分割电极片状压电致动器——(一)端部位移和电场诱导应力的理论研究

Split Electrode In plane Bending Piezoelectric Actuators —(I)Theoretical Studies on Tip Displacement and Electric Field Induced Stress

研究了悬臂梁式分割电极片状压电致动器的位移特性。沿厚度方向极化的ＰＺＴ压电陶瓷薄长片，一端固定、一端自由构成悬臂梁。其上下两表面的电极均沿长度方向分割成对称的两部分。施加电场使其中一半在ｄ３１模式作用下伸长，而与其对称的另一半缩短，则压电片沿宽度方向产生弯曲，自由端便可产生致动位移。理论分析结果表明，在适当的驱动电场（不低于１００Ｖ／ｍｍ）作用下，毫米尺寸的致动器可产生微米量级的端部致动位移。电场诱导应力远小于材料的抗张强度。该分割电极压电致动器可用于精密定位，尤其适合在高密度硬磁盘驱动器的磁头定位两级伺服系统中作第二级致动器。

Displacement characteristics of cantilever split morph, a new type of piezoelectric actuator, have been investigated. In this actuator configuration, a PZT ceramic plate, with one end mechanically clamped and the other free, was poled along its thickness and divided into two symmetric parts along length by splitting electrodes. Driving voltages are preferably so arranged that one of the two parts expands by action of the “ d 31 ”while the other part, i.e., the symmetric part, contracts. This will result in a bending motion of the actuator along the direction of its width, so that the free tip deflects. Theoretical analysis indicated that micrometer order of magnitudes of tip displacement can be obtained for the actuator in millimeter dimensions at moderate driving field (bellow 100 V/mm). The electric field induced stress is much smaller than stretch strength of the piezoelectric ceramic. The split morph can be used as precision positioner, especially as the secondary actuator in dual stage head positioning servo system of high density hard disk drives.