Large two-dimensional band gaps in three-component phononic crystals

By using of the plane wave expansion method, we present the large complete elastic wave band gap in the two-dimensional three-component phononic crystals consisting of coating cylinders embedded in a glass host. Based on the localized resonance structure, the optimum gap is obtained by tuning the thickness ratio of the coating layer. The calculations also demonstrate that the acoustic band gaps varied with the filling fraction of the coating cylinders display a different character from the two-component system at the high filling fraction.