To keep pace with recent advances in micro robotic structures demands actuator technologies which can deliver high power and precise motion. For electroactive material based actuators, high power typically implies either high field or high current drives which may lead to greater nonlinearities such as saturation, softening, and increased loss. Physical modeling of actuators is normally taken to be linear since the range of displacements, applied loads, and applied fields is typically small. If extrapolated to high drive conditions, these linear models significantly over predict the power which can be delivered. For actuators driving dynamic systems, a complete nonlinear model of the system will improve controllability and give more accurate estimations of power delivery capabilities. Here static nonlinearities and dynamic linear and nonlinear parameters are derived for high performance piezoelectric bending actuators.