Model-based control of plate vibrations using active constrained layer damping.

摘要

In this thesis, the author presents a numerical and experimental study of theudapplication of active constrained layer damping to a clamped-clamped plate. Piezoelectricudactuators with modal controllers are used to improve the performance of vibrationudsuppression from the passive constrained layer damping treatment.udSurface damping treatments are often effective at suppressing higher frequency vibrationsudin thin-walled structures such as beams, plates and shells. However, the effectiveudsuppression of lower frequency modes usually requires the additional of an active vibrationudcontrol scheme to augment the passive treatment. Advances in the technologies associatedudwith so-called smart materials are dramatically reducing the cost, weight and complexity ofudactive structural control and make it feasible to consider active schemes in an increasingudnumber of applications. Specifically, a passive constrained layer damping treatment isudenhanced with an active scheme employing a piezoceramic (PZT) patch as the actuator.udStarting with an established finite element formulation it is shown how model updating andudmodel reduction are required to produce a low-order state-space model which can be usedudas the basis for active control. The effectiveness of the formulation is then demonstrated inuda numerical study.udFinally, in the description of the experimental study it is shown how modes in theudfrequency range from 0 to 600 Hz are effectively suppressed: the two lowest modesud(bending and torsional) through active control, the higher modes (around ten in number)udby the passive constrained damping layer. The study'S original contribution lies in theudexperimental demonstration that given a sufficiently accurate model of the plate andudpassive constrained damping layer, together with a suitable active feedback controludalgorithm, spillover effects are not significant even when using a single sensor and singleudactuator. The experimental traces show, in some instances, minor effects due to spillover.udHowever, it can be concluded that the presence of the passive layer introduces sufficientuddamping into the residual modes to avoid any major problems when using only theudminimum amount of active control hardware.