The band gap characteristic of a double-leaf acoustic black hole coupled with rotatable local resonance structure

In traditional acoustic black hole (ABH), the band gap (BG) is limited by its structural dimensions, so it can only occur at relatively high frequencies. Meanwhile, the BG is usually presented only in one direction. For solving the dual problems of broadband and multi-directional vibration suppression, this paper proposes a double-leaf ABH coupled with adjustable rotatable local resonance structure. By combining the local resonance effect and the Bragg scattering effect, the scheme generates five BGs spanning low to high frequencies in two orthogonal directions. Based on the design scheme, four angles were selected to introduce the influence of the rotation angle of the local resonance structure on the BGs. The results show that different rotation angles change the overall structural stiffness, and thus affect the generation of BGs. Meanwhile, generalization to arbitrary in-plane directions is left for future work.