add stiffeners to a shell 1

[veronikavoss]

Hi!

I am modelling a tower with a SHELL 281. It was created by sweeping a line around the y-axis.
What I have now is its middle surface and want to add a stiffener-as an area perpendicular to the tower surface.
I am creating the area but have problems with connecting it to the tower. Can you give me some advice on how to do this?

Thank you for your help!
veronika

 

[ARTran]

Veronika,

I'm assuming by "middle surface" you mean some band of the tower between some y1 and y2.
As for the stiffener; if you're using shell 281 for the tower and stiffener you could add layers to the shell elements to represent the stiffener as being built into tower elements.
If you're building the stiffener as a separate entity, it depends on how this stiffener area is being created:

If you're using a quad element [Solid 185] you can use the contact wizard [ Preprocessor> Modeling> Create> Contact Pair] to create a contact surface.
If you're using perpendicular shell elements for the stiffener, you could use node couplings to fix a band of tower nodes to your stiffener nodes.
CP,NSET,Lab,Node1,Node2,...,NodeN

Odds are you'll use: CP,NEXT,ALL,Node1,Node2,...,NodeN
"Next" will set the next reference number while "All" will constrain all degrees of freedom thus fixing the stiffener to the tower.

Hope that helps,
A. Tran

 

[veronikavoss]

Thank you very much for your help A. Tran!
I am using perpendicular shell elements and tried to follow your suggestion. But I have a problem with the nodes because I have an irregular mesh (I attached a print out). I don't know how to pick the nodes in the tower in order to connect them to the stiffener. Thank you again for your help!

Veronika