Band structures of 2-D sonic crystals with square lattices based finite element method

Sonic crystals are composite materials made of periodic distributions of inclusions embedded in a matrix. Due to the periodicity, these materials may exhibit complete acoustic band gaps within which sound and vibrations are forbidden. In this paper, the band gap characteristics of a 2-D square array of hollow cylinders and spit-ring hollow cylinders embedded in air are investigated by COMSOL® finite element method, and then verified by plane wave expansion method. The results are very consistent, proving that COMSOL® can be employed for the full characterization of the structures.