MODE THEORY OF ELECTROMECHANICAL ENERGY-CONVERSION IN PIEZOELECTRIC MATERIALS

The method of eigenfunctions is generalized to the problem of dynamic electroelasticity /1/, which allows of a larger variety of physically realisable boundary conditions. Using the method of eigenfunctions a so-called mode theory of electromagnetic energy conversion is developed. Its basic idea is the establishment of a connection between the dynamic electromechanical coupling coefficient of the specified displacement field and the mode or partial electromechanical coupling coefficients of the individual modes of oscillation. The latter, being non-linear integral characteristics of normal modes, play the same fundamental role with respect to the first as the eigenfunctions (normal modes) play with respect to the overall solution of the electro-elasticity problem. The coefficients of the expansion in eigenfunctions of the displacement field which gives a maximum permissible value of the electromechanical coupling coefficient for a given geometry, position of the electrodes, and method of supplying and removing the electrical energy.