LOW-FREQENCY BAND GAPS IN A DOUBLE-SIDED STUBBED COMPOSITE PC PLATE

In this paper, the band structures of lamb wave in a double-sided composite PC plate composed of a square array of cylindrical stubs on both sides of a 2D binary locally resonant PC plate is studied. The dispersion relationships and the displacement fields of the eigenmodes are calculated by FEM. Numerical results show that, in this structure, the band gaps will shift to lower frequencies and more band gaps appear compared with the classic double-sided stubbed PC plate and the one-sided stubbed composite PC plate. The evolution of band gaps in the double-sided stubbed composite PC plate with stub height on both side arranged from an asymmetrical distribution to a symmetrical distribution gradually is investigated to illustrate these phenomenon. The displacement fields of the eigenmodes are calculated to further illustrate the opening mechanism of the band gaps in lower frequencies. Furthermore, the effects of geometric parameters on the band gaps are investigated. Results show that the band gaps can be modulated in an relatively lower and larger frequency range by the geometric parameters such as the stub diameter and plate thickness. These acoustic properties in the proposed PC plate can potentially be applied to optimize band gaps and produce lower-frequency filters and waveguides.