An experimental study on vibration damping using curvilinear acoustic black holes

Abstract

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. Recently, there was a study on a curved ABH with the baseline of a non-zero curvature using a numerical approach, but the experimental works on the damping performance of the curved ABH are not conducted yet. In this study, we experimentally investigate the effect of curvatures of the curved ABH on the vibration damping performance. The curved ABHs studied in this work are divided into two cases: (1) the curved ABH with the baseline of constant curvatures which has a circular arc shape, (2) the curved ABH with the baseline of varying curvatures. We perform experiments to investigate the effect of constant curvatures on the damping performance of the circular arc shaped ABHs. An Archimedean spiral ABH, a particular form of the curved ABH of slowly varying curvatures is also investigated experimentally. Due to the limitation of machining tolerance, it is difficult to manufacture a perfect spiral ABH whose baseline follows the exact formula. In order to study the effect of manufacturing uncertainty on the damping performance of the spiral ABH, we numerically compare the damping performance of the perfect Archimedean spiral ABH with the incomplete Archimedean spiral ABH which contains abrupt changes in the curvature. The possibility of the spiral ABH as an efficient vibration damping technique is experimentally confirmed.