Topological interface state and vibration localization of acoustic black hole dual-beam structures

The acoustic black hole (ABH) structure creates an effective isolation zone between the vibration source and the sensitive area by employing a gradient material or an elastic structure. This approach significantly reduces vibration and noise, making it promising for applications in construction and mechanical engineering. In this work, three types of the ABH dual-beam structures are designed, and the topological states and vibration localization phenomena in these structures are analyzed. A theoretical model is established using the transfer matrix method (TMM), and the finite element method (FEM) is used to examine the bandgap variation in the ABH dual-beam structures. The topological state is validated by analyzing the vibration modes at the bandgap boundaries. Further investigation on the topological structures reveals that the frequency response curves exhibit isolated peaks within the bandgap. Transverse vibration is focused at the junction interface, as shown by the vibration modes found at the isolated peaks, exhibiting the distinctive energy localization behavior linked to the topological interface state. Adjusting the structural design can enhance the concentration of vibration energy. This work proposes a novel design method for the ABH dual-beam structures to improve the vibration energy concentration effect.