Modelling Alluminium panels and stiffness

[rubenwood]

Hi there

I have a structure, image below, that is to be cladded with alluminium sheets.

I am trying to calculate it's dynamic response and I would like the alluminuim cladding to contribiute to the stiffness however I am not interested in the stresses in the sheet itself.

As you can see below I have cladded part of the structure however when I calculate the model it creates a mesh and I end up getting this message (attached) if I clad the whole structure.

If i am not mistaken if I am not interested in the plates stresses then I shouldn't have to create the mesh to apply a stiffness.

I found this dsicussion which seemed to have a solution but amazingly I just couldn't find the "panel calculation model" text box.

http://forums.autodesk.com/t5/Robot-Structural-Analysis/HELP-with-generating-mesh-for-Rigid-Diaphrag...

Can somebody please help.

I have attached my model with no cladding in case it helps.

Thanks

[kyp321 · Accepted solution]

You can access the rigid diaphragm as shown above. The model you attached has no panels defined so could not see the error! please take a screenhot of the error and post just as an 'FYI'! Hope this helps

[kyp321 · Accepted solution]

i just noticed your version of robot! Perhaps that version does not have the rigid D feature

[rubenwood]

Yep my version of robot doesn't have this.

Can you think of another way i could model in the stiffness of the plate?

[Rafal.Gaweda]

If I understood you correctly you want to add some stiffeness to claddings.
Solution with diaphragms is not valid in your case because diaphragms have to be horizontal only (like slabs)
So use ordinary panels (shells) or add rigid links but I do not know if it will not make your structure too stiff.

[rubenwood]

Yes I want to add stiffness to panels.

I have version 21.0.0.2810 of robot so I believe I cannot use the "shells" option.

What do you mean by rigid links?

Thanks

[Rafal.Gaweda]

Shell means ordinary panel(s) with Finite Elements.
For sure available in 21 version.

[rubenwood]

Hi 

Yeah the FE is available in the version i Have (Robot Millenium 21.0.0.2810) 

However if I try and include all the panels I get this message

I can model up to about half my panels by manually splitting the mesh into a 3x3 grid.

Thanks

[rubenwood]

can anyone think of a way of modelling in the stiffness of these plates using this version?

[Rafal.Gaweda]

It means you exceeded number of nodes in Protection.
Open installation report from Authorization Settings(?) application to see limits

Decrease number of FEs generated on panels

[Rafal.Gaweda]

can anyone think of a way of modelling in the stiffness of these plates using this version?

---

For you task mesh panels with 1-2-3 FEs on each panel. Enough to give stiffeness to structure.  

[rubenwood]

Hi

Thanks for the quick reply.

I have been trying for ages to model with just 1-2-3 FE panels but it just doesn't seem to work.

Do I go to "meshing options" - User- 2x2 or 1x1 divisions- ? And then run the calculation?

Thank you

[Rafal.Gaweda · Accepted solution]

[Rafal.Gaweda]

This should help you to create panels fast : http://forums.autodesk.com/t5/Robot-Structural-Analysis/Forcing-mesh-in-Robot/m-p/3854666#M12462

[rubenwood]

managed in the end thank you...you've sorted me out.