Dirac Cone Characteristics of Hexachiral Phononic Crystal

The band structure properties of phononic crystal is important to evaluate the vibration and noise reduction of acoustic metamaterials. Taking the 2D hexachiral phononic crystal as an example, the band structure and Dirac cone properties were investigated by numerical analysis, and the four-fold accidental degenerate Dirac point was obtained in the center of Brillouin zone. By adjusting the design parameters of ligament structure, a double Dirac cone was broken and a novel directional band gap was formed. The influence of geometric parameters on the directional band gaps width was investigated, and the band structure inversion problem was further discussed. This research can provide support for the application of hexachiral phononic crystal in elastic wave manipulation and acoustic topological insulator.