镜像对称准周期固/液声子晶体的传输特性

Propagation of elastic wave in the quasi-periodic mirror symmetry phononic crystal composed of solid and liquid

以准周期Fibonacci序列为基础,构建了准周期镜像对称结构的一维固液介质声子晶体。利用转移矩阵法,研究了弹性波在所构建的声子晶体中的透射特性。结果表明:弹性波正入射时,转移矩阵与变介质的特性阻抗有关,由于声子晶体结构的局域失谐,在透射谱的中心频率附近对称出现谐振模;对于Q7序列的声子晶体,带隙内谐振模带宽小于10Hz,能实现超窄带声滤波;弹性波斜入射时,带隙向高频区移动;入射角为5°时,谐振模也向高频移动;入射角为10°时,由于谐振的增强,声子晶体结构对频率的选择性提高,使带隙内的谐振模消失。

On basis of quasi-periodic Fibonacci sequence, the quasi-periodic mirror symmetrical phononic crystals, composed of solids and liquids, are proposed. The transmission of elastic wave in the designed multilayer structure is investigated with transfer matrix method. For elastic wave normal incident, the resonant modes exist in band gap, which are symmetrical in vicinity to central frequency. Consequently, for Q7 sequence, the resonant modes with narrow bandwidth can be acted as super narrow filter. Moreover, for elastic wave oblique incident, the band gap shifts toward the high frequency region. The resonant modes also shift toward the high frequency region for elastic wave at 5°, but the resonant modes disappear in band gap for elastic wave at 10°.