Flexural vibration band gaps in a double-side phononic crystal plate

Using the finite element method, we theoretically study the vibration properties of a phononic crystal plate composed of a square array of composite cylindrical pillars on both sides of a thin homogeneous plate. The dispersion relations, the displacement fields of the eigenmodes, and the power transmission spectra are given to estimate the starting and cutoff frequency of the flexural vibration band gaps. We investigate the evolution of the flexural vibration band gaps in the double-side phononic crystal plate, with the height and diameter of the pillars on both sides arranged from a symmetrical distribution to an asymmetrical distribution. Numerical results show that the enlargement of the bandwidth of flexural vibration band gaps in both symmetrical and asymmetrical double-side phononic crystal plates depends strongly on the rise of the cutoff frequency of the gaps. The two pillars with an asymmetrical heights or diameters divide the first flexural vibration band gap into two gaps. These propagation properties of flexural vibration in the double-side plate can be utilized to design low-frequency vibration insulation and band-pass filters.