Connecting 2D and 3D elements of a same structural element

Altair Forum User

I am trying this normal mode analysis for an assembly with 4 small bone kind of structures by welding. Since there is a porting of 1 mm thick I made it as 2D elements. But I couldn't get the connectivity between the 3D elements and 2D elements, which results frequencies of the order of 10^-3 and all.

 

I checked and done equivalence and all. But still its not working.

 

Can someone help me in solving this issue. Thanks in advance.

 

Note: I can't attach the file here, since size is limited. I am free to share the file.

Altair Forum User

Hi Natarajan,

 

you can't connect 2D shells to 3D solids without any additional action.

3D solids have only 3 DOFs at every node, so no rotational degrees of freedom are transferred. If you are attaching a shell to solid, then the shell can rotate about the connection.

 

A simple way is to add a additional row of shell elements into the solid or at the surface area (i'm using the row into the solid, the shell thickness can be a little smaller but you have to check it).

There are a lot of other ways (RBE2, RBE3, Beams...) you have to search your own. At all, the local connection is difficult to evaluate.

 

For eigenfrequencies you can supress the low frequencies by the parameter V1 at the EIGRL card (e.g. 0.1 to supress the rigid body modes in free-free analysis)

 

 

Regards,

Mario

Altair Forum User

Thanks Mario.