Here's another issue I'm having with bonded contact sets and beams.
PROBLEM 1:
I have the following model:
And have created BONDED contact between the two SOLID bodies and a BONDED contact between BEAM structure/Solid face:
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).
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)
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:
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:
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:
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?
Here's another avenue I've gone down in the search for a solution to this problem. This appears to provide reasonable results (until someone can counter this as inaccurate, wink, wink).
I have treated the large cylinder and the cylindrical interface as Solids, while the truss is treated as a Beam. Instead of mating the cut faces of the truss elements directly to the face of the cylindrical interface, I have instead constrained it by origin planes. Then, I modified the Truss so the circular extrusion cut (23.25") is slightly larger than the diameter of the cylindrical interface (d = 23"). This creates a physical 1/8" gap between the truss and the interface (which allows spacing so Joints do not lay within a solid). There are two more solid components mated to the beam truss as well, these also have a 1/8" gap. (Basically, I included the gap between solids and beam elements that show the green Joint, representing a beam joint that is not connect to another structural member)
The curvature based meshed is used and when the model is ran in Simulation a notification pops up:
All I think this warning is stating is that the solver automatically changes the meshing to handle the physical gap between components...
The solution runs just fine after that and all the displacements as well as all the stresses seem to be correct. Let me know if you have any responses/suggestions...
Thanks!!