DAMPING CHARACTERISTICS OF BEAM-SHAPED MICRO-OSCILLATORS

The damping characteristics of beam-shaped microactuators that oscilla te in the transverse direction are analytically evaluated to establish a design method that minimizes energy consumption and increases dynam ic performance. The damping force due to airflow is calculated using t he Navier-Stokes equation, the accuracy of which is verified by compar ing the calculated damping with experimental results. The contribution s to the damping due to squeeze force, internal friction, and support loss are calculated by using the Reynolds equation, structural damping theory, and a two-dimensional theory of elasticity, respectively. The final formulae, obtained in simple and closed forms for easy use in t he actual design process, are then used to evaluate the relationships between the beam size and the damping ratio of silicon cantilevers, Pe rmalloy cantilevers, and Permalloy spiral springs. Finally, the step r esponse of a Permalloy cantilever is calculated and the relationship b etween beam size and settling time is determined.