Analysis
of electrostatic actuated microbeams
(but no experimental results)
Recent work
at Universit`a di Udine, Italy has explored the effectiveness of
current mathematical methods in predicting the mechanical behaviour of
electrostatically actuated microbeams for large deflections. However
they have no experimental validation to verify thier model!
In this work a
cantilever microbeam with length l = 100 µm and thickness t = 0.4
µm has been considered. The material of the beam is
polycrystalline silicon, with Young modulus E = 166 GPa and Poisson’s
ratio ν = 0.36. The beam is in a vacuum. The large deflection referred
to in the work is not immediately obvious, though appears to be 80µm (a vertical
deflection greater than 80% of the beam length) for 1700 volts
actuation voltage.
They develop their own alternative approach based on a sequential field
coupling
(SFC) algorithm, claimed to be more suitable to deal with strongly
non-conservative electrostatic loads.
They claim that
the solution of an electromechanical coupled problem introduces
"remarkable computational complexities, which are increased when
geometrical non-linearities due to large microstructure deflections
also have to be considered". Their new method based on an SFC approach
in which electrostatic loads are gradually applied at each iteration to
the deformed shape of the structure. This may be more effective to
describe the microbeam behaviour; particulary when the voltage at which
instability occurs is also evaluated and post-instability solutions
predicted.
March 2004 publication
Reference:-
If you have any
questions
or want further information,
please contact
Professor R.B.Yates at R.Yates@mems.org.uk
©2004 R.B.Yates All rights reserved.