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3D Indenter Problem

3D Indenter Problem

3D Indenter Problem

(OP)
I am trying to model an AFM tip pressing down on the center of a circular membrane. The AFM indenter is an analytical sphere and the membrane is clamped around the perimeter. These parts have surface-to-surface contact. I am applying a displacement to the AFM tip.

My problem is that I am getting the following warnings that ultimately result in an error:

***WARNING: THE SYSTEM MATRIX HAS 31081 NEGATIVE EIGENVALUES.
***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE
MEMBRANE-1.3306 D.O.F. 1 RATIO = 310.855E+09 .

The nodes it gives error messages for are actually usually half way in between the edges and the center of the circle.

Any Suggestions?

RE: 3D Indenter Problem

If you upload the CAE file you may get more help.

Is your model axisymmetric, implicit?

Hopefully I'll be more help later.

Rob

Thank you.

Rob Stupplebeen
OptimalDevice.com
My Personal WP

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