Active constrained layer damping of plate vibrations: a numerical and experimental study of modal controllers

In this paper the authors address the problem of suppressing the vibrations of a clamped-clamped plate using an active constrained layer damping treatment. This treatment involves adding viscoelastic and metallic constraining layers to the host plate and then augmenting this arrangement with an active feedback scheme using piezoelectric actuators. The basis of the control strategy is an effective model of the plate together with the passive damping treatment. The paper summarizes the modelling procedures including the finite-element formulation, model reduction and model updating. By this means a low-order model, capable of accounting for the observed behaviour, is developed.

Emphasis is placed upon the design and implementation of active modal controllers based upon the reduced and updated model. Four actuator/sensor configurations are examined in both numerical and experimental studies. It is shown that effective control of the first two modes of vibration (bending and torsion) can be achieved using only a single actuator and single sensor. However, the most effective configuration involves two actuators and two sensors operating as two independent control channels. It is shown that through suitable design, the active constrained layer damping treatment is capable of avoiding problems due to spillover effects.