Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Error 7111: Singular matrix

Please login with a confirmed email address before reporting spam

Hi all,

I'm trying to solve a simple hyperelastic cube (Neo-Hookean) that contains two hyperelastic fibers.
I'm using a 3D Structural mechanics - Solid, Stress-Strain module.

1) At first,
a) I applied one set of periodic boundary conditions from one face of the cube to the opposite face.
b) Then I added constraints on 3 points (using "point settings").
c) and I added constraints on the all remaining boundaries (using "boundary settings").
This one worked!

2) However, when I chose two more (opposite) faces and applied one more set of periodic boundary conditions on them (instead of the boundary constraints that were applied on them in the last case), I received the following error:

Error 7111: Singular matrix

Details:
Exception:
com.femlab.jni.FlNativeException: Singular matrix
Messages:
Singular matrix

Stack trace:
at umfpack.cpp, row 597, ()
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)

3) The periodic boundary conditions are supposed to be correct - I'll explain: When I used a simple cube- without the fibers and applied both sets of periodic boundary conditions on 4 faces plus adding constraints on 3 points - this was solved! The error occurs only when adding the fibers... Is this a meshing problem?

What do you suggest I should do in this case?

Thank you in advance,
Tal

1 Reply Last Post 24 avr. 2010, 07:56 UTC−4

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 24 avr. 2010, 07:56 UTC−4
I don't know if it helps, but for periodic boundary conditions you should have an exact mesh of the source on the clone boundary, and you can acheive this by copying the meshes between the boundaries.
I don't know if it helps, but for periodic boundary conditions you should have an exact mesh of the source on the clone boundary, and you can acheive this by copying the meshes between the boundaries.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.