Acoustic wave propagation of tunable two-dimensional phononic crystal
Date Issued
2011
Date
2011
Author(s)
Tsai, Chen-Che
Abstract
Many dispersion characteristics of phononic crystal are investigated. Such as negative refraction have become hot topics of scientific research in recent years.
The arrayed arrangement tunable dispersion characteristics of phononic crystals are observed. By controlling the arrayed arrangement, we can tune the refractive direction and adjust the location of focus and then the tunable acoustic superlens can be designed.
There has been much research into the collimation of light source beams by photonic crystals. However, this effect has seldom been achieved using phononic crystals (PCs). On the other hand, it has been shown that acoustic waves may be collimated by resonant cavities in 2D PCs to obtain high directivity. We focuses on the collimation of an acoustic point source by negative refraction in 2D PCs. The advantages of this method are: experiment apparatus is uncomplicated; the divergence angle is only about 5° in the far region; and it has low attenuation when propagating energy.
And we also combine three different form 2D PCs become a multilayered PCs to obtain wide frequency bandwidth(20Hz~20kHz) effect. In this method, we can reduce noise which people can hear.
It is anticipated that this collimating beam method and multilayered PCs may be applied in 2D and 3D acoustic assembled devices or in ultrasonic and sonar detection devices.
Subjects
phononic crystal
filling ratio
collimating acoustic wave beam
negative refraction
resonant cavity
band gap
Type
thesis
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