A study on the piezoelectric actuation performance of prestressed piezoelectric unimorph actuators

The actuation performances of the prestressed piezoelectric unimorph actuators piezoelectric unimorph with mechanically prestressed substrate and thin layer unimorph driver are evaluated in terms of actuation displacement and force. During the performance tests, these prestressed piezoelectric unimorph actuators showed highly nonlinear behavior, in which their actuation performances were not proportional to the magnitude of the applied voltage, although normally they exhibit higher actuation performances at higher driving voltages. This means that the nominal piezoelectric material properties from the standard method were no longer valid for evaluating and predicting the actuation performances of the piezoelectric unimorph with mechanically prestressed substrate and thin layer unimorph driver actuators under high-voltage application. In this article, the nonlinear piezoelectric material properties, especially the elastic modulus and the piezoelectric strain coefficient, were obtained by considering the prestress, the applied voltage, and the re-poling treatment of the piezoelectric material inside the prestressed piezoelectric unimorph. Finally, actuation performance simulations were conducted using the nonlinear material properties, and the analytical results were compared and validated with the experimental results.