In this paper, a tunable metamaterial consisting of periodic layers of steel, polyurea and piezoelectric ceramic transducer
(PZT) was presented. The PZT layer in this structure was connected to an inductor L. Transfer matrix method was used
to calculate the band structure of the sample. It was observed that an extremely narrow stop band was induced by the
PZT layer with inductor L. This narrow stop band was attributed to the resonance circuit constituted by the piezoelectric
layer, for the piezoelectric layer with electrodes could be seen as a capacitor. Further, homogenization was used to
calculate the effective elastic constants of the sample. Results showed that the effective parameters of this structure
behaved negative in the narrow stop band. The location of the narrow stop band was in the charge of inductor L, which
could be used to design acoustic filters or noise insulators by changing the parameters of structure.
|