COMBINED FINITE-ELEMENT NORMAL-MODE EXPANSION METHODS IN ELECTROELASTICITY AND THEIR APPLICATION TO PIEZOACTIVE MOTORS

The proposed numerical modelling technique combines the Finite Element Method (FEM) and the normal mode expansion method. These methods have been mainly used in structural analysis. They can be extended to stea dy-state or transient problems of electromechanical structures. This t echnique associates precise description of the three-dimensional elect romechanical coupling effects by FEM to lumped parameter equivalent ci rcuits simplicity. This circuit is provided by expanding the transduce r displacement field with respect to the resonance mode basis. This op eration results in relatively few matrix decompositions in computing t he contact problems encountered in piezoactive motors analysis. It als o gives an interesting insight to the physic of electromechanical ener gy conversion. In addition, the large rigid displacement of the rotor is easily taken into account. The proposed method is first assessed th rough some classical problems to show some of its practical advantages and is subsequently applied to piezoactive motor modelling. (C) 1997 by John Wiley & Sons, Ltd.