Multifrequency piezoelectric vibration absorber for variable frequency harmonic excitations

It has been shown that piezoelectric materials can be used as passive electromechanical vibration absorbers by shunting them with electrical networks. Semi-active piezoelectric absorbers have also been proposed for suppressing harmonic excitations with varying frequency. However, these semi- active devices have limitations that restrict their applications. In a previous study, the authors have developed a high performance active-passive alternative to the semi-active absorber that uses a combination of passive electrical circuit and active control actions. The active control consists of three parts: an adaptive inductor tuning action, a negative resistance action, and a coupling enhancement action. This new device has been shown, both analytically and experimentally, to be very effective for the suppression of harmonic disturbances with time-varying frequency. In the present paper, the adaptive active-passive piezoelectric absorber configuration is modified so that it can track and suppress multiple harmonic excitations. The effectiveness of this new multi-frequency absorber design is demonstrated by comparing its performance and control power requirement to a start-of-the-art adaptive feedforward control law.