Piezoelectric pseudo-shear mode actuator made by L-shape joint bonding

A new type of pseudo-shear mode piezoelectric actuator is described which uses a particular bonding design on a multilayer piezoelectric ceramic stack. In this actuator, long thin rectangular surface electroded PZT piezoelectric sheets are stacked and epoxy bonded at alternate ends. The poling directions in the sheets are selected such that a common potential difference applied to the plates produces alternate lengthening and contraction through the action of d₃₁ and thus a cumulative displacement over the whole length of the effectively "folded" ceramic. The rectangular stack of plates thus " shears" over to produce a substantial shear angle, hence the title of pseudo-shear mode actuator. In this paper, a new higher strength bonding for the anchoring of the alternate ends is discussed, and shown to permit the generation of large unloaded surface displacements and a high blocking force.