SUMMARY

The primary focus of this research is the development of an improved micromechanical constitutive model based on the experimental observations of single crystal and ceramic specimens under large field loading. This model will account for the evolution of variant and phase volume fractions and will incorporate the orientation dependence of off-axis crystal cuts. Utilization of a current micromechanically based finite element model to simulate partially electroded stack actuators will be accomplished to gain insight into ferroelectric switching behavior in regions with high field gradients. This research will also address the ramifications of the micromechanical model for development of a phenomenological model with internal state variables for phase changes. Furthermore, research has been accomplished on the modeling of unimorph bending actuators that illustrates the need for inclusion of the nonlinear hysteretic behavior of ferroelectrics. To this end, this research will also consider the implications of inclusion of the micromechanical model into bending-type actuator design.