Evaluation of Thermal Strain Suppression Design of Piezoelectric Ceramic Actuators

Abstract

Piezoelectric ceramic actuators with less thermal strain were designed by symmetrically stacking two kinds of piezoelectric ceramics plates whose linear expansion coefficients were positive and negative, and their performance was evaluated. Three types of actuators were examined, which have a different stacking direction. The electromechanical material constants were evaluated by a one-dimensional model and the results were compared with a three-dimensional finite element analysis. The result showed that the piezoelectric constant of an actuator stacked in the perpendicular direction to the electric field was about three times larger than that of an actuator stacked in the parallel direction, even though the volume ratio between the two kinds of plates was almost the same between the stacking types. This is because most of the voltage in the latter type was distributed to the piezoelectric plate with low permittivity and low piezoelectric constant. Therefore, it is important to consider the stacking direction and the permittivity in the design of the actuators. The three-dimensional finite element analysis showed the linear expansion coefficient was not zero even though it was zero in the one-dimensional model. Therefore, three-dimensional analysis is necessary for precise design, although the one-dimensional model provides good estimation of the electromechanical property.