Breaking bands degeneracy in two-dimensional hybrid triangular lattice phononic crystal: A theoretical and experimental study

Using symmetry reduction concept, the band gap properties of a two-dimensional hybrid triangular lattice phononic crystal were investigated both theoretically and experimentally. The band structure was calculated with the plane wave expansion (PWE) method. The results revealed that the band degeneracy at high symmetry point in the first Brillouin zone was lifted due to reducing symmetry, and hence a new low-frequency absolute band gap between the first and the second bands appeared. The measured transmission spectra were found to be in good agreement with the numerical results.