Abstract:

In recent years interest in the use of electrostrictive materials in transducers has increased greatly, in view of the development of materials such as lead magnesium niobate (PMN) and lead magnesium niobate/lead titanate (PMN/PT). These materials produce approximately an order of magnitude greater strain than that produced by piezoelectric materials when subjected to a comparable electric field level. Unfortunately, the behavior of these materials cannot be linearized by the usual procedure, since they will not retain a significant remanent pole for more than a short time. Hence, it is necessary to develop methods for predicting transducer performance based directly on the electrostrictive properties of these materials. This paper presents an equivalent circuit useful for predicting the first-order behavior of a transducer incorporating an electrostrictive mamterial in the form of a plate-shaped actuator. The methods used are sufficiently general that the resulting circuit is also applicable to piezoelectric and electrostatic transducers. Thus, in this sense, the equivalent circuit presented is ``universal,'' since it is equally applicable to electrostrictive, piezoelectric, and electrostatic transducers which utilize a plate-shaped actuator.