how can i model a rigid body?

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thomas
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11 years 3 months ago - 11 years 3 months ago #7377 by thomas

how can i model a rigid body? was created by thomas

Hey everyone,
i have a problem with my fem simulation. i try to build one part of my assembly as a rigid body.
is it right when i use the function

rigid = AFFE_CHAR_CINE(MODELE=model,
                                   MECA_IMPO=_F(GROUP_MA='VR',
                                   DX=0.0,DY=0.0,DZ=0.0,))

to simulate the group 'VR' as a rigidy body or is there any tutorial how i use the functions to give a part the propertiers of a rigid body?

thanks in advanced

thomas

Last edit: 11 years 3 months ago by thomas.

RichardS
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11 years 3 months ago - 11 years 3 months ago #7378 by RichardS

Replied by RichardS on topic Re: how can i model a rigid body?

hello thomas,
what you do is to restrict all DOFs of the group VR, this means it can't move or deform.

If you want a rigid part which is able to displace (translate or rotate) you have to use for example:

fix_relative = AFFE_CHAR_MECA(LIAISON_SOLIDE=_F(GROUP_MA=('VR'),)

but this is only valid in small displacements and small rotations.

For large rotations or large displacements I think the only way is to impose a very high E-modulus.

Best regards,
richard

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Last edit: 11 years 3 months ago by RichardS.

The following user(s) said Thank You: thomas

kwou
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11 years 3 months ago #7381 by kwou

Replied by kwou on topic Re: how can i model a rigid body?

Hoi thomas

it all depends on what you want to achieve, as Richard allready indicated.
You can also replace the rigid body by a mass point with tranlational and rotational inertia.

Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees

The following user(s) said Thank You: thomas

thomas
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11 years 3 months ago - 11 years 3 months ago #7384 by thomas

Replied by thomas on topic Re: how can i model a rigid body?

hey
thanks at first for the answers!

i have a big part which should be a rigid body to get a shorter calculation time.
this part is look like a rectangle frame and at the corners it is in contact with the rest of the model.
at the moment the contact is without friction.
the part should not deform but could displace or rotate.

the idea is to build this part as a rigid body is to get only 6 DOFs.

is this possible with code_aster?

only for my understanding:

AFFE_CHAR_CINE(MECA_IMPO=...),

is for creating a fixed body that can not deform or displace, right?

AFFE_CHAR_MECA(LIAISON_SOLIDE=...),

is for creating a body that can displace but not deform?

kind regards

thomas

Last edit: 11 years 3 months ago by thomas.

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