[Gmsh] Importing Nastran BDF

Christophe Geuzaine cgeuzaine at ulg.ac.be
Sat Apr 19 11:01:11 CEST 2008

Todd Martin wrote:
> Hi Chris
> The more I use gmsh, the more I like it.
> I have two questions.
> a) when importing a BDF file, gmesh currently creates "elementary 
> entities" for each element according to its Nastran property id. 
> Shouldn't these be "physical groups" instead? These physical groups 
> could then be used to assign properties in Code-Aster.
> (it would be even better if load and constraint points were 
> automatically converted to physical groups as well.)
> b) Since "physical groups" can be named in gmesh, can these names be 
> used in Code-Aster to identify mesh groups, instead of "GM100" etc. 
> Perhaps this is a question for the Code-Aster people, but I thought you 
> might know.

Hi Todd - With version 2.2 you can directly export meshes in Aster's MED

// load your Nastran file
Merge "mesh.bdf";

// define some physical groups
Physical Surface("my surface") = 6;
Physical Line("left boundary") = 4;

then save as "mesh.med".

Then Aster should be able to use the strings directly.

> I am very familiar with the Nastran solver, so I'd be happy to supply 
> any details about the bulk data format. In fact, soon I will be 
> comparing the results of some simply loaded composite plates in 
> Code-Aster and Calculix with those of NE Nastran. I'm pretty sure the 
> Calculix post-processor can export gmesh files, so I just need to get 
> the Nastran results out of FEMAP to view all the results in gmesh.
> I'm using gmesh version 2.1.0-nightly-20071025
> Thanks,
> Todd.
> Ph.D. Mechanical Engineering, B.E. (1st Class Honours)
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Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science