Control of plate vibrations using smart technology

In this paper, the authors describe progress on the development of a hybrid (active/passive) scheme for use in adaptive structures. An aluminium plate is employed as the demonstrator. The technique is based upon the use of a finite element model of the plate, extended to include passive control in the form of viscoelastic and constraining layers. Experimental results are presented to demonstrate the validity of the finite element model of the plate. Onto this framework is superimposed an active control scheme, formulated in modal state space. Emphasis is placed upon model reduction to obtain a low-order controller and to minimise the spillover effects which are induced when such controllers are implemented. Through a series of numerical experiments, it is shown how the presence of passive control introduces damping to improve robustness of modal control strategies. The paper concludes with a discussion of issues which remain to be resolved.