The multi-bandgap of local effect phononic crystal

Abstract

A design method of a phononic crystal structure with a local effect is introduced, and the mechanism and influencing factors (elastic modulus, density, local layer thickness) of the bandgap are analyzed. The finite element method is used to calculate the eigenfrequency. The first bandgap width accounts for more than 98% of the frequency below 20 000 Hz. Two kinds of materials with different wave velocities are arranged periodically to form a two-dimensional local effect structure. Due to the influence of the local effect, when the elastic wave propagates in the local layer, the wave propagation will be restrained, and the eigenfrequency spectrum presents a series of discrete energy levels. The material parameters and structural parameters of the transmission layer have a great influence on the bandgap. The first bandgap is an ultra-wide low frequency bandgap, and the bandgap frequency ranges from 238 to 18857 Hz. This periodic structure with the local effect has great potential application value in noise and vibration suppression.