Ram Elements merging models with shell elements

I created 4 models out of shell elements primarily and I want to merge them together.  I have moved the node coordinates of each model separately so that they are in the correct geometrical position to be merged.

1. Should I renumber the nodes, shells and members to avoid overwriting and losing these elements?

2.  For plates (for example: bent plate flanges) that mate or partially mate with the plates of the adjacent model, should the node numbers for the corresponding nodes match if they occupy the same coordinates?  I assume that this will become a fixed connection in the merged model. True?

3. For plates that mate in the same plane but the nodes are not in the same position,  Will Ram mesh the portion of the plates that overlap in a similar pattern such that the FEM nodes are shared or connected?

4. Most of the 4 models are constructed with 1/4" plate and bent plate.  There are a few plate stiffeners made from small HSS square tubes.The stiffeners have nodes within the plane of the shell elements but not necessarily at the outer edge of the shell it is attached to or welded.  Also, I set the cardinal points of the stiffeners to correspond to the plane of the shell element.  Will these stiffeners behave the way I am thinking they should?

  • From your example, nodes with the same coordinates as Nodes 5,7,9,10 should be present in both models before merging.  Beam elements should be present in one of the models and they should be connected between these nodes. As shown above, 3 beams would mesh and connect the plates on 3 sides.  A 4th beam would connect the plates on the 4th side (N9-N10).

    For a beam element to be meshed with a shell element, the nodes at each end of a beam must be listed in the definition of that shell.  Or the beam must be connected to another beam that is being meshed with the shell as the beams in your example connect to N5 and N7.

    Did I get it right?  I won't need to have a thicker plate. A good connection (weld) around the perimeter intersection is all I need.  However, it looks like I need to do some more work before I do any merging!

  • It looks like the 4th beam N9-N10 is not required to mesh and connect or "weld"  the two plates together.  I think that it meshes because the edge of the left plate cuts completely across the right plate.  But the edges of the right plate do not cut completely across the left plate, so beam elements are needed to make the meshing and connections work.  I'm not sure why exactly this is true.

    Seth, could jump in, look at these 2 last posts and straighten me out?

  • A beam from N9 to N10 would not hurt.  My sample mesh was very large and it comes out rectangular, so it could be a coincidence that the mesh is a straight line from N9 to N10. 

    If you are merging models then they don't both need members in these location, one model or the other will do. Duplicate members should get purged on import/merge anyway. 



  • I un-selected one of the shells, looked at the FEM nodes along the line from N9 to N10 and they matched the nodes along the same line for the other shell.  I did this for a couple of different mesh sizes with the same results.

    From my 1:15 post, I also discovered that I don't need the unattached interior nodes on one shell to match up to the nodes with the beams on the other shell.  The merge worked well without them.

    Experimenting!  So I am not entirely sure why it works or if it always works this way.