Dynamic Nonlinearities in Piezoelectric Sonar Ceramics.

摘要

A measurement system was established to probe the nonlinear response of piezoelectric ceramic rings driven at their fundamental 'hoop-mode' resonance frequencies with progressively increasing electrical driving fields, up to and including the field at which fracture occurred. Initial measurements indicated that Navy Type-I ceramic materials from different suppliers differed substantially in output strain level (a 14 percent difference in strain amplitude for dimensionally similar rings at 8kV/m) and fracture strength as well as in the onset and degree of nonlinear response. The measurements also included input current, resonance frequency, and mechanical quality factor versus electric driving field. A nonlinear theory for interpretation of the measured data was developed for the piezoelectric ring, and the resulting differential equation of motion was programmed in an analog computer. The output plots showed nonlinear 'jump' phenomena in the frequency region about resonance as well as 'beat' phenomena in the current envelope response, both of which were observed experimentally. Therefore, analog computer techniques may be the most convenient means of interpreting and understanding the nonlinear behavior of ceramic transducer materials. (Author)