Supports in Inspire: Rotational constraint

Altair Forum User

In 'Apply supports', only displacements (Ux, Uy, Uz) can be constrained, as shown in the below image.

But how to apply rotational constraints (Rx, Ry, Rz)??

 

 

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Mario_21478

Hello,

since you have attached the constrainst to a solid, you have only translation DOFs.

Solids are generally meshed with Tetras, these elements havn't rotatory DOFs.

 

You can check it by attaching a constraint to a surface, now you can see them...

 

Best Regards,

Mario

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Altair Forum User

Can I use surfaces as non-design space parts??

Mario_21478

I don't use surfaces inside Inspire,

If you want to supress rotations at the edge, then cut small stripes and use normal constraints.

 

Best Regards,

Mario

 

 

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Altair Forum User

Could you please elaborate on how to cut small stripes??

Mario_21478

Hello again,

 

Try the following:

• select the line tool
• pick the face of interest
• draw 'cut' line on this face
• exit line tool

Best Regards,

Mario

 

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

Altair Forum User

Altair Forum User said:

• draw 'cut' line on this face

I'm afraid, I'm having trouble in this step. How do I do this?

And, what is a normal constraints?

Mario_21478

It's very simple, you draw a simple line on the existent part. If you finishing the tool, this surface is splitted...

Normal constrain is the standard constrain for solids, as you have shown in the first post. Since all nodes on the surface are constrained in translation, the rotations are also not possible (force pairs).

 

 

Altair Forum User

I have tried it but still unable to see the rotational arrows. Does it mean rotational constraints are free or fixed??

 

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Mario_21478

Hello,

 

since you have now constrained translation dofs on more then one row of nodes (all nodes on the small surface), the rotations are fixed by this translations.

But try it, you will see ;-)

 

Best Regards,

Mario

 

Altair Forum User

Hi Mario,

1. What if I assign the supports in the following way? I do not need to cut small strips, instead I have just assigned them to the face directly.

2. Another question, the supports are free to translate in Y, the rotation is free too or fixed?

 

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Mario_21478

Hello,

1. You can constrain a full surface of course. You need the stripes only if you want to have local constraints.

2. You model have rigid body modes and is so far singular (since translation in Y are free). Rotations about Y are constrained, Rotations about X and Z are free at the moment.

 

Best Regards,

Mario

 

Altair Forum User

Hi Mario,

I there any way I can define the plate as rigid body?? I actually do not want any rotations.

 

Desired Boundary Conditions for the whole plate (not just the faces) -

[Ux = Uz = 0, Uy = free]

[Rx = Ry = Rz = 0]