Configurations of ring-shaped acoustic black holes for the isolation of vibrations in plates

In many common situations concerning the vibroacoustics of built-up structures, a plate gets excited at a limited region where it is connected to further structural elements, like beams or other supporting elements. To avoid the transmission of vibrations to the plate one would typically resort to elastic junctions. However, that is not always feasible and, even if it was, they may not provide enough isolation. It is proposed herein to increase the latter by resorting to ring-shaped ABH configurations consisting in, at least, one annular strip with a power-law decaying profile in the radial direction. The ring-shaped ABH strip is used to surround the external excitation area and prevent the transmission of vibrations to the rest of the plate. Designs including radial stiffeners are also presented to avoid excessive structural weakening. The numerical simulations carried out using a Rayleigh-Ritz approach with a Gaussian expansion for the flexural displacement field, show that the ring-shaped ABH constitute an efficient way to enhance vibration isolation in plates.