Static instability of beam-type NEMS subjected to symmetric electrostatic actuation based on couple stress theory and Timoshenko beam theory

The behavior of nanoelectromechanical systems subjected to symmetrical electrostatic actuation and symmetrical Casimir intermolecular force has been investigated. Two different phenomena (i.e. electromechanical bifurcation and electromechanical buckling) have been considered to explore the static electromechanical instability of such systems. The Timoshenko beam model has been employed to find the effect of shear deformation on these systems. Modified couple stress theory has been used to investigate size-dependency. Besides, the compressive and tensile residual stresses of nanobridges have been measured on the basis of electromechanical buckling. The governing equations and corresponding boundary conditions have been obtained by means of the principle of minimum potential energy. Finally, following validation of results, the effects of material length scale, length, shear deformation, beam geometry, and gap distance on the symmetric electromechanical behavior have been discussed and examined.