Experimental study on vibration damping using curvilinear acoustic black hole

Abstract

Acoustic black hole (ABH) is a wedge-shaped structure of a power law, which is attached to one end of the plate/beam to attenuate the bending wave for damping vibration. Recently, compact and lightweight Archimedean spiral ABH has been proposed and its damping performance has been studied by numerical simulation. However, the vibration damping performance of spiral ABH predicted in the previous numerical study have not yet been validated experimentally which is important for practical application of spiral ABH to vibration induced real-world problem. In this paper, we experimentally validate the two effects, i.e. curvature effect and length effect, predicted in the previous numerical study. ABH is classified into a standard ABH with a zero curvature and curvilinear ABH with non-zero curvature. The curvilinear ABH is divided into a circular arc ABH with constant curvature and a spiral ABH with varying curvature. Manufacturing of curvilinear ABH is a difficult considering the thin tip, power-law profile, and spiral shape. Three manufacturing methods are investigated to manufacture the accurate spiral ABH. Among them, WEDM was chosen for manufacturing the spiral ABH because of its extremely high precision of machining. We experimentally validated the effect of curvature on vibration damping performance using arc ABHs of different curvatures. The effect of ABH length on the damping performance is investigated through experiment using the spiral ABHs of different lengths. We also study the effect of the damping material attached to the tip region and the gap distance between the spiral lines on the damping performance. Finally, we investigated the damping performance asymmetric dual ABH that two ABH of different length is attached to both sides of a beam.