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Attaching beam to surface (edit: coupling beam and structural mechanics)

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Hi all,

I asked a similar question recently, but I have another question about working with beams.

I am trying to make this object swing using these beams to hold it up. I have made some beams, drawn points at the tops and bottoms of the beams, pinned the top points in place, and put part of the object's surface incident with the bottom points. There is gravity and a force pushing the object.

Edit: I have learned that the beam and structural mechanics physics are not coupled, and I need to couple these. However, I have no multiphysics node or option that I can find. Is there a way to couple these two physics? Thanks!

I have attached the file if you wouldn't mind taking a look. Thanks so much!


2 Replies Last Post 2 juil. 2014, 04:13 UTC−4
Henrik Sönnerlind COMSOL Employee

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Posted: 1 decade ago 2 juil. 2014, 03:56 UTC−4
Hi,

The quickest method is to rename the displacement field in the Solid Mechanics interface from 'u2' to 'u', This will make the displacement degrees of freedom to be the same in both physics interfaces.

You can do that in the Dependent Variables section in the Solid Mechanics node.

Since the connection is at a point, it will act as a ball joint. The stresses in the solid may be locally large at the connection point, since it is a singularity there.

Regards,
Henrik
Hi, The quickest method is to rename the displacement field in the Solid Mechanics interface from 'u2' to 'u', This will make the displacement degrees of freedom to be the same in both physics interfaces. You can do that in the Dependent Variables section in the Solid Mechanics node. Since the connection is at a point, it will act as a ball joint. The stresses in the solid may be locally large at the connection point, since it is a singularity there. Regards, Henrik

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Posted: 1 decade ago 2 juil. 2014, 04:13 UTC−4
Hi Henrik,

Thanks for the response! I have actually tried this since posting the thread, but when I compute, the body still falls as if it is not attached. I have tried increasing the density and Young's modulus of the beam, in case it was just breaking, but the body still falls as if the two are not attached.

I can get tension in the beam even without an edge load, so it must know that the body is there, but they do not stay together. Any thoughts on this?

Thanks!
Hi Henrik, Thanks for the response! I have actually tried this since posting the thread, but when I compute, the body still falls as if it is not attached. I have tried increasing the density and Young's modulus of the beam, in case it was just breaking, but the body still falls as if the two are not attached. I can get tension in the beam even without an edge load, so it must know that the body is there, but they do not stay together. Any thoughts on this? Thanks!

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