Domain reorientation of piezoelectric bending actuators

Several types of bending actuators were studied in the present paper to investigate the effect of actuator configuration on domain reorientation. The configurations studied include series bimorph, parallel bimorph, monomorph, unimorph and piezo tube actuator. It was found that due to electric field redistribution, one-loop polarization-shaped displacement hysteresis curve was formed in the antiparallel-poled series bimorph and piezo tube; while in monomorph actuator, the two-looped displacement curve was observed. In the case where the electric field without redistribution is exactly applied on the individual ceramic plate, such as in the case of parallel bimorph and unimorph, the shape of the displacement curve depends on the structure of the actuator. The parallel bimorph gives a three-looped displacement hysteresis curve; while the unimorph gives a butterfly-shaped curve. The superposition theory was proposed to explain the formation of the different displacement hysteresis curves.