmission coefficient. Therefore, by analyzing the vibrational mode of single wavenumber in unit cell under different resonant frequency, we find that unit cell with greater sum of displacement vector can cause a decay in low frequency elastic wave. Further analysis show that by varying the number of layers, geometric size, and arrangement of the phononic crystals, which consists of lead core and silicone rubber, we can control the resonance frequency and transmission coefficient of resonance type phononic crystal.
Subjects
聲子晶體
頻溝現象
局部共振
隔音設備
Phononic crystals
Band gap
Local resonance
Sound insulation
Type
thesis
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