PERFORMANCE EVALUATION OF THE PRE-STRESSED PIEZOELECTRIC UNIMORPH USING NONLINEAR PIEZOELECTRIC PROPERTIES

Piezoelectric actuators operate when the electric field (voltage) is applied to them. This piezoelectric behavior is defined using piezoelectric strain coefficients which are generally assumed to be constant. However, when high electric fields are applied to the piezoelectric actuators the piezoelectric strain constant may increase up to more than twice of the nominal value and, thus, cannot be considered as a constant value. Besides, in case of the pre-stressed piezoelectric unimorph actuators, the stress conditions inside piezoelectric actuators can affect piezoelectric behaviors. For reasons mentioned above, actuation performance of PUMPS actuator, which is one of the pre-stressed piezoelectric actuators developed by present authors, cannot be predicted accurately without consideration of piezoelectric nonlinearities such as voltage and stress effects. Generally, the piezoelectric behavior is mainly affected by the piezoelectric strain coefficient and the elastic modulus. Therefore, the voltage and stress effects on the piezoelectric strain coefficient and the elastic modulus of piezoelectric layer were investigated, and the results were used for prediction of actuation performance of PUMPS. Taking the nonlinear material properties of the piezoelectric layer into account, the actuation performance of PUMPS was accurately predicted in this study.