Nonlinear characterization of high power transducers

A method for characterizing the nonlinear electromechanical coefficients and losses using measurements at low frequency and at resonance frequency is proposed. Then an electrical equivalent circuit synthesizing the whole nonlinearities is built up : it includes two components (a reactance and a resistance), which are dependent on the amplitude of the electric displacement, connected at the input of the low level Mason equivalent circuit. Applying such a circuit on piezoceramics or transducers driven at high power confirms that better performances are achieved near the antiresonance frequency. Physical interpretation is based on conflicting influences of electric field and vibration velocity on the motion of the non 180 domain walls.