MODELING OF PIEZOELECTRIC MOTORS

This paper deals with to the theoretical analysis of two kinds of piez oelectric motors in order to determine for each of them the dedicated electromechanical coupling factors (EMC factors) which are important c hoice criteria for the energy conversion inside the piezoceramic mater ials. The fist motor is based on the non-symmetrical radial motion of a piezoelectric disk. The second type of motor uses Lamb wave propagat ion inside a piezoceramic disk. The EMC factor determination implies t he calculation of the displacements, stresses and electrical impedance of each type of motors. As a result, the rotor in contact with the mo tor stator rotates because an elliptic motion occurs on the surface si tuated between the rotor and the stator. The analytical modellings sho w that the energy conversion is characterized by one EMC factor for th e first type of motor and two EMC factors for the second type. However , in each case, two kind of waves are involved : longitudinal and shea r waves. These results are consistent with the constitutive piezoelect ric equations used for each of the considered modes.