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#1 2008-08-04 15:07:17
Component Mode Synthesis data generation for MBDyn
Hi all. As anticipated in related postings http://www.code-aster.org/forum2/viewtopic.php?id=12486 , http://www.code-aster.org/forum2/viewtopic.php?id=12503 , I'm trying to generate Component Mode Synthesis data for MBDyn http://www.aero.polimi.it/~mbdyn/ using Code Aster. The data consists in:
- (exposed) FEM nodes (labels)
- (exposed) FEM node locations (grid point positions)
- (exposed) FEM node mode shapes (from modal and Craig-Bampton analysis)
- generalized mass matrix
- generalized stiffness matrix
- optionally, either diagonal of mass matrix (at exposed nodes) or rigid-body inertia
So far, I succeeded in generating most of the data (except for the last item) for most of the application cases need by MBDyn (what's missing right now is:
- cases including rigid-body modes,
- the purely static element,
- cases with scalar degrees of freedom,
- cases with non-trivial imposed nodal motions).
A description of the syntax for the modal element data is available here:
http://www.aero.polimi.it/~masarati/MBD … ode65.html
An example of the macro I prepared so far is attached to this message, along with a few example files that run it. You'll need to modify the files to look into the right paths (grep for '/home/masarati' 
. Run "./cms.sh <id>", where <id> is either 0, 1 or 2 to run different test cases.
A related question is: what's the preferred way to augment Aster with custom macros? I mean: is there a mechanism, or a preferred location where macro .py files should be stored? Right now, I'm doing something like
path_to_cms_macro = "/path/to";
import sys
sys.path.append(path_to_cms_macro);
from cms import CMS
but there might be better approaches. I'm planning to distribute the macro along with examples with the next release of MBDyn, and I'd like to be able to suggest the most appropriate location for the files I provide.
Cheers, p.
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#2 2008-08-05 15:48:44
Re: Component Mode Synthesis data generation for MBDyn
I've managed to solve the mass matrix manipulation issues; now both the diagonal of the mass matrix and the rigid-body inertia matrix can be extracted, by requesting them with the appropriate options. See the attached file.
BTW, the possibility to manipulate the mass matrix will allow me to solve the next (unrelated) problem: how to compute a vector of inertial loads resulting from a given accelerations field. Stay tuned...
Cheers, p.
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#3 2008-08-05 20:57:01
- bosman
- Member
- Registered: 2008-07-14
- Posts: 34
Re: Component Mode Synthesis data generation for MBDyn
Hi!
Very good work!! Thanks!
Bernt-Ola
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#4 2008-08-05 21:23:45
Re: Component Mode Synthesis data generation for MBDyn
Thanks. If you make use of MBDyn with modal data generated by Code Aster, please feedback. The CMS() macro can be improved in many ways (see e.g. the TODO comment for a very preliminary list I have in mind right now, but there might be more, based on users' needs). Also, my experience in python programming and in using Aster is less than ten days long, so there might be room for lots of optimization. Also, if you've a project that makes use of MBDyn and you want to share it with others, please send me a link and I'll put it into the research page.
Cheers, p.
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#5 2009-02-06 15:15:02
- zhaoguang
- Member
- Registered: 2009-01-14
- Posts: 170
Re: Component Mode Synthesis data generation for MBDyn
ando wrote:
Thanks. If you make use of MBDyn with modal data generated by Code Aster, please feedback. The CMS() macro can be improved in many ways (see e.g. the TODO comment for a very preliminary list I have in mind right now, but there might be more, based on users' needs). Also, my experience in python programming and in using Aster is less than ten days long, so there might be room for lots of optimization. Also, if you've a project that makes use of MBDyn and you want to share it with others, please send me a link and I'll put it into the research page.
Cheers, p.
===========================
Hello ando,
Thank you for your postings.
I am interested in using modal data generated by Code_Aster for simulation (e.g: modal synthesis to generating sound, etc).
My experience in using Code_Aster is about 15 days.
---and I have got mass matrix and rigid matrix, but the manipulation is not so easy, because it's such a big matrix. see file attached, and could you give some advice?
---But I know nothing about MBDyn. It is based on UNIX OS, right?
looking forward to your reply.
Regards
---------
zhaoguang
Last edited by zhaoguang (2009-02-06 16:50:34)
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#6 2009-02-07 15:45:55
Re: Component Mode Synthesis data generation for MBDyn
I am interested in using modal data generated by Code_Aster for simulation (e.g: modal synthesis to generating sound, etc).
My experience in using Code_Aster is about 15 days.
---and I have got mass matrix and rigid matrix, but the manipulation is not so easy, because it's such a big matrix. see file attached, and could you give some advice?
---But I know nothing about MBDyn. It is based on UNIX OS, right?
---------
zhaoguang
Hi. I'm not sure what you're asking my help about. If it is about Code Aster, then I might not be the right person, as I have only a very limited knowledge of the software. If it is about the macros I wrote, then please be more specific. If it is about MBDyn, then this might not be the right forum; please subscribe to mbdyn-users@mbdyn.org and post your questions there. You might first want to browse the web site http://www.aero.polimi.it/mbdyn to familiarize with the software.
Cheers, p.
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#7 2009-07-21 05:39:43
- bradcapo1
- Member
- Registered: 2009-07-21
- Posts: 1
Re: Component Mode Synthesis data generation for MBDyn
Thanks for sharing this useful information. It's great.
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#8 2009-07-31 05:07:46
- Karato
- Member
- Registered: 2009-07-31
- Posts: 1
Re: Component Mode Synthesis data generation for MBDyn
I would not accept as an alternative to: 'Do you own a car?'
sonnerie portable mp3 - Sonnerie portable MP3 est en effet unpouvoir de l'innovation technologique. Ętes-vous familier avec cette sonnerie portable?
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