Strange Reactions

[Engineer3636]

Hi, 

I am trying to design a shell plate with a moment in it but I seem to be getting different reactions than I expect. I then tried it with bar elements and they seem as I would expect and calculate by hand.

Can somone please explain am I doing something wrong.

See link for file please take a look at it.

Thanks.

 https://www.wetransfer.com/downloads/09005c0d455a0a5bac24f74bcea7e81d20141030143503/4d3ddb

[Rafacascudo]

In calculation model use rigid XY diafragm and the results will be equal to the " bars" structure

[Engineer3636]

Thanks Rafacascudo,
But why is the forces so different? I don't understand as the reactions in the original plate don't add up or symmetrical? Does robot not take the the stiffeners into consideration. Any guidance would be appreciated as I am still trying to learn robot.

Also will this give me correct stress in the plate.
This is a splice plate that I am trying to design. The model only shows half the plate it should be 260mm long with similar bolts opposite side. With moment in the middle. I would like to model it all in robot. Which way would you normally do this or should I design plate?

Thanks agin.
D

[Artur.Kosakowski]

The surface elements used in Robot don't have in-plane rotational stiffness. You need to either replace the moment with forces or apply moment but connects the node it is defined in with neighbouring nodes with either dummy bars or rigid links. Mind the support conditions as well.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Engineer3636]

Thanks Artur, This is worked well but wont give the correct stress in the plate. What I really would like is to model the complete splice plate with the moment and shear in both directions at the centre. See attached. Is it possible you could show me how this can be done. Thanks D

[Engineer3636]

attachment

https://www.wetransfer.com/downloads/510cb261969fb9cd2abf6731372b015a20141104141356/74d694

[Artur.Kosakowski]

Perhaps like that (case 1) ?

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Engineer3636]

Artur,

Dont think this is correct. What I would like is to model the plate as shown in the below attachment. My hand calculation works out the stress for case 2 should be approx. 53N/mm2 with steel 6mm thick plate.

I want to work out the stress and forces in the bolts on the plate design. Any ideas?

https://www.wetransfer.com/downloads/df763f8e84ce88205764e4ae125ac82d20141105082304/739a1e

[Engineer3636]

Hi Artur,

Did you get a chance to review my post.

Has anybody else any idea?

Thanks

[t.sautierr · Accepted solution]

This way ? 

Set your values and goemetrical data.

http://we.tl/QRWjb4D3oL