Size Dependent Dynamic Pull-in Instability Analysis of Torsional Nano Actuator

In this paper, the effect of van der Waals force and size-dependent on dynamic stability is studied for single degree of freedom model of torsional electrostatic micro/nano mirror. First, the equation of motion of system is derived and applying state space method, dynamic equations are solved and desired results are obtained. The pull-in parameters including tilting angel and voltage are considered and their dependency on van der Waals force and size effect is investigated. As well as results show that eqilibrium points of dynamic system include center points, stable focus points and unstable saddle points. The phase portraits related to these equilibrium points created periodic orbits, heteroclinic orbits, and homoclinic orbits. Furthermore, in present study, using modified couple stress thoery the influence of size effect on amplitude and frequency of system is considered. Obtained results show that the model presented in this paper is very good agreement with experimental results