Active tuning and coupling enhancement of piezoelectric vibration absorbers for variable-frequency harmonic excitations in multiple degrees of freedom mechanical systems

摘要

It has been shown that piezoelectric materials can be used as electromechanical vibration absorbers when they are shunted by an electrical network. Semi-active piezoelectric absorbers have also been propsoed for the purpose of suppressing harmonic excitations with varying frequencies. These smei-active devices can be constructed using a variable inductance or variable capacitance element in the shunt circuit, however both of these implementations have several limitations that restrict their practical use. The design presented here is a high performance alternative to semi-active absorbers that uses a combination of a passive RL circuit and an adaptive feedback law to suppress harmonic excitations with varying frequency. The adaptive tuning is accomplished by simulating a viariable inductor using feedback. An equation for the optimal tuning of the piezoelectric absorber on a general MDOF structure is derived. Next, it is illustrated that the performance and robustness of the piezoelectric absorber can be increased by using additional active actions to reduce the circuit resistance and enhance the coupling of the piezoelectric. Two lmethods for increasing the effective couplint of the absorber are examined-a negative capacitance shunt and active coupling feedback. Finally, the effectiveness of the proposed algorithm is demonstrated experimentally.