High Coupling Factor Piezoelectric Materials for Bending Actuators: Analytical and Finite Elements Modeling Results

New giant piezoelectric factor materials such as PMN-PT and PZN-PT were researched during the last decade and are actually becoming commercially available. As they seem very attractive for actuator designs, we studied their potential in replacing PZT ceramics. In a first comparative approach, we tested a series of classic rectangular composite bimorph structures of different combinations of thicknesses. The goal consisted in evaluating the quantitative improvement in terms of maximum displacement range and blocking force value. The resulted ratio is situated between 3 to 5. Given the very high coupling factor of PMN-PT and PZN-PT that may reach 0.97 (the PZT ranges around 0.3), we noticed large differences between the existing analytical results and the finite elements simulations performed under COMSOL Multiphysics, which finally, for this type of materials, proved to be much more reliable.