HIGH-DISPLACEMENT PIEZOELECTRIC ACTUATOR UTILIZING A MEANDER-LINE GEOMETRY .2. THEORY

A simple electromechanical model of the meander-line actuator, whose characteristics are presented in a separate companion paper, is developed. The model consists of a voltage-actuated force source, which is the result of the piezoelectric properties of the bars that make up the actuator, in parallel mechanically with a stiff spring that models the compression-expansion response of the piezoelectric bars. This parallel combination is in series mechanically with a second spring. This series connection is subjected to large bending moments that cause the stiffness of this second spring to be much less than the stiffness of the spring in parallel with the force source. The addition of stiffeners to the actuator can significantly reduce these bending moments and thus increase the stiffness of this second spring. As a result, the force generation capability of the actuator is significantly increased without affecting its displacement capability.