You may find that you've the wrong mesh density at different parts of the
structure. In addition you may of modeled to much of the device.  If it is
symmetric you will only need to model the section about the line of
symmetry. Don't forget that you can only use mapped meshing for uniformed
area/volumes.
The best FEA book (I've found) is by MJ Fagan: FEA Theory & Practice.
How are you assembling the model? You should try creating a *.log file.
 You can then alter different aspects of the device to find errors.
With all FEA models you should validate the results by modeling a simple
device that you can pre-calculate.  Examples of diaphragms are given in the
above reference.

Trevor Niblock;
MEMS group, Rm. 2043, Building 53, ECS, Southampton University,
Highfield, Southampton, SO17 1BJ, UK.
e-mail: [email protected]
URL:    http://www.mems.ecs.soton.ac.uk/users/trevor/tn_hp.htm
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-----Original Message-----
From:   [email protected] [SMTP:[email protected]]
Sent:   26 January 1999 10:41
To:     [email protected]
Subject:        Re: High Frequency Transducers


Dear MEMS Researchers,

I am currently in the process of using ANSYS FEA S/W to model a
pressure sensor's membrane. I have just created the structure of the
whole sensor, and found out that I have difficulty in mashing it. May I
know the reasons?

Also can anyone point me to anywhere where I can get some reference or
result regarding this tropic, so that I could use it as my reference.

Very Much Thanks in advance for any advice!

AJ Pang



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Heriot-Watt University