Secondary Stresses in a Stress-Pulse-Activated Piezoelectric Element

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Abstract
Previous treatments of stress-pulse-activated piezoelectric and ferroelectric stress gauges and power generators neglect the secondary stresses produced by circuit-enforced fields in not-directly-stressed parts of the transducer. It is pointed out that under short-circuit conditions these secondary stresses generate strong effects in materials with high electromechanical coupling factors. To demonstrate this, a thin plate activated by a plane rectangular low-amplitude stress front is considered. A rigorous theoretical analysis is sketched for this configuration. It is found that short-circuit current pulses generated by the stress-front transit are not rectangular, but vary exponentially in time. The exponent is proportional to the square of the electromechanical coupling factor and depends on the mechanical boundary conditions. Supporting experiments are reported.