Merging surfaces..

Altair Forum User

Hi,

I want to know whether it is possible to merge or equivalence two surfaces(which are 20 mm apart) in Hypermesh. If so, I would be grateful to know how it could be done..

Thanks...

Altair Forum User

You can equivalence the edges, then check for duplicate surfaces. The cleanup tolerance needs to be bigger than 20 mm though, so if your surfaces are on the order of that size, this is not a good idea. Translating first might help.

Altair Forum User

Actually the FE model was created by doing midsurface of the imported Step file from Catia. One of the sub task is that I have to actually join two plate surfaces in a rigid manner. After the midsurface was executed, the distance between the two plates became very wide. When I tried using rigid connectors, it is failing when i solve in Nastran. That's why I asked for any suitable method to merge those surfaces..

Thanks in advance..

Altair Forum User

This is not clear. Are you connecting elements or surfaces?

Altair Forum User

Ok, this is it. Initially there was a distance between two plates. They should have been connected together using bolt joints(there are holes on the surface for fastening and it is the actual physical case). But I was not worried about the joint modelling of bolts, so I now want to create a surface to surface contact(in physical terms). I have meshed both the components, but since there is a very big gap between the two components, I was not sure how to equivalence/merge them inorder to create a link between them. I tried area connectors, bolt connectors, spot, seam etc initially but all of them failed while solving in nastran. Now I do not want any type of connection between them. I just want the two surfaces to be rigidly connected to each other. Am I clear? If you want anything specific, please tell me, I can give more info.

Altair Forum User

And rigid elements are not working for you? Or a bolt w/spider with a Beam element for the bolt?

Altair Forum User

No they ain't working. Nastran says the nodes are not properly constrained, but actually the nodes are properly constrained.. I suspect that the problem is because the two shell elements which are in different orientation, when connected using rigid links don't go together properly. Nevertheless, as u said above I have started to 'translate' the components and equivalence the nodes. Let me see if this method works properly(I hope it will). Any alternative suggestions are kindly welcome.

Thanks..

Altair Forum User

For starters, I would make a rigid spider where the independent node is at the center bolt location and all the nodes at the free edges of both holes are independent nodes. This is also an option in the connectors/bolt panel.

*edit*

You should also check which DOF you are constraining.

Altair Forum User

The one which you said above was tried by me but it failed while solving(and incidentally in the whole structure it was on these independant nodes where I constrained the DOFs). Anyway I will try once again with all combinations possible. Thanks a lot for your kind support.