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Rigid body

Hello Everyone

I am trying to tensile test analysis and for that I have made a dogbone shape in CATIA and then exported it to Optistruct. In the attached file, you can see that I have partioned it into several solids and then meshed it. Now I want to select the top part of the dogbone on one of the side (cubical shape) and make a rigid. So I created a node in the middle of the top part so that I can apply the loads there.Then I tried to create rigid using 'Geom>rbe3>independent node(by geom)>solids'. I selected the top solid, but it only creates node on one of the surface. I want all the nodes in that solid to be sected so that I can create the rigid.

I have attached the screenshot to make it clear and also attached the file

Would be grateful, if someone could help me out.

<?xml version="1.0" encoding="UTF-8"?>

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Altair Forum User

Hi,

The center node should be your dependent node and independent should be top nodes when creating RBE3

Why not use RBE2 instead?

Altair Forum User

Hi Prakash

I understand the concept of indenpendent and dependent node. However, how do I select all the independent nodes. Doing it manually makes no sense. It takes too much time. How do I select all the nodes on the upper solid as independent nodes?

Thanks for your help

Sincerely

PS: Sorry I made a mistake in the above screenshot. I wanted to write 'dependent' in the centre. Accidentally wrote 'independent'. Thanks for pointing it out.

Altair Forum User

Hi Prakash

Please let me know as soon as possible

Altair Forum User

Hi,

Selec nodes by face and select any one node on top

Altair Forum User

Hi Prakash

Thanks for the answer. I actually figured out the problem. I had forgotten to delete the 2D mesh and hence when I was trying to select by 'solids', it was just selecting the face.

I just deleted the 2D components and it worked.

Thanks for your help

However, I had another question regarding displacement boundary conditions in Optistruct. In the attached model, you can see that I have created a rigid on both the sides of the part. One side I want to keep completely fix and the other one I want displacement of 20mm. I am not sure how to apply the displacement value to the rigid node which I have created in my model.

Could you please have a look.

Sincerely

Jaivin

<?xml version="1.0" encoding="UTF-8"?>

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Altair Forum User

Hi Prakash

Please reply.

Altair Forum User

@Novak

You can apply enforced displacement using SPCD.

https://forum.altairhyperworks.com/index.php?/topic/22600-displacement-as-load-in-optistruct/&tab=comments#comment-55971

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Altair Forum User

Hi Prakash

So I did the way you told showed me but I am getting an error which says 'Case Control data LOAD=3 is not referenced by any bulk data
relevant for used subcase type.'.

Here is the file. Could you please tell me how to solve it?

Thanks in advance

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Altair Forum User

Hi Novak,

There is no need to refer any load collectors under LOAD when you have defined enforced displacement through SPC cards.

You can combine all the SPC load collectors to one SPCADD card and call this in SPC at load step level.

Thanks

Vikas