Acoustic Black Hole vibration mitigation on a ship deck structure using superelement modeling

Vibration and noise have been persistent issues affecting the marine sector since the introduction of mechanised propulsion. Several countermeasures were introduced, including engine resilient mounts, suspended floors, and viscoelastic materials. However, these solutions often fail or are ineffective at low frequencies (below 100 Hz). A new solution, Acoustic Black Holes, showed good potential in mitigating structural vibrations on ships. In the present context, they consist of tapered beams that absorb the vibrational energy carried by flexural waves through the hull. The extent of the application needed to observe Acoustic Black Hole effects on the vibration of a large structure, such as a ship deck, is significant. The finite element method is suitable for this purpose; however, the mesh required to well-discretise these devices is incompatible with the typical meshes used for studying huge commercial ships. In this paper, the Craig-Bampton theory of element condensation was used to model an Acoustic Black Hole as a dynamic superelement. The superelement was first validated on the finite element model of a stiffened panel. Subsequently, a series of Acoustic Black Holes was incorporated into a large hull model representing a portion of a ship's deck. This analysis represents the first step toward implementing Acoustic Black Holes as an alternative to current damping solutions for marine structures.