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Inverted Mesh problem

Posted Apr 11, 2011, 4:53 p.m. EDT 1 Reply

Doyoung Kim
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I designed MEMS Pillar which is as vertical shape of MEMS cantilever with COMSOL 3.5a version. The design is very similar to sample cantilever that is offered from COMSOL. I used Silicon for the beam instead of Polysilicon with Aluminum above Silicon. I followed the exact tutorial and got a problem with "Inverted Mesh". The error is as follow:

***************************************************************************************************************************************
Error: 7248
Undefined value found.
***************************************************************************************************************************************
Detail:

Exception:
com.femlab.jni.FlNativeException: Undefined value found Solvermodel
Messages:
Undefined value found Solvermodel

Stack trace:
at solvermodel.cpp, row 1837, (Undefined value found in the equation residual vector.
There are 27 degrees of freedom giving NaN/Inf in the vector for the variable u
at coordinates: (2e-006,0.00032625), (2e-006,0.000328125), (2e-006,0.00033), (2e-006,0.000331875), (2e-006,0.00033375), ...
There are 27 degrees of freedom giving NaN/Inf in the vector for the variable v
at coordinates: (2e-006,0.00032625), (2e-006,0.000328125), (2e-006,0.00033), (2e-006,0.000331875), (2e-006,0.00033375), ...
)
at com.femlab.solver.FlSolver.femStatic(Native Method)
at com.femlab.solver.FemStatic.run(Unknown Source)
at com.femlab.server.FlRunner.run(Unknown Source)
at com.femlab.util.i.run(Unknown Source)
at com.femlab.util.aa.run(Unknown Source)

***************************************************************************************************************************************
Progress - Solve Problem
Warning: Inverted mesh element near coordinates (0, 0)
***************************************************************************************************************************************

Please simulate the design after download the attached file below and let me know where I should fix the model.

Thank you for your consideration.

Sincerely,

Doyoung Kim


Attachments:

1 Reply Last Post Apr 12, 2011, 1:41 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 12, 2011, 1:41 a.m. EDT
Hi
the inverted mesh info is a warning, not per say an error, you have something else, such as a missing BC or not many enough BC's in your model, which is giving your the NaN's

Try to solve one physics at the time to identify what is wrong, I had a quick glance, but did not see it, on the other hands 3.5 is old so I'm no longer that sharp to point out the hidden errors any longer

--
Good luck
Ivar
Hi the inverted mesh info is a warning, not per say an error, you have something else, such as a missing BC or not many enough BC's in your model, which is giving your the NaN's Try to solve one physics at the time to identify what is wrong, I had a quick glance, but did not see it, on the other hands 3.5 is old so I'm no longer that sharp to point out the hidden errors any longer -- Good luck Ivar

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