Extending the validity of squeezed-film damper models with elongations of surface dimensions

摘要: Compact models for micromechanical squeezed-film dampers with gap sizes comparable to the surface dimensions are presented. Two different considering both border flow and non-uniform pressure distribution effects first derived small squeeze numbers. In 'surface extension' model considered simply by calculating damping extended dimensions, in second 'border channel' an additional short fictitious channel is placed at damper borders. Utilizing a large amount of two-dimensional (2D) FEM simulation results varying mainly ratio a/h between length air height, elongations extracted using elongation models. Both linear torsional modes motion continuum regime. These show that superior, since Δa almost constant (Δa = 1.3h), leading very simple model. Next, rare gas included slip regime (Knudsen number 0 4 > 10 motion. The assumes incompressible thus maximum frequency where valid limited. typical MEMS topologies must be considered, this means below frequencies 500 kHz. To also rectangular 2D dampers, these applied directly width used compact Comparison three-dimensional (3D) simulations shows new gives excellent results, it extends validity range existing relative error smaller than 10% 16 extension useful simulating circuit level system behavior gas-damped microelectromechanical devices aspect ratios greater 2 time domains.