Low-frequency structural vibration reduction in stiffened panels using integrated acoustic black holes

Stiffened panels are the fundamental elements of ship hulls, composing main structures, such as decks and bulkheads. Due to their key role in hull dynamics, especially in the range of machinery-induced vibrations propagating throughout the structure, reducing their mobility is expected to contribute to an overall decrease in the vessel's acoustic footprint. An emerging technology with high potential for reducing structural vibrations is the Acoustic Black Hole. When integrated into the ship hull, these devices act as energy wells for flexural waves. Over the past two decades, Acoustic Black Holes have been extensively investigated through analytical, numerical, and laboratory-scale experiments. Yet, their practical integration into ship-representative structures remains unexplored. In this paper, two Acoustic Black Holes were integrated into the plating of a mock-up representative of a typical ship stiffened panel. Their placement was defined based on the structural intensity approach; an experimental campaign was conducted to demonstrate the vibration mitigation effect obtained. The results show the suppression of targeted modes and the reduction of vibrational velocity obtained on the stiffened panel plating. This research aims to be the first step towards implementing this technology onboard ships, paving the way for its future application in full-scale marine structures.