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#1 2014-08-20 16:20:54

reiteres
Member
Registered: 2013-06-03
Posts: 558

[Solved]Replace liquid py point mass

Hi!

Is it possible to replace a liquid in solid form by a point mass?
This could be useful for comparisons.

I think I saw there exists some command. If yes could some direct me to a test case?
If no has someone an example with a simple point mass? I quite don't konow how to join a point mass with the rest of the sytem?
Add a LIAISON_SOLDE to the contact faces?

Last edited by reiteres (2014-11-17 20:14:14)

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#2 2014-08-29 16:26:51

pafortin
Member
Registered: 2014-05-06
Posts: 23

Re: [Solved]Replace liquid py point mass

Hi Reiteres,

I use point masses to replace liquid masses by connecting the point mass to the structure with RBE3 links. This methogology is used in my company to model liquid masses in merchant ships such as tankers or LNG carriers although so far we used Nastran. I am trying to do the same with Code_Aster with the LIAISON_RBE3 operator.
It is quite a simplification because it is tricky to position the mass so that the efforts transmitted by the RBE3s correctly represent the pressure due to the liquid but it seems to work more or less.

Best,

Pierre-Arthur

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#3 2014-11-06 14:27:48

reiteres
Member
Registered: 2013-06-03
Posts: 558

Re: [Solved]Replace liquid py point mass

Thank you for your answer, and sorry for my late response. I was not really active in the forum for a while and oversaw that.

Using RBE3 sounds reasonable, but are there examples to learn from or does one have to adjust the linking parameters by trial and error?

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#4 2014-11-17 20:13:48

reiteres
Member
Registered: 2013-06-03
Posts: 558

Re: [Solved]Replace liquid py point mass

Ok I tinkered around a little bit and the result seems reasonable (although it does not find all modes as in the case with 3D_FLUIDE; but I don't know how much I can trust 3D_FLUIDE anyway ...)

Enclosed example for reference

Last edited by reiteres (2014-11-17 20:40:07)


Attachments:
RBE3_example.tar.gz, Size: 97.96 KiB, Downloads: 145

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#5 2014-11-23 16:23:33

keeswouters
Member
From: kuringen
Registered: 2007-12-01
Posts: 144
Website

Re: [Solved]Replace liquid py point mass

Hoi Reiteres

I used RBE3 to apply a moment to a cylinder once.
I used a massless node connected to the axial face of the cylinder by RBE3.
I still not convinced that RBE3 works well under ''all'' circumstances in C-Aster.

see:
http://www.caelinux.org/wiki/index.php/ … rs/bc/rbe3

Last edited by keeswouters (2014-11-23 16:24:37)


kind regards - kees
--
I a parallel univers the laws of mechanics may be different.

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#6 2014-11-23 20:00:15

reiteres
Member
Registered: 2013-06-03
Posts: 558

Re: [Solved]Replace liquid py point mass

Hi!

I don't think that RBE3 connections are far from perfect, but If you deal with very big models and short on time it's
better than nothing, since it appears to me that the results are not completely out of the world.

But you are right when you speak out a warning. They have the be handled with care!

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