An Analysis of Squeeze-Film Damping in a Piezoelectric Bender ElectroFluid Converter

A unique proportional electrofluid converter design is presented. The valve employs two piezoelectric benders acting as flappers on two nozzles. The benders are highly resonant, resulting in extreme sensitivity to external vibration and poor fidelity for transient inputs or signals near resonance. Mounting the two benders against a flat plate greatly increases the damping of the benders. This increase in damping results from the pumping of fluid into and out of the film between each bender and the flat plate. The effect is similar to that encountered in air bearings and known as squeeze-film damping. A mathematical model for the bender including the squeeze-film damping is developed which allows the beam-wall interaction to be optimized for a given first mode response. The mathematical model is also normalized and it is shown that the squeeze-film damping can be described using a dimensionless design parameter.