Low‐Frequency Flexural Wave Focusing and Collimation Control Using Periodic Defect‐Based Acoustic Black Hole Plates

Traditional acoustic black hole (ABH) structures have been primarily utilized for vibration reduction and noise suppression. However, research on the manipulation of flexural waves using ABH structures remains limited. In contrast, although phononic crystals exhibit excellent wave control capabilities, they often require complex designs involving multiple material combinations and typically need to be immersed in water to achieve effective wave manipulation. Their ability to directly control wave propagation within solid structures is therefore restricted. Herein, inspired by the periodic theory of phononic crystals, a periodic defect‐type ABH structure composed of a single material is proposed and its ability to manipulate flexural waves is systematically investigated. The propagation mechanisms are analyzed through the solution of evanescent waves and out‐of‐plane dispersion characteristics using the Partial Differential Equation (PDE) method, combined with studies of equifrequency contours maps, group velocity, and phase velocity. Based on this theoretical analysis, numerical simulations are conducted to verify the actual flexural wave manipulation effects. The results demonstrate that the proposed structure can achieve negative refraction, focusing, and collimated propagation of flexural waves within a homogeneous solid, revealing excellent wave control capabilities and promising application potential.