Mesh error problem

I made U-Type shape aluminium material stamping nonlinear analysis.

Before finish analysis, mesh has error like below figure.

I don’t know how to solve it.
If possible ,could you give me advise ?

-----Material Setting----------

Density 2.7E-09
Young modulus 69000MPa
Poisson’s ratio 0.33
Yield sterss Plastic strain
183 0
2450 0.2

—Surface behavior----
Type Linear
K 30000 N/mm2
Co Deault

— My code (Condition part only ) –

PW : JfaBSxW7uZ

Can you share the whole input file or .pmx file ? Even in private message if you don’t want to make it public. It will be hard (if not impossible) to help without it.

Thank you very much for your message.

I found uploader site.
If possible, could you download and check my pmx code ?

Download PW: prepomax

I have not solved this mesh problem for many years by myself.

I would like to change parameter as follows

– Surface behavior –
K value 60,000 Min (from 30,0000 to 60,000 Min N/mm2 )

–Yield stress Plastic strain–
183 0
1,300 (from 2,450 to 1300 ) 0.2

First of all, assign the rigid body constraints to the whole parts instead of just their surfaces to make tools entirely rigid. In the case of a die you will also have to change the region of a fixed BC to the reference point. Then try refining the mesh of the stripper plate. You may also have to refine this region of the blank:

It seems that there are problems with mesh transition in this area.

Also, have you tried solving this problem with the explicit dynamics step ?

Using a smoother shape of the material yield stress - plastic strain curve instead of a bi-linear curve might also help with the convergence.

FEAnalyst san, Matej san,

Thank you very much for your kindly message!!!
I tried analysis again.
But i had mesh error again…
If possible ,could you confirm uploaded file ?

Also, have you tried solving this problem with the explicit dynamics step ?

I don’t know how to select “explicit dynamics step” on PrePoMax.
If possible ,could you let me know how to select it ?

Remark: I use Mega storage first time. If you cannot download my file, could you let me know it ?

I downloaded the files without any issues. I would recommend Google Drive or Dropbox for storage since the files don’t disappear there after some time (which is often a problem in case of forums) but this one is also fine.

What I would still improve:

  • rigid body constraints should be applied to whole parts, as I’ve mentioned before (just switch the selection mode to Part)
  • refine also the mesh of the stripper plate - it’s very coarse now

The explicit dynamics step is not implemented in PrePoMax yet but you can define it using keywords. Check the CalculiX user’s manual for the *Dynamic keyword: http://www.dhondt.de/ccx_2.19.pdf

FEAnalyst san,

Thank you very much for your reply!!

Is “rigid body constraints should be applied to whole parts” attached photo setting stage ?
If so , i cannot select part.

You have to switch to part selection here:

body, table, td, th, h1, h2, h3 { font-family: Arial, sans-serif !important; }

Dear FEAnalyst san,

Thank you for your kindly reply!

If possible, could you let me know which is best on “Set selection” ?

Surfaces,edges and vertices
Part
Edge angle
Surface angle

It depends on what you want to select. Usually, the first option is enough if your selection is based on geometry.

Dear FEAnalyst san,

Thank you for your message many times!

I had mesh error again.

Is “Static Analysis” difficulty with finishing analysis ?

I tested Dynamic analysis as follows.
But it was failure…

*Step, Nlgeom, Inc=10000
*DYNAMIC,ALPHA=0,SOLVER=SPOOLES
1.E-2,1,1.E-30,1.E-4