A nonlinear semipassive vibration damping using piezoelectric elements

The proposed approach is based on a nonlinear filtering of the piezoelements output voltage and does not require any tuning to ensure damping performances over a large bandwidth. The output voltage is short circuited for a very brief period of time when the voltage reaches a maximum or a minimum. As a consequence of this filtering, the voltage gets distorted, amplified, and shifted in the time domain. It can be split in two signals, one is in phase with the vibration displacement and contributes to the potential energy while the second is in phase with the vibration speed and participates to the energy damping. The technique is semipassive since it requires a very low electrical power to drive the switch sequences. Experimental data show that the switching technique leads to better damping performances than purely passive methods whatever the natural damping of the structural material is. Furthermore, switching the piezovoltage through a small inductor leads to a voltage amplification and consequently to an increase of the damping. Damping capabilities range from 6 dB for an epoxy beam to nearly 20 dB for a steel beam even in the low frequency regime. Experimental results and theoretical interpretations will be presented.