Large signal characterization of hard PZT materials

In the last years new high-power resonant applications of piezoceramic devices such as motors and transformers became more and more important. Therefore, there is a need for a better understanding of the nonlinear behavior of piezoceramic material under driving conditions which cause large dynamical stress.The main problem for such measurements is the self-heating of the samples caused by increasing electric driving fields and the increasing vibration velocity.This paper presents a new measurement method where the specimen are excited under constant voltage conditions in such a way that the frequency is changed step by step in the range of the serial resonance frequency. The excitation can be intermitted between two frequency steps to reduce the temperature rise of the specimen. The vibration velocity, the resonator current, the phase shift between the voltage and the current and the temperature can be recorded simultaneously.Results of transverse length vibrators made of different hard PZT materials will be presented.