CALCULATION OF QUASI-STATIC ELECTROMECHANICAL COUPLING-COEFFICIENTS FOR ELECTROSTRICTIVE CERAMIC MATERIALS

The quasi-static coupling coefficients, k13 and k33, for electrostrict ive ceramics are computed analytically. The calculation is based on a three-dimensional constitutive relation that models both electrostrict ion and nonlinear dielectric behaviors. The results show that the coup ling factors depend on the amplitudes of the applied ac field and the dc bias, as well as the mechanical prestress. For an actuator without bias voltage or prestress, the coupling coefficients approach an asymp totic value with increasing electric field. The primary coefficients, k13 and k33, for a lead magnesium niobate, Pb(Mg1/3 Nb2/3)O3-PbTiO3-Ba TiO3 (PMN-PT-BT), based relaxor ferroelectric are computed as an examp le. The results show that the coupling coefficients for PMN-PT-BT mate rials are roughly comparable with those of existing piezoelectrics. Th ese coefficients are important parameters for material section and pow er source design for transducer devices.