Superelement can be copied?

[Lirock]

Hi,everyone:
In substructure application, how to creat superelements at different positions? Can it be copied like other normal element?

 

[cbrn]

Hi,
yes, it can be instanced (SETRAN / SESYMM). There are some important hints as regards loads etc, as they are expressed in the superelement's coordinate system, which will be rotated / traslated in the instances: these aspects are described in the Help, Chapter 10 of the Advanced Guide.

Hope this helps.

Regards

 

[Lirock]

Hi,cbrn:
It looks like that if there are no rotated nodes, SESYMM works well, but if there are some rotated nodes in the superelement, SESYMM doesn't work.
For SETRAN, if rotated nodes included in the superelement,it creats the new superelement at the same position. I don't know how to copy a superelement with rotated nodes.
Thank you for your first answer.
Rock Li

 

[cbrn]

Hi,
I still haven't tried the SETRAN method, because right now I'm trying to substructure a system using the top-down method (because the full system, meshed, fits in memory; it's only too heavy to perform a transient analysis with), not the bottom-up method as in your case.
I believe that, when defining the superelement, ALL its nodes must be rotated to the same ESYS. This makes sense if we think about the meaning of "superelement": it's a matrix whose coefficients must be referred to an element coordinate system, but if some nodes of the substructured part are rotated in different coord sys, there can be mismatches or unpredicted results.
Remember that SETRAN only creates the new superelement by re-attributing it to a new ESYS, or by adding an offset matrix transformation to the superelement matrix, or both. You still have to use SE to read it in the use pass.
If you find that the new superelement is not in the position you expected it to be, probably you missed the offset transformation. In fact, I suppose that the coord sys reattribution is just like when you EMODIF some elements to have a new ESYS, but it doesn't shift the node locations; in addition, setting SETRAN's NOROT key to 0 seems like issueing a NROTAT,all in the new coord sys for all the nodes of the superelement (that's why the superelement matrices are unchanged). Only suppositions, though, as I haven't tried it yet (and supposedly won't try it for a while !... ;-) since I still have to finish my investigations on the top-down substructuring... I'm a beginner in that field...)

Hope this helps in some way.

Regards