Study on Topological Transport Effect of Two-dimensional Core-shell Cylindrical Phononic Crystals

In recent years, the topologically protected boundary state transmission in phononic crystals has become an emerging research field. This paper proposes a two-dimensional core-shell cylindrical phononic crystal, which introduces two independent degrees of freedom in the unit cell geometry by adjusting the center offset distance and offset angle of the steel cylinder. By changing the degrees of freedom, the symmetry of time reversal can be broken, and the topological properties of the band structure can be adjusted. Therefore, a topological protection system is established in the reconfigurable phononic crystal, which can be turned on and off only by changing the offset distance and the offset angle of the cylinder center, realizing the unidirectional transmission of edge states. This topological transport effect is bound to be beneficial to the design of tunable, efficient, and multifunctional acoustic devices, and will be widely used in the fields of electronics, telecommunications, and acoustic imaging.