Investigation of Controllable Modes in Active Vibration Cancellation Induced by Piezoelectric Patches

Abstract

Piezoelectric (PZT) patches are widely preferred for actuators and sensors for achieving active vibration cancellation (AVC). When PZT actuators and sensors are placed at the region of maximum strain energy for structural modes, there are still uncontrollable and controllable modes in the actual application. When an uncontrollable mode is excited, the structural vibration problem may not be solved by AVC, and may even be aggravated. However, a few studies have specifically targeted this problem. In this study, the controllable modes of a plate with free boundaries are investigated to ensure the AVC effect. To specify the controllable modes in advance, a criterion for controllable modes is proposed. The proposed criterion is firstly obtained by defining the ratio of the open-loop and closed-loop energies of AVC, and then simplified by considering the dominating modes. Corresponding simulations and experiments are conducted on a smart plate consisting of PZT patches to verify the correctness of the theoretical analysis. Results show that the proposed criterion is reliable to specify the controllable modes. The vibration response of the plate is significantly attenuated at the selected controllable mode, and conversely enlarged at a specified uncontrollable mode. It is verified that controllable modes can be effectively predicted by the proposed criterion, which promotes the application of AVC.