Degradation Mechanisms of Ferroelectric Ceramic Actuators
Progress rept, 1 Oct 1992-30 Sep 1993
CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL ENGINEERING
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Ferroelectric oxides deform appreciably under electric field. They are used now as large strain ceramic actuators where a moderate electric voltage can deliver an appreciable mechanical motion. The electrostrictive and piezoelectric strains are incompatible around inhomogeneities, such as electro edge and inclusions. Cracking under electric loading has been identified in recent years. This program seeks to quantify various cracking mechanisms so that future actuator design will have scientific basis. Crack growth under cyclic polarization switching is studied experimentally using a lead lanthanum zirconate-titanate ceramic. We find that the crack growth rate is sensitive to temperature, loading magnitude and frequency. Several mechanisms have been proposed to account for the cyclic crack growth. One such model has been analyzed in detail. More detailed experiments on such cracks are in progress.
- Electrical and Electronic Equipment
- Ceramics, Refractories and Glass
- Electricity and Magnetism