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Abstract: Based
on the vibrational equation of the one- dimensional thin rod phononic
crystals composed of two kind of material, the vibrational wave and
surface wave implicit dispersion relation in periodically layered
infinite and semi- infinite media are provided. The width of band gaps
and surface wave frequency both relate with the material portion ratio.
For the phononic crystals with a free surface, the necessary condition
for the existence of the surface localized modes in the free surface is
found to be the velocity of the material with free surface less than
that of the other material. Using the finite element method, the
vibrational frequency response of finite- size phononic crystals and
found the particular resonance peak due to the surface localized modes
in the band gaps is calculated. These resonance peaks decreae the
frequency response attenuation at least 20 dB.
Key
words: Phononic
crystals Vibration band gap Surface localized modes
CLC No: O321
TH113 O48
国家973重大基础研究资助项目(51307). Received
20040623, received in revised form 20041110 |