Comparison of Power Density Characteristics among Disk and Plate Shaped Piezoelectric Devices

High power density piezoelectric devices are required for smaller actuators and transformers. These devices are expected to perform similar to, or better than their larger scaled counterparts. Despite the superiority over their electromagnetic conjugates, piezoelectric devices are still limited in the amount of power they can handle. Commercial materials can carry vibration velocities up to 0.5 m/s (measured for a rectangular plate), which translates roughly into 25W/cm(3) power density. In this work, we examined the effect of shape and aspect ratio to the power density of two common actuator shapes, k(31) type rectangular plates and k(p) type disks. Results demonstrate that the power density of disks can be an order of magnitude higher than plates. While the power density is 10 times higher, the equivalent resistance of a disk shaped resonator is 10 times lower, making it a better candidate to match low output impedances, needed for high power transformers. Disks also show higher mechanical quality factors when considering a fixed output power per volume as a criterion. The results of this study validate the use of disk shaped actuators for high power density applications including as transducers and step down transformers. (C) 2010 The Japan Society of Applied Physics