Experimental study of the ultrasonic transducer non-linear vibrations

Conclusion

The method introduced proved to be useful in obtaining information on transducer behaviour at high power levels. With respect to ultrasonic generator design several conclusions may be drawn from the transducer characteristics. First, it was found that the current and the pick-up voltage characteristics are equivalent with respect to the information content on the transducer vibrations. Therefore, the feedback signal may be derived both from the currentI and from the voltageU _p .

It was also found that the resonance frequency of the transducerf _r varies strongly both with the power level and with the mechanical load. However, it is the resonance phase angleφ _r that is almost independent of these external changes.

Lastly, because of the jumps, the transducer may be tuned to the resonance only by lowering the frequencyf starting from an arbitrary frequency higher thanf ₁. In designing a feedback system this requirement should be taken into account.