Abstract：The size-dependent pull-in voltage of electrostatically actuated MEMS is studied using strain gradient elasticity theory. The microbeam model and microplate model are derived respectively via the principle of minimum potential energy. The generalized differential quadrature method and pseudo arclength algorithm are used to solve the high-order PDEs. It is shown that the normalized pull-in voltage predicted by the new models increases nonlinearly with the decrease of the structure thickness, exhibiting size effect (and the size effect is particularly strong when the structural thickness is on the same order of the characteristic material length scale parameter); while the corresponding classical models do not exhibit such a size effect. The two new models may be regarded as extensions of the corresponding classical ones. This study may be helpful to characterize the mechanical properties of small sized MEMS, or guide the design of microstructures for a wide range of potential applications.
2011, Vol. 32 
