Affiliations: [a] Laboratoire de Génie Electrique et
Ferroélectricité INSA de Lyon, France
Correspondence:
[*]
Corresponding author: LGEF - INSA de Lyon, Bâtiment G.
Ferrié, 8, rue de la Physique, 69621 Villeurbanne Cedex, France. Tel.:
+33 472 43 81 58; Fax: +33 472 43 88 74; E-mail: daniel.guyomar@insa-lyon.fr
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.
