Analysis of Vibration and Acoustic Coupling of Plates with Acoustic Black Holes Using Wavenumber Transforms

Acoustic Black Holes (ABHs) have been developed in recent years as an effective way to reduce the mechanical vibration and radiation sound power of panels while also reducing the weight of the panel. ABHs use a gradual change in the plate thickness to decrease the bending wave speed and increase the transverse vibration amplitude. Vibrational energy can then be effectively dissipated through high strain energy in high loss materials. These materials can either be the ABH material itself or an attached damping layer. In this paper, measured velocity responses of plates with and without embedded ABHs were transformed into wavenumber space to investigate the usefulness of wavenumber transforms for ABH characterization and design. The results showed that wavenumber spectra offer new ways of analyzing ABH behavior that are not available through other kinds of experimental analysis. The wavenumber spectra were also used to investigate the structural acoustic coupling and radiation efficiency of the plates. The results showed that ABHs can make supersonic waves subsonic, thereby reducing the radiated sound in addition to reducing the mechanical vibration. The results will be useful for the characterization, design, and optimization of real ABH systems.