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## #1 2020-02-21 16:29:00

vortexe313
Member
Registered: 2020-02-13
Posts: 16

Hello everyone.
I'm trying to apply a force in the radial direction on a cylinder. I don't know exactly how to define the radial direction in code_aster or how to define a force that is node dependent.
Can you help me?
Thank you.

Last edited by vortexe313 (2020-02-21 16:29:17)

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## #2 2020-02-22 15:37:54

mf
Member
Registered: 2019-06-18
Posts: 63

Hello,

a negative PRES_REP on it's curved surface would act like a radial force pointing outwards. It's radius will increase and depending on your NU it will get shorter. Is that what you want?

Bye,

Mario.

Last edited by mf (2020-02-22 15:40:11)

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## #3 2020-02-24 00:23:54

vortexe313
Member
Registered: 2020-02-13
Posts: 16

Hi,
I tried to apply PRES_REP, it works, thank. Is there some option for applying it on curve and not on a surface?
Also, do you know some way to define a force acting on nodes, which is dependent on the coordinates of the nodes?
Thank you

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## #4 2020-02-24 17:35:01

mf
Member
Registered: 2019-06-18
Posts: 63

Hello,

PRES_REP can't do that, I'm pretty sure. But what if your surface is really slender, like a very thin ring (partition the model)?

I'm sure the rest is possible in Aster in a few different ways, although I'm maybe not good enough for that. I can imagine doing it with a LIAISON_DDL, but I have to figure that out (somehow put the definition of a circle in 3D in there and add a little dr to the radius..force has to be calibrated then, though.). I'm really not sure....

Maybe a real Aster-pro can give it a try?

Mario.

Edit: LIAISON_DDL can only do linear relations...so this does not seem possible because of the quadratic terms....

Last edited by mf (2020-02-24 17:46:02)

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## #5 2020-02-24 20:09:17

mf
Member
Registered: 2019-06-18
Posts: 63

Hi again,

I had a look around in the forum, and unfortunately cylindrical coordinates do not seem possible in Aster. Albeit, this here seems to be  somewhat of an exception, but not exactly:
According to post id=18200 applying a radial displacement is possible, although only to a surface. There is the not very elegant workaround if you want to put an IMPO to an edge, or in this case, a slender ring resembling an edge. I'm not sure if this is what you want, but have a look at LOAD 3 in the attached example: I partitioned the top circular face and applied a FACE_IMPO with a DNOR to the outer ring (I excluded the inner part of the circular top surface). It is NOT PRETTY but maybe it helps. So somehow it is the displacement version of applying a PRES_REP to a slender ring (equally ugly 'solution').

Ciao,

Mario.

Last edited by mf (2020-02-24 20:17:07)

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## #6 2020-02-29 11:53:51

konyaro
Member
From: Genève
Registered: 2016-04-02
Posts: 248

Hello,
you can use AFFE_CHAR_MECA_F, cf. attached example.

Konyaro

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