Finding unintended cracks in mesh

I was astonished that there was an unintentional "crack" in the mesh in this discussion.

The mesh had Node Merge applied in the Mesh Edit branch so I expected that the nodes were merged, but clearly they were not. This was revealed only after the solution was examined carefully with the deformation contour plot.

How can these unintentional "cracks" in the mesh be found before the solver starts on them?

SIEMENS NX has a way to display the "free" edges of the mesh. Here is a mesh before the node merge.

Here is the display just after the merge node command. It is easy to see before the solver starts that this mesh has a crack.

Here is the "free edge" display in case you missed the display above. It is easy to see before the solver starts that this mesh has a crack.

Below is the "free edge" display after loosening the Node Merge tolerance.  Now there is no crack.

How can I see if there are unintentional "cracks" in an ANSYS mesh before the solver works on it?

Comments

  • peteroznewmanpeteroznewman Member
    edited June 2018

    One method available in ANSYS to know if all the nodes on a face were merged is to count the nodes on the face. I have used the box select tool with the Node filter to draw a box around a face. The number of nodes on that face is shown in the bottom of the Mechanical window and is 69.  An Info message in the Messages window tells me that only 32 nodes were merged, so that is one way to know that there is a crack in the model. After loosening the tolerance in Node Merge, I can confirm that all 69 nodes were merged.

      

     

    The problem with the Info message is that the Messages can be deleted.

    How can the crack be discovered after the message is gone? 

    An ANSYS 18.2 archive is attached for anyone who wants to try this out for themselves.

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