topic Re: Moment Transfer Through Rigid Link in Robot Structural Analysis Forum

Moment Transfer Through Rigid Link

Anonymous — Tue, 16 Jan 2018 13:57:04 GMT

I've included an image, below, which should be clear enough for the question. Any thoughts on what may be happening here? Happy to share the model with anyone who asks for it.

I should note: the bottom of the lower bar is the same section as above the rigid link, and it's fixed at the bottom. Above the rigid link is a cantilever; so effectively we have a backpropped cantilever. Both the cantilever and the backpropped section are the same length. I would expect moment continuity, beyond where we have the 9.07 kN.m result...

Re: Moment Transfer Through Rigid Link

Artur.Kosakowski — Tue, 16 Jan 2018 14:01:59 GMT

Hi @Anonymous

Assuming that the master node is in the center try to replace the rigid links with rigid bar elements with RXRYRZ releases at their 'outer' nodes as it will be easier to see what actually happens.

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Re: Moment Transfer Through Rigid Link

Anonymous — Tue, 16 Jan 2018 14:17:30 GMT

Thanks Artur,

That does in fact give me the result I expected -- I connected the central post with the 4 corners using sections that were much stiffer than the other elements. I thought that's what the Rigid Link was effectively doing when I released the rotational components, so I'm not sure I understand what was happening there. Is there an explanation for that?

Re: Moment Transfer Through Rigid Link

Artur.Kosakowski — Tue, 16 Jan 2018 14:33:17 GMT

Hi @Anonymous

Could you attach your model?

Re: Moment Transfer Through Rigid Link

Artur.Kosakowski — Tue, 16 Jan 2018 15:57:18 GMT

Hi @Anonymous

The rigid links you described correspond to the definition of releases as shown below:

See:

http://help.autodesk.com/view/RSAPRO/2018/ENU/?guid=GUID-88C4C842-5D90-4E85-8F8C-D47D6E474E29

For the releases on both ends as you defined them in your bar model the vertical bar would require UZ and RZ support at its bottom (check the deformation for case 1)

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