SimScale CAE Forum

Non-linear analysis


#1

I’m trying to do a non-linear analysis, should I put the materials behavior as plastic? The materials don’t have to yield!
Running the simulation this is the error: “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”


#2

Hi @srenda!

Is this a follow up question to the other thread you opened? If so make sure to keep things in place and do not open new posts as this might be confusing for us to answer. Feel free to share your project here, the message you got is quite common and you can find some information on that in the forum.

Once you shared the project we can make some suggestions on how to optimize your simulation.

Cheers,

Jousef


#3

Yes. Sorry. It concerns the same topic.
https://www.simscale.com/workbench/?pid=4469405883328340836&mi=run%3A2%2Csimulation%3A7&mt=SIMULATION_RUN
This is the project if it helps you to unserstand. What I have to do is to fix the so called infinite plate and apply a force along the negative y of 100 N on the screw in the steel plate, but the problems I shared pop up and I can’t fix it. The simulation is a non-linear analysis as I said.


#4

You say you are not interested in post yield behavior, so could you explain why you say you need to do a non-linear study?


#5

Because if I do a linear analysis the value of displacement that I obtain are not coherent with the real test done in the laboratory, but I don’ know why


#6

Hi @srenda,

I just took a quick look at your project but it appears your linear solutions use a first order mesh. You should try this with a second order mesh and see if the results are closer to what you expect.

I’ll look some more at it this afternoon.
Christopher


#7

Hello again @srenda,

I took a little longer look at your model and I have a created a project with work physical contacts.

Working Physical Contacts

I re-created your project setup so some of the values may not be the same as you were using. For example this project uses the penalty method for contact simply because that was the default. You should be able to change this without a problem,

The two main issues I saw was the force was a function of Y not time and the and the piece of steel that formed the 90 was not constrained.

Please take a look at this and let me know if you have any further questions.

Good Luck,
Christopher


#9

Thanks for your help, but looking at your simulation, it doesn’t show any displacement (which is the information I need). How is it possible?
And also, why did you make a dynamic simulation and not a static one?


#10

Hi @srenda!

It does show the displacement, go to the “last step” in the post-processor and you will see the displacements :slight_smile:

Let us know if you have any other questions!

Jousef


#11

Ok found it!
By the way, thanks a lot, this forum is helping me so much!!!


#12

You’re welcome @srenda! :slight_smile:

Best,

Jousef


#13

Sorry, I have to ask another thing.
How do I solve this problem:“The machine ran out of memory. Please choose a larger machine by increasing the number of computing cores or reduce the fineness of your mesh.” I tried to reducer to size of the mesh, but that didn’t work. Are there any other way?


#14

Reducing the number of volumes/faces in the mesh (try even fewer volumes/faces) should work for that message (or increase your number of cores)…


#15

Hi @srenda,

The dynamic analysis was done just to help me debug the static analysis. It can be ignored.

Under Simulation Controls you can increase the number of processors to be allocated more memory.

Christopher