Determination of the stiffness properties of a complex RF MEMS by superposition and finite elements method

In this study, the deflection and stiffness of a micro cantilever beam with a rectangular notch are derived analytically by considering a non-uniformly distributed load as a cause of deflection, since the shape of a distributed load at the exact collapse time is not uniform in the real scenario. In order to calculate the deflection, due to the design of the beam structure, the superposition method is employed as well as the fundamental principles of mechanics. Moreover, it is also utilized in the subsequent stiffness calculations. Particularly, the stiffness concept is discussed under three different subsets: natural, actuation, and release stiffness, as they are essentials for the switching operations. In addition to the analytical study, FEM simulations are also carried out using CoventorWare in order to compare with the derived models. As the results reveal that accuracies of both the analytical models and simulations are acceptable, this study provides a utilitarian framework for designing different complex MEMS.