Say I have two parts in Apex, each with one surface that share an edge. When I mesh the two parts, there is no mesh congruency across the shared edge. Can you please explain what is the difference between the following three methods: Create an edge tie along the common edge .. mesh is now congruent (but if I export that out to Patran, there are still two unique node IDs at each node-pair location. I think Apex create RBAR between each node pair when it solves? Glue the two parts together. Mesh is not congruent but uses Contact bodies? Create an edge tie to get the congruent mesh. Export bdf to Patran. Equivalence the monolithic FE model and run in Nastran. In other words, if I glue parts together, why spend time to create edge ties?

Edge Tie versus Glue versus Patran Equivalencing

Say I have two parts in Apex, each with one surface that share an edge. When I mesh the two parts, there is no mesh congruency across the shared edge. Can you please explain what is the difference between the following three methods:

Create an edge tie along the common edge .. mesh is now congruent (but if I export that out to Patran, there are still two unique node IDs at each node-pair location. I think Apex create RBAR between each node pair when it solves?
Glue the two parts together. Mesh is not congruent but uses Contact bodies?
Create an edge tie to get the congruent mesh. Export bdf to Patran. Equivalence the monolithic FE model and run in Nastran.

In other words, if I glue parts together, why spend time to create edge ties?

0 Sanjay Patel over 7 years ago
Hi Daron,

Yes, Edge ties are written with rbar and at the time of export ( file export.. nastran bdf) allows you to choose if you want rbar written or not. Edge tie also makes the mesh on two parts conguent so rbars are crated at each node-pair.

Yes. Apex would allow you to create edge ties and glue them as well. This would be incorrect. Its users responsibility to one or the other.

Yes, this is a valid workflow.

If you glue the parts load path would be different than when using the edge ties. It has to do with level of fidelity and accuracy one can tolerate.
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0 dlibby over 7 years ago

Regarding “level of accuracy” in your last point #4 below, Which is more accurate .. gluing or edge ties?
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0 Sanjay Patel over 7 years ago

Anytime you have discontinuity in modeling/mesh it will introduce the accuracy issues. So, option 3 with congruent equivalenced mesh would be best if it suits your situation.
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