Non-linear Piezoelectric and Ferroelectric Actuators — Analysis and Potential Advantages

Abstract

The ability to enhance and to improve the efficiency of piezoelectric actuators through extending their operational range into the non-linear regime is analytically investigated. Motivated by the limited strain actuation capabilities of the existing piezoelectric actuators, it is proposed to take advantage of the non-linear ferroelectric regime, which involves large remanent strains. In order to examine this hypothesis, an analytical model for the one-dimensional electro mechanical behavior of a ferroelectric structure operated in the non-linear range is developed. The model is applicable to rod actuators, to an active layer in a stack actuator, or to an active fiber in a Micro-Fiber-Composite actuator. The governing equations and the boundary conditions, the non-linear, hysteretic, and history-dependent constitutive relations, and the solution procedure are developed and discussed. Illustrative examples that examine an active layer operating against a dead load, against a linear spring, and against a uniformly distributed load are presented and discussed. The non-linear response is also compared with the response to electrical loads in the linear range and with the prediction of the linear piezoelectric theory. Emphasis is placed on the potential advantages that can be achieved through the operation in the non-linear range.