slow model and E5019 error

[michele_mrc]

Good morning everyone,

I have two problem with the model attacched to this post.

1) I have some nodes connected with rigid connectors where I apply a constraint. The analysis doesn't work and give me E5019 error. To solve the problem I set AUTOFIXRIGIDSPC to ON and the analysis now work. However, I don't think I have understood what this command does. Can someone helph me?

2) The model runs really slow. It is not a big model and I didn't use a fine mesh to try to solve the problem, but it is still slow to run. At the beginning, I used a "global" model, but it was much slower, so I decided to use simmetry constraint: that helph, but doesn't solve the problem. I don't think the problem is whit contacts: even if I remove them, the problem is still there. My idea is that the problem is in the big number of geometric features, connectors and constrain, but it is just an idea. Is it correct?

Whit a slow model, I can't use a finer mesh to obtain a more correct solution.

Thank in advance,

Michele

[benoit.neu-faber]

Bongiorno Michele,

I had a look to your model.

There are several remarks : 

- I would probably have run this as solid elements.

- The way you have modeled the bolts looks strange to me. I would have used bolt connectors for that.

- I don't understand why you have used springs ?

I'm convinced that the error message and the fact that your model is slow is because of the modelling technic that is used.

Best Regards

Benoit Neu-Faber

INNOSIM https://servicesmarketplace.autodesk.com/provider/public/innosim

Autodesk Service Provider / Nastran Trainer

https://www.linkedin.com/in/benoit-neu-faber/

Please accept solution and give likes if applicable

[michele_mrc]

Thank you very much!

Why should I use solid elements? They need finer mesh to converge the solution.. if I have a plate subjected to bending, I need a lot of solid elements in the thickness, and the analysis should be slower. Isn't it right? In my opinion, this is a shell problem, not a solid problem, but I could be wrong, I'm still learning the art of FEM.

About the bolts: I used frame element to take into account the nonlinearity of the material of the bolts (maybe I should use beams and not bars). And I connected the bolts to the plates with rigid elements.. I know it's a common method. Does the bolt connectors take into account the nonlinear material? And can I use the holes edge to define the bolt connectors (using countinous mesh) or should I define a surface?

The springs are for the anchors. In my opinion, a rigid constraint is just too rigid and doesn't distribuite the loads correctly (and sometimes in the past I had very big prying force using rigid constraint). I think that taking into account the stiffness of the anchors, you have better results. I know that even IdeaStatica does something like that. But againg, I could be wrong.

If you can help me, it would be super.

Thank!

[jura.tomorad]

Where and how do you set AUTOFIXRIGIDSPC on?

How do you identify where the problem is from "FATAL ERROR E5019: DEPENDENT MPC AT GRID 70026 COMPONENT 1 IS OVER CONSTRAINED?

Thank you in advance for your answer.

[John_Holtz]

Hi @jura.tomorad . Welcome to the Inventor Nastran forum.

This is an old thread, and every model is different (so likely a different solution). In the future, it would be better to create a new forum post for such situations.

For parameters, see Tip 6 in the PDF document attached to my forum post Suggested Reading - Tips and Tricks on the Inventor Nastran forum.

For locating the grid number 70026 that is given in the error message, see Tip 45 in the same document.

John

[jura.tomorad]

Thank you very much for your answer!

Kind regards,
Jura Tomorad