ACOUSTIC BLACK HOLES: GEOMETRICAL GENERALIZATION TO EXPERIMENTAL VALIDATION

摘要

Acoustic black hole (ABH) is a wedge-shaped structure with a power law profile attached to one end of a plate or beam to dampen the bending waves from the plate or beam, thereby reducing the vibration. The original geometrical shape of an ABH has a straight baseline, and the reduction of vibration in beams or plates increasing as the length of the ABH increases. However, in real-world applications, there exists an upper bound of the length of an ABH due to space limitations. Therefore, in this study, the authors propose a curvilinear geometry of ABH using the simple mathematical geometry of an Archimedean spiral, which allows a uniform gap distance between adjacent baselines of the spiral. In numerical simulations, the damping performance increases as the spiral length of the Archimedean spiral increases regardless of the curvature of the spiral in the mid- and high-frequency ranges. Adding the damping material to the ABH could strongly enhance the damping performance while not significantly increasing the weight. In addition, the authors experimentally investigate the effect of curvatures of the curved ABH on the vibration damping performance for the purpose of practical application to real-world problem with compact-sized ABH.