Band gap properties in two-dimensional phononic crystal slabs with neck structures

Abstract

The numerical investigation on elastic wave band gap properties in two-dimensional phononic crystal slabs composed of periodic cylinders inserted in a homogeneous slab is presented. The cylinders are not connected with the slab directly but linked it through some neck structures constituted by part of an annular cylinder. By using the finite element method, the band structures of the phononic crystal are analyzed and the geometric parameters of the structure are studied for their effects on the band gap properties. Results show that band gaps with low frequencies appear in this structure. The largest band gap can be influenced significantly by the geometric parameters of the neck (including the length, the position, the central angle and the rotation angle of the neck). Furthermore, the vibration eigenmodes of the structure are calculated to reveal the relationship between band gaps and the geometry of the structure. Results show that the occurrence of low frequency band gaps are attributed to the coupling effect of swing modes of cylinders and the plate wave modes of the slab matrix.