Active vibration control for marine applications

A major problem, in isolating large marine machinery rafts, is how best to mitigate against the effects of excited resonances. These generate large forces on the hull and produce undesirable characteristic signatures. The paper describes the development of a new hybrid active/passive mounting system that has the potential to eradicate such signatures by making use of digitally controlled actuators that ignore local displacements while controlling the response of the structure's rigid body modes. Also described in the paper is a method that has been developed for damping flexural modes of vibration in the receiving structure. This further reduces the levels of vibration by directly tackling the mechanism by which the effect of small forces is amplified. The active damping method has recently been successfully demonstrated on a full-scale vessel and a number of key results obtained in the development process are presented.