The same connection modeled in two ways gives different results

Hello!

I'm looking for help with understanding why the (seemingly same) 1D-2D connection modeled in two different ways gives dramatically different results (30% difference). I have a plate modeled with shell elements and a beam. Two variants of connection are described on the picture below. I'd be grateful for your assistance. Why are the results different?

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HyperMesh

v2022

Accepted answers

PaulAltair

In Case V1, you are coupling DOF6 at the CBEAM to an RBE2 that only has Translational DOFS coupled back to the hole. In this case I think the rotation of the beam in the hole remains unconstrained in effect since the RBE2 cannot carry that moment.

In Case V2, you have directly coupled DOF6 of the Beam from independent of the RBE2 from one end to the other so I think moment between Beam and Hole will be carried.

If you add DOF6 to the RBE2 in Case V1 does it give same/similar then to V2?

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PaulAltair

In Case V2, you have directly coupled DOF6 of the Beam from independent of the RBE2 from one end to the other so I think moment between Beam and Hole will be carried.

If you add DOF6 to the RBE2 in Case V1 does it give same/similar then to V2?

Rafał Szypulski_22596

In Case V1, you are coupling DOF6 at the CBEAM to an RBE2 that only has Translational DOFS coupled back to the hole. In this case I think the rotation of the beam in the hole remains unconstrained in effect since the RBE2 cannot carry that moment.

In Case V2, you have directly coupled DOF6 of the Beam from independent of the RBE2 from one end to the other so I think moment between Beam and Hole will be carried.

If you add DOF6 to the RBE2 in Case V1 does it give same/similar then to V2?

Of course... The outcome is the same. Thank you, yet once again!