Abstract: Analytical equations are developed to calculate the static deflection of a circular diaphragm-type piezoactuator under loads of driving voltage and uniform resisting pressure. The solution is derived using the energy minimization method and the Rayleigh-Ritz method based on the Kirchhoff thin plate theory. The proposed solution is validated via the experimental measurements under loads of voltage only, pressure only, and combined loads of voltage and pressure, respectively. The analytical and experimental results agree within 9.3%, which suggests the solution is accurate. Based on the proposed equations, the effects of the radius ratio and thickness ratio of the lead zirconate titanate (PZT) layer to the passive layer on the actuator deflections are investigated. Moreover, the effects of the pressure loads on the actuator deflections are studied as well. The results indicate that there exist the optimal radius ratio and the optimal thickness ratio to generate maximum stroke volume. It is also observed that the diaphragm deforms reversely near the periphery under the pressure load when the actuator radius ratio is lower than 0.71, which weakens the actuator performance.

Key words: diaphragm-type piezoactuator, uniform pressure load, principle of energy minimization, Rayleigh-Ritz method, micro electro mechanical systems (MEMS)