Power ultrasound is an emerging technology which exploits piezo-electrically generated waves of high intensity to produce and/or assist different industrial and medical applications. Power ultrasonic transducers are dynamic systems made up of one or several tuned components, which typically shows an inherent nonlinear behaviour. Such a behaviour, may be the cause of disturbances, instabilities and system inefficiencies that jeopardize the scalability of tuned transducers at industrial level. The nonlinearities detected in the vibration behaviour of the ultrasonic devices have their origin in the nonlinear characteristics of the piezoelectric ceramics used to convert the electrical driving energy applied to the tuned assemblies in mechanical oscillations. As far as we know, apart from late work by the authors, no previous research has been found in the literature in alternative designs to enhance the dynamics of power ultrasonic transducers.
The authors have developed an experimental method to separate thermal contributions from the nonlinear dynamic responses of piezoelectric ultrasonic transducers, usually exhibited around tuned resonant frequencies. This method is based on the use of a burst type excitation signal to drive the transducers. The method was employed to investigate the effect of the positioning of the piezoelectric ceramics on the softening response characteristic of power transducers.
This work deals with the enhancement of the vibration behaviour of high Q multi-component resonant ultrasonic transducers used for airborne applications. Optimal configurations of Langevin piezoelectric transducers will be studied to provide design solutions capable of diminishing the nonlinear behavior of tuned systems, and as a result, allowing their scale-up for industrial purposes.
