B7.2 - Characterization of Dynamic Hysteresis Behavior of Ferroelectric Actuators

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
B7 - Actuators
F. Wolf, A. Sutor, S. Rupitsch, R. Lerch - Universität Erlangen-Nürnberg (Germany)
328 - 333


Ferroelectric sensors and actuators are widespread in research and industrial applications due to their ability to convert mechanical into electrical energy and vice-versa. The functional parts of such applications are often based on piezoceramic materials like lead zirconate titanate (PZT). The advantages of these materials are accompanied by a strong hysteretic large-signal behavior, directly related to the high driving levels required for actuators. In addition to that, this behavior reveals to be strongly creep-influenced and ratedependent. Both precise measurements as well as efficient hysteresis modeling are therefore essential to understand and predict this sophisticated behavior.
In our previous work, we proposed a phenomenological model for the ferroelectric polarization hysteresis which is based on the Preisach operator. Contrary to common approaches, we use an analytic weight function within the model, which reduces computing time by far. However, one of the main drawbacks of classical Preisach-type models is their inability of considering creep in the transfer characteristics of the modeled system as well as time-dependence of the input signal. Since this is in contrast to real ferroelectric behavior, we focus here on the characterization of the dynamic behavior. To our opinion, creep and rate-dependence have to be treated separately, by reason of their different impact on the shape of the polarization hysteresis loops. Therefore, we proceed with two distinct methods: A drift operator is included into our model to describe the low-pass like influence of creep. In doing so, the step response of the polarization for a given electrical field
and the typical smooth edges of minor loops are described very well by just a single additional parameter. The rate-dependent hysteresis behavior is covered using a frequency-dependent formulation of our analytic weight function with two additional parameters. Measurements of creepinfluenced and rate-dependent hysteresis loops are compared to simulations in order to verify the model output and to illustrate the need of considering both, creep and rate-dependence separately.
The measurements have been performed for discoidal piezoceramic samples from Ferroperm (diameter: 25 mm, thickness 2 mm, Pz27) using a modified Sawyer-Tower circuit.