Experimental realization of lower-frequency complete band gaps in 2D phononic crystals

The lattice configurations are used to produce the different effects of band gap. Based on the well-known ultrasonic immersion transmission technique, the experimental investigation of acoustic wave propagation in two-dimensional phononic crystals for square, honeycomb and (4.82) lattices of steel rods in water is reported at the same normalized radius. Using the plane-wave expansion method we calculate the band structures of phononic crystal. The configurations of square, honeycomb and (4.82) lattices have an atom-rods, two atoms-rods and four atoms-rods per unit cell respectively. We found the structure of (4.82) lattice can have the advantage over other lattice structures and open the very lower-frequency complete band gap. Also, a good agreement between experimental results of complete band gaps for three lattices phononic crystals and theoretical predictions is obtained. Thus, the (4.82) phononic crystal may help to design the new controlling materials in lower-frequency ranges as noise barriers.