In this paper, we demonstrate how efficient low-order dynamical models for micromechanical devices can be constructed using data from a few runs of fully meshed but slow numerical models such as those created by the finite-element method (FEM). These reduced-order macromodels are generated by extracting global basis functions from the fully meshed model runs in order to parameterize solutions with far fewer degrees of freedom. The macromodels may be used for subsequent simulations of the time-dependent behavior of nonlinear devices in order to rapidly explore the design space of the device. As an example, the method is used to capture the behavior of a pressure sensor based on the pull-in time of an electrostatically actuated microbeam, including the effects of squeeze-film damping due to ambient air under the beam. Results show that the reduced-order model decreases simulation time by at least a factor of 37 with less than 2% error. More complicated simulation problems show significantly higher speedup factors. The simulations also show good agreement with experimental data.

Generating efficient dynamical models for microelectromechanical systems from a few finite-element simulation runs

In this paper, are describe how a few simulations of fully meshed dynamical problems can be used to construct efficient low-order models for system-level design of microstructures. We report on the use of this method to capture the measured behaviour of a pressure sensor based on the pull-in time of a beam. Results show that the reduced order model decreases simulation time by at least a factor of 37 while achieving good agreement with experimental data.

Low-order models for fast dynamical simulation of MEMS microstructures

https://www.research.manchester.ac.uk/portal/files/36945455/FULL_TEXT.PDF

The efficient computation of the nonlinear dynamic response of a foil–air bearing rotor system

A journal bearing simulation tool developed to aid the design of the MIT microturbo-machine bearings is described This tool uses an orbit method with a pseudospectral technique for treating the Reynolds equation Comparison is made to various published data Two types of stability chart are presented and their application to turbo-machine bearing design is discussed Simulations of imbalance, noncircular geometry, and nonuniform pressures at the bearing ends are also demonstrated

Pseudospectral Orbit Simulation of Nonideal Gas-Lubricated Journal Bearings for Microfabricated Turbomachines

Hydrodynamic performance of gas microbearings, fabricated with deep X-ray lithography and electroplating, will be presented in this article. Static performance in terms of load parameters and attitude angles was calculated using Molecular Gas Lubrication (MGL) theory. Threshold speed and allowable rotor mass were calculated to investigate safe operating conditions of the fabricated gas microbearings using orbit simulation. Finally, improved bearing designs were proposed to increase stability.

Hydrodynamic Performance of Gas Microbearings

: One of the most important considerations in designing a high-speed, gas-lubricated, self acting journal bearing is the instability of the journal under a given operating condition. Intensive research in this direction has led to a number of significant contributions in the past five years. The present paper extends the method of Cheng and Trumpler to study the stability of plain cylindrical gas journal bearings of finite length. Both equilibrium and stability results were obtained.

C. H. T. Pan

Papers

Stability Analysis of Gas-Lubricated, Self-Acting, Plain, Cylindrical, Journal Bearings of Finite Length, Using Galerkin’s Method