Directional Bandgap Analysis in Phononic Crystal with Rectangular Super Cell Structure

Abstract

Phononic crystals have promising applications in the field of elastic waves and to attenuate the vibrations with their extraordinary feature of stop bands also known as bandgaps. Due to periodicity in structure, the wave in certain band of frequencies is not allowed to propagate. In this paper, we have proposed a phononic crystal whose unit cell is composed of super cell structure consisting of air voids and scatterer distributed in nice rectangular units. The new design is found to have a wider directional band gap in the low-frequency zone. The dispersion relationship of the model is obtained by the computational method using finite element analysis. Numerical results show that the improved phononic crystal with super cell structure enhances the directional bandgap by around 180% when compared with the conventional phononic crystal having one scatterer with same filling factor. The proposed model with super cell structure opens the directional bandgap of 84 Hz with the lower bound frequency of 125Hz and upper bound frequency of 209 Hz in the horizontal (Γ→X) direction.