AnsweredAssumed Answered

Beam Contact Set FAIL

Question asked by Daniel Kitts on Aug 13, 2013
Latest reply on Aug 22, 2013 by Daniel Kitts

Here's another issue I'm having with bonded contact sets and beams. 

 

PROBLEM 1:

 

I have the following model:

 

 

Help_1.png

And have created BONDED contact between the two SOLID bodies and a BONDED contact between BEAM structure/Solid face:

Help_1a contact sets.png

I'm trying to see my stresses in all beam components, for now just running gravity as the only external force and have the large cylindrical beam fixed on it's top joint (0 translation about X, Y, and Z, zero rotation about Y, Y is the UP direcion in these pictures) and fixture on bottom joint (0 translation in X and Z).

Help_1b fixtures.png

When I initially mesh this configuration, I get a huge gap between the two cylindrical beams at the left end of the truss structure (one beam is a full pipe, the other is a cut cylinder constrained to the face of the tube)

Help_2 initial mesh problem.png

How do I implement a contact here?  (Both of these are beam elements, so I cannot create a contact to either face)

 

PROBLEM 2:

 

Now, to try and get around the "gap" error above, I will treat the larger beam as a solid (now I'll have the ability to create a contact set to the face).  I updated the "Joint group", the component contacts, and updated the fixtures.  I created a new component contact between the large cylinder face and the cut cylindrical beam:

 

Help_3 BasSol, contact.png

 

I now must refine the mesh to handle the new solid component. I select a curvature based mesh and it handles the new geometry just fine:

Help_4 BasSol, curvature mesh.pngHelp_4a BasSol, curvature mesh.png

Everything looks peachy with the mest, the beam components (cut cylinder) appears to be contacted to the outer face of the large solid cylinder.

 

 

However, once the simulation runs, the solution is messed up.  It seems that the interface between the beam and solid cylinder are not in place.  The stresses that are imposed on the beam frame do not translate into the solid cylinder.  From the displacement, it appears that the bottom beam actually penetrates the solid cylinder, but only near the bottom:

 

Help_5 Solution is wrong.png

I attached a video of the animated stress plot in the beam elements and an animation of the displacement plot (it's easy to see that the contact set between the beam and solid cylinder has no effect on stiffening the truss...it's as if the truss is only attached by the top joint). 

 

Does anyone know why the bottom joint appears to be completely free and moving through the solid?

 

 

 

 

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