NONLINEAR BEHAVIOR OF AN ULTRASONIC TRANSDUCER

A transducer model, based on nonlinear piezoelectric constitutive equa tions, has been developed to describe the harmonic generation that occ urs on current or velocity signal analysis when the transducer is driv en at high voltage. The symmetrical Langevin transducer studied close to its resonance frequency is composed of Navy III type power ceramics . The nonlinearities create an energy spread over the frequency spectr um and consequently result in an amplitude saturation effect at the dr iving frequency, which can be interpreted in terms of the loss mechani sm. Experiments have been carried out to measure the nonlinear losses and the harmonic amplitude evolutions. Results are given and discussed . Eventually, by experimental means, identification of the influential nonlinear coefficients permits comparison between theoretical predict ions and experimental results.