Problem with plastic deformation (Plateau) in 2D model 3

[Algirdas13]

Hey everyone,

I'm facing a problem with non-linear analysis using shell elements. The software is Nastran in CAD (Autodesk Inventor Add-in).
I did a simple analysis of the lifting lug by using 3D solid elements (parabolic order) and bi-linear material (LGDISP is on). The model performed pretty well and managed to reach the plateau (plastic deformation).
After that I tried to do the exactly same simulation but using 2D shell elements (parabolic order), bi-linear material (LGDISP is on). In such case during the analysis a plateau (plastic deformation) wasn't reached. Solver managed only capture the elastic-plastic transition and then stopped because of calculations resulting in divergency.

For both analysis I used same parameters, material properties and force. For 2D calculation I also tried to increase number of increments.
Maybe someone could help me out to figure out or share some insights what I did wrong in analysis where I used shell elements?

P.S. these calculations are not meant to determine capacity of lifting lug but rather to learn how to perform a non-linear analysis and see the correlation regarding the hand calculations.

Shell setup:

Solid setup:

 

[dik]

why would you use such a fine mesh for anything beyond the actual hole?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SWComposites]

If those are linear tet elements (4 nodes), the are awful and should not be used. Use hex elements or 10 noded tets.
If you are designing real lugs, you should be designing to codes, or have test data to which you can correlate the FEMs. Lug strength is way more complicated than it appears, and there are a large number of potentially critical failure modes, in the lugs and the pin. Please do not rely solely on FEA.