Help with static non-linear error "The solution matrix is singular...."

Project Support
1

Here is a link to my project:
[Deleted by author]

This is my first attempt to use SimScale and my goal is simply to deform a part and measure the total strain.

I have followed the “Aluminum pipe bending” tutorial, and I tried to set my simulation up using the same approach. I 've spent about a day and a half trying to work through this by tweaking boundary conditions, contact settings, material settings, numerical settings (tried most of the different direct and indirect solvers) and geometry, but I cannot get this simulation to solve.

This is the error I’m getting:

  • The solution matrix is singular. This may be caused by an unconstrained rigid body motion, a physical contact definition with open gap in a nonlinear static analysis or incoherent material parameters

I believe all my bodies are properly constrained, and there is no gap between parts (line to line contact). My material parameters were taken from a true S-S curve of nitinol wire, and I believe I’ve input things correctly. I’m really not sure where I’ve gone wrong here, so hoping someone who is an expert in SimScale might be able to help me figure this out.

Here is an image illustrating what I want to do. I simply want to deform the part like shown and measure the total strain.

Goal
Goal590×621 47.6 KB

2

Hey @ssoeder1!

I saw that your third run was successful but from what you have shown I would assume that you have to change the table input as your structure is somehow showing a buckling phenomenon and you want to only bend it, correct? Tagging the @fea_squad for more input here.

Best,

Jousef

3

Hi Josefm,

One of the SimScale support staff was able to help me by making some adjustments to my project. After interrogating his copy of my project, I discover that getting rid of the “symmetry plane” boundary condition and replacing it with a static value condition with the sectioned face fixed in the Z plane only allowed the project to solve.

I’m not sure why the symmetry plane was an issue here, but by comparing his simulation to my original one which would not solve, and going through all of his changes one by one, process of elimination showed this was the one change that was needed to get the problem to solve.

4

Thanks for the clarification :slight_smile:

I added comments like that one regarding symmetry and the displacement BC in some forum posts but I think yours is emphasizing even more to get a knowledge base article about that in our doc! A good explanation from my colleague Richard can be found here: Pin - the problem with contacts - #6 by rszoeke

Best,

Jousef