Lightweight damping layer with acoustic black hole profile bonded to a beam for broadband vibration reduction

Abstract

Inspired by the thickness reduction and wave focusing characteristics of the acoustic black hole (ABH) effect, a so-called ABH-damping layer (ABHD) is proposed for the broadband vibration reduction of a host structure, different from the common-used uniform thickness damping layer (UNID). The ABHD has a lighter weight and shows better vibration suppression ability. It can overcome the defect that ABHs cannot serve as the main load-bearing component due to the stiffness reduction. The primary beam structure and damping layer both follow the Timoshenko beam theory. The null space method handles the continuity between the two-layer structures. Analyses reveal the difference in vibration suppression characteristics between UNID and ABHD, further exhibiting the wave-gathering properties of ABH. The mass reduction ratio of ABHs is presented under different damping material loss factors. Finally, an experiment is conducted to verify the correctness of the proposed method and the feasibility of designing the ABHD. The damping layer’s weight of ABHD is reduced by 30.8% less than that of UNID, when the material loss factor is equal to 1.0. This study provides a new method for lightweight, strong vibration suppression performance and wide-band vibration reduction in engineering with the application of ABH.