NUMERICAL STUDY ON PULL-IN INSTABILITY ANALYSIS OF GEOMETRICALLY NONLINEAR EULER-BERNOULLI MICRO BEAM BASED ON MODIFIED COUPLE STRESS THEORY

摘要

In this paper, the static pull-in instability of beam-type micro-electromechanical systems (MEMS) is theoretically investigated. Two engineering cases including cantilever and double cantilever micro-beam are considered. Considering the mid-plane stretching as the source of the nonlinearity in the beam behavior, a nonlinear sizedependent Euler-Bernoulli beam model is used based on a modified couple stress theory, capable of capturing the size effect. By selecting a range of geometric parameters such as beam lengths, width, thickness, gaps and size effect, we identify the static pull-in instability voltage. A MAPLE package is employed to solve the nonlinear differential governing equations to obtain the static pull-in instability voltage of microbeams. The results reveal significant influences of size effect and geometric parameters on the static pull-in instability voltage of MEMS.