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Merge nodes deletes hex mesh on entire solid

Genius
Genius

When I merge the nodes on this model, FEMAP deletes the entire hex mesh on Solid 5. I've tried rebuilding the database, restarting FEMAP, and repeatedly remeshing (analyst's equivalent of banging one's head against a wall). Every time I merge all nodes in the model it deletes this portion of the mesh again.

 

Please help.

 

*Update: I just deleted the mesh by type 25, remeshed (hex) all solids and then the node merge operation worked as expected. I would still be interested to know if the attached model could be used to improve the current FEMAP behavior, or if I did something wrong. I suspect doubled elements (the element count is high), but am confused why that would lead to deletion of the mesh on a solid.

1 REPLY

Re: Merge nodes deletes hex mesh on entire solid

Siemens Phenom Siemens Phenom
Siemens Phenom

Actually the problem is that you have duplicated coincident elements on Solid 5. With standard graphics FEMAP displays, and a filled display like you have, only the free-faces of solids are displayed. Prior to merging your nodes, each element had its own nodes so technically the exterior faces of each were "free". After you merged the nodes, the faces from both used the same nodes, so they weren't considered "free" and those elements disappeared. 

 

Obviously you probably don't want the duplicate elements so simply deleting one set will solve the problem. However, there are a number of ways to see them even when they are duplicated

  • Turn off Fill
  • Turn on Shrink
  • Switch to Performance Graphics ... The free face algorithm in Performance Graphics has been improved to recognize that the normals to both faces are pointing in the same direction and therefore the faces are really still "free"

Hope this helps.