Research on wave bandgaps in a circular plate of radial phononic crystal

Two alternating homogeneous materials are periodically introduced along the radial direction, forming a circular plate of radial phononic crystal (CPRPC). To illustrate the characteristics of the out-of-plane transverse wave and the in-plane longitudinal wave propagating along the radial direction, the transfer matrices are derived based on the basic wave equations of a thin circular plate in cylindrical coordinates. Localization factors are introduced to evaluate the average attenuation of the transverse and longitudinal waves in the structure, and corresponding bandgaps are obtained. Moreover, finite element method simulations, numerical analyses and the insertion loss method are combined to investigate the effects of the main parameters on these wave bandgaps. The results show that significant transverse and longitudinal wave bandgaps caused by the radial periodicity of the CPRPC exist, and the structural and material parameters have essential influences on them.