Non-linear and hysteretic processing of piezoelement: Application to vibration control,wave control and energy harvesting

Abstract

The proposed processing is applied on the voltage output, image of the vibrating displacement u(t), of a piezoelement (patch) bonded on a vibrating structure. It is based on a non-linear processing which, in the simplest version, short circuit the voltage output for a very brief time duration when the voltage reaches a maximum or a minimum. Right after the switching, the voltage is relaxed and becomes again an image of u(t) at the patch location. Repeating the switching for each max and min of the voltage signal results in a transformed voltage waveform that is magnified and time shifted with respect to the non switched waveform. As a matter of fact, it can be shown that the processed voltage can be spilt in two waveforms: one, V _{1} (t), being the exact image of the displacement u(t) while the second, V _{2} (t), is related to the sign function of the vibration speed. Consequently V _{2} (t) appears to act as a mechanical dry friction force which leads to efficient and frequency independent removal of the energy stored in the piezoelement. Taking advantage of this particular energy removal, several topics (vibration damping, wave control, energy harvesting) have been experimentaly addressed.

For the vibration damping, the experimental results obtained with the proposed semi-active approach are close to the active performances. Acoustic wave reflection reductions of 17∼dB and 34∼dB have been respectively obtained for air and water media and the scavenged energy using the switch process at fixed displacement is almost ten times higher than the harvested energy using a standard processing.