Vibroacoustic control of a heavy fluid-loaded plate under turbulent boundary layer excitation using acoustic black hole stiffeners

Stiffened panels are featured in a wide range of engineering applications to provide structural integrity. However, periodic stiffeners can promote Bloch-Floquet wave propagation, which results in increased far-field noise. Moreover, many stiffened structures, such as the hull of a ship or an underwater vehicle and an aircraft fuselage, are subjected to flow-induced vibrations due to the surrounding fluid motion, resulting in additional vibration and noise. This work aims to control the vibroacoustic response of an infinite fluid-loaded stiffened plate under turbulent boundary layer excitation by embedding acoustic black holes into the stiffeners. An efficient semi-analytical method is proposed whereby the necessary flexural and torsional impedances of an acoustic black hole stiffener with a complex geometry are numerically extracted using the finite element method and then coupled with an analytical model of a stochastically excited infinite fluid-loaded plate. The vibroacoustic response of the three-dimensional stiffened plate obtained by the semi-analytical method is verified against a full finite element model. The flow-induced vibroacoustic behaviour of the plate with acoustic black hole stiffeners is then compared against an equivalent case involving rectangular stiffeners as well as with the results from an unstiffened plate.