Session: VIB-02-02 Nonlinear Systems, Phenomena and Energy Harvesting

Paper Number: 68922

Start Time: August 17, 02:10 PM

68922 - On the Mechanical Behaviour in Stiffness Compensated Piezoelectric Beams - an Experimental Investigation Towards Energy Harvesting 

In this work, a piezoelectric beam is stiffness compensated
through adding a negative stiffness introduced by attracting magnets.
The mechanism’s purpose is low-frequency energy harvesting. 
The effect of deformation speed on the beam’s stiffness is
investigated by force-displacement measurements taken at different
speeds and load resistors connected. The effect of the load
resistance on the beam’s stiffness has been found to be strongly
dependent on the deformation speed. A load that results in the
same stiffness as in a closed circuit at low deformation speed
results in a stiffer response at a faster deformation speed. 
In this research, force-displacement measurements were taken
for a piezoelectric beam that was stiffness compensated through
the addition of attracting magnets. Compensated with a 1MW
load connected, the stiffness is reduced by 92% over a 1
mm range when it is deflected quasistatically. Furthermore, it was found that memory effects in the hysteretic
behaviour, named curve alignment and wipeout, acting
between voltage and displacement in actuators, are also seen in
the relation between force and displacement. It was observed
that fitting techniques used to predict hysteretic trajectories in
piezoelectric actuators are very useful for predicting the forcedisplacement
behaviour within a closed loop. This can be very
useful when modeling the output of a stiffness compensated energy
harvester. Last, it can be concluded that the act of compensating
the stiffness of a piezo with attracting magnets can be a
suitable procedure for designing a statically balanced piezoelectric
beam, which can be used as an energy harvester.

 

Presenting Author: Thijs Blad Delft University of Technology

Authors:

E. van de Wetering Delft University of Technology
T. W. A. Blad Delft University of Technology
R. A. J. van Ostayen Delft University of Technology