Band Structure Research of a 2D Honeycomb Lattice Phononic Crystal

Using ultrasonic immersion transmission technique, the band gap properties of a two-dimensional honeycomb lattice/water 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 crystals exist low frequency band gap and the frequency range of the first compete band gap is accordance with the theoretical calculation. The band degeneracy at high symmetry point in the first Brillouin zone was lifted due to increase Filling Fraction, and hence a new low-frequency absolute band gap between the first and the second bands appeared. With the normalization radii(r(0)/a) increase that the first band gap relative broadband of the honeycomb array of steel cylinders in water is monotonic increase and open band gap in (r(0)/a) = 0.21. The measured transmission spectra were found to be in good agreement with the numerical results.