Validation of compact models of microcantilever actuators for RF-MEMS application

Microcantilever specimens for in-plane and out-ofplane bending tests are here analyzed. Experimental validation of 2D and 3D numerical models is performed. Main features of in-plane and out-of-plane layouts are then discussed. Effectiveness of plane models to predict pull-in in presence of geometric nonlinearity due to a large tip displacement and initial curvature of microbeam is investigated. The paper is aimed to discuss the capability of 2D models to be used as compact tools to substitute some model order reduction techniques, which appear unsuitable in presence of both electromechanical and geometric nonlinearities.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

RF-MEMS beam components : FEM modelling and experimental identification of pull-in in presence of residual stress

In this paper an experimental validation of numerical approaches aimed to predict the coupled behaviour of microbeams for out-of-plane bending tests is performed. This work completes a previous investigation concerning in plane microbeams bending. Often out-of-plane microcantilevers and clamped-clamped microbeams suffer the presence of residual strain and stress, which affect the value of pull-in voltage. In case of microcantilever an accurate modelling includes the effect of the initial curvature due to microfabrication. In double clamped microbeams a preloading applied by tensile stress is considered. Geometrical onlinearity caused by mechanical coupling between axial and flexural behaviour is detected and modelled. Experimental results demonstrate a good agreement between FEM approaches proposed and tests. A fairly fast and accurate prediction of pull-in condition is performed, thus numerical models can be used to identify residual stress in microbridges by reverse analysis from the measured value of pull-in voltage.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

A Compact Three-Dimensional Two-Layer Flexible Hinge

The paper proposes a new three-dimensional flexible hinge formed of several serially linked straight- and circular-axis segments that are disposed of in two layers. The novel hinge configuration is capable of large displacements and can be implemented in precision-compliant mechanisms that need to cover large spatial workspaces. Based on simplified geometry, an analytical compliance model is formulated that connects the loads to the displacements at one end of the hinge. Finite element simulation and experimental prototype testing of actual-geometry hinge configurations confirm the analytical model predictions. A related compliance-based analytical model evaluates the maximum loads that can be applied to the hinge and the resulting displacements. The two small-deformation analytical models are subsequently utilized to investigate the relationship between geometric parameters and the hinge performance qualifiers

Validation of compact models of microcantilever actuators for RF-MEMS application

Electromechanical behavior of microcantilever specimens for in-plane and out-of-plane bending tests, currently designed by industry for Radio-Frequency application, are here analyzed. Main features of these two layouts are discussed. In particular, a comprehensive experimental validation of 2D and 3D numerical models implemented to predict the coupled electromechanical behavior of these microsystems is performed. Effectiveness of plane models to predict pull-in, in presence of geometric non-linearity, due to large tip displacement and initial curvature of microbeam, is investigated. Three dimensional models are then used to investigate the local effects of the electric field and the limits of the two dimensional approach. In addition, this paper investigates the effectiveness of 2D models to be used as compact numerical tools in substitution of some known Model Order Reduction techniques, which unfortunately are unsuitable to predict simultaneously the effects of both the electromechanical and geometric non-linearitie

FEM modelling and experimental characterization of microbeams in presence of residual stress

Out-of-plane bending tests are here used to experimentally validate some numerical models of microbeams actuated by the electric field. Out-of-plane bending microcantilevers and clamped\u2013clamped microbeams often suffer the presence of residual strain and stress, respectively, which affect their static and dynamic behaviour and pull-in voltage. In case of microcantilever an accurate modelling has to include the effect of an initial curvature due to microfabrication process, while in double clamped microbeams constraints may impose a pre-loading caused by a tensile stress. So-called geometrical nonlinearity sometimes occurs, when microcantilever exhibits large displacement, or because of the mechanical coupling between axial and flexural behaviours in double clamped microbeams. Modelling this kind of nonlinearity is an additional goal of this study. Experiments demonstrated a good agreement with results of FEM approaches proposed. In the case of microbridges numerical models are used to identify the residual stress. A reverse analysis is implemented, the axial pre-stress is calculated by means of the measured pull-in voltage