Vibration damping using a spiral acoustic black hole

Abstract

This study starts from a simple question: can we efficiently reduce the vibration of plates or beams by using a lightweight structure occupying a small space? As an efficient way of damping vibration, we adopted a relatively new concept called Acoustic Black Hole (ABH) with a simple modification of the ABH geometry. The original shape of ABH is a straight wedge-type profile with power-law thickness, and the reduction of vibration in beams or plate increases as the length of ABH increases. However, in real-world applications in the industry, there exists an upper bound of the length of ABH due to the space limitation. Therefore, in this study, authors propose a curvilinear shape of ABH by using a simple mathematical geometry of Archimedean spiral which allows a uniform gap-distance between adjacent baselines of the spiral. We investigated the effect of the curvilinear shape of ABH to the damping performance by comparing the driving point mobility of the conventional straight ABH with the present spiral one. From the simulation, the damping performance increases as the arc length of the Archimedean spiral increases, regardless of the curvature of the spiral. The effect of damping layer attached to ABH is also very influential in enhancing the damping performance while the size and mass of damping layer are very small compared to those of ABH.