Modelling the electromechanical coupling of RF switch using Extended Finite Element

Many Micro-Electro-Mechanical Systems deals with mechanical structures moving in electrostatic field such as RF-switches, micro-resonators and micro-rotors. For this type of problems it is required to evaluate accurately the electrostatic forces acting on the devices. In this study we focus on conducting mechanical structures suspended above a substrate. A voltage difference is applied between the two parts and electrostatic forces that appear on the structures tend to make it stick to the substrate. This type of problem is strongly nonlinear since the electric domain is strongly modified during structural deformation. In order to simplify and to improve the electric field calculation, the eXtented Finite Element method is applied to cope with the moving boundary problem coming from the structural displacement. Preliminary studies in one-dimension have shown that one can obtain good results in the computation of electrostatic potential using X-FEM method and that the evaluation of the electrostatic forces remains accurate until arriving in contact. In this paper the extension in two dimensions will be presented and a comparison between the forces computed using the classical Finite Element Method and the Extended Finite Element Method will be provided.