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August 19, 2010 8:58pm UTC

MEMS Piezoelectric (Voltage vs. Eigenfreq)

Hi,

I am changing the voltage across the piezoelectric beam actuator I've created. I expect to see a different set of eigenfrequency numbers when I change the voltage. However, the numbers remain the same.

Under solve parameters
Analysis Types: Piezo Solid (smpz3d) Eigenfrequency with Eigenfrequency Solver.

I'm reading the eigenfrequency numbers from
Point evaluation > Solution to use > eigenfrequency

Any ideas??

-Albert

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January 7, 2011 6:35am UTC in response to Chris Menzel

Re: MEMS Piezoelectric (Voltage vs. Eigenfreq)

Hi

Indeed what Physical phenomena should change the Eigenfrequency of a beam if you apply a voltage ?

f[Hz]= 1/2*pi*sqrt(K[N/m]/m[kg])

Probably you expected a stress stiffening via "K" or somewhat like that ?

then you must use Matlab and v3.5a or just COMSOL v4 (if possible 4.1 while 4.0 is rather limited and far more difficult to tweak in the solver section, it's was a too-early version)

for that
a) you apply your voltage in a stationary case to stress your beam,
b) you store the solution, and
c) you do an eigenfrequency analysis taking the stored solution as linearizion point

--
Good luck
Ivar

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