Electromechanical characterization of piezoceramic elements around resonance frequencies at high excitation levels and different thermodynamic conditions

Electromechanical characterization of piezoceramic bulk elements around resonance is usually done with low-level continuous excitation signals at room temperature, but in real applications such elements are driven with different types of electrical signals, usually at higher levels and at different ambient temperatures. Both homemade and commercial soft and hard PZT piezoceramic elements were characterized using the established characterization methods that include the measurements of electrical admittance and surface displacement of the piezoceramic elements around the series resonance frequencies of two modes of vibration (radial and thickness extensional). The measurements included fast frequency sweeps at constant voltage excitation levels, burst measurements, at different temperatures and at different levels of excitation. A novel method for electromechanical characterization of piezoceramic elements that utilizes the resonance frequency tracking at different excitation levels (electric fields up to 5 kV/m, currents up to 1.3 A at resonance) and temperature conditions (up to 150 °C) has been proposed. The main idea is to keep the investigated element in resonance as the excitation level changes by constant tracking of its resonance frequency. The electromechanical parameters of the considered elements change mostly due to the nonlinear effects and the changes due to different thermodynamic conditions can be neglected when fast algorithm is applied. The decrease of the input electrical admittance magnitude is more expressed than the change of the resonance frequency when algorithm is applied.