Electrostatic frequency tuning of flat and curved microplates

The effect of distributed electrostatic force on the resonant behavior of initially flat and curved circular aluminum microplates fabricated by a mold-less stamping technique is experimentally investigated. Fabrication-related residual stress is estimated through a correlation between the experimental results and finite element analysis predictions. It is shown that the flat plates vibrating around their undeformed state exhibit hardening nonlinearity, whereas the curved plates exhibit softening nonlinearity. Curved plates vibrating around the deformed equilibrium states, induced by a steady DC voltage, manifest a much higher-frequency tunability as compared to the flat plates. In the bistable curved plates, a frequency sensitivity to the electrostatic loading is increasingly more pronounced in the vicinity of the snap-through limit point. The experimental results are consistent with the finite element model predictions.