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Importing a mesh

Phenom
Phenom
NX5

We just had a demo of a 3D scanner, and during the demo they mentioned that the scan data was a "mesh", and that we should be able to import it, and do FEA.

The output we were given was a .stl , but when I import it, I get a typical STL file, not something that looks like a "mesh".

Is there a special way to import this into Advanced Simulation? or is this just not going to work, as the rep. thought?

Thanks,
Dave
-Dave
NX 11 | Teamcenter 11 | Windows 8.1
3 REPLIES

Re: Importing a mesh as STL

Innovator
Innovator
Dear Dave,
Based in my experience I will tell you the status with STL files with NX7.5, then you can make an idea regarding NX5:
• Importing STL files is posible only if you are in the part environment, then you will see STL option under "File > Import > STL".
• NX 75 will try to create a solid body.
• If you are user of NX Advanced Simulation and you try to use "File > Import > Simulation" then you will note that STL option is missing.

In summary, you can import the analysis results to NX as STL data to create faceted bodies, that later you can mesh with NX AdvSim, but not directly like 2-D FEA mesh.

But please note that if you were user of FEMAP (software product of the SIEMENS portfolio of simulation FEM/FEA programs) you can import STL files in FEMAP as 2-D mesh:

FEMAP can also read files that were generated for StereoLithography production (STL). These files are usually text files, but can be binary as well. FEMAP can read all text versions, and binary files if they were generated on a PC. The facets in the StereoLithography file are converted to triangular surface elements during the translation.
When you select the File, Import, Geometry command and select a Stereolithography file, you will see the Read Stereo Lithography dialog box. In addition to just translating the triangular facets, however, FEMAP can automatically merge all coincident points and split any facets that are necessary to eliminate free edges in the mesh. The options on this dialog box control merging, definition of short edges, as well as closing of gaps. This results in a valid finite element mesh, although typically with very bad aspect ratio elements. The facets can be remeshed with the Mesh, Remesh commands.

Use the PASTRAN STL File option to read PATRAN STL files. This option will also let you read any STL file where the negative coordinate locations are written without spaces between the X,Y, and Z components.

FEMAP can also write Stereolithography files as well. FEMAP will ask you to select the elements to be translated. You will usually want to pick plane element types for this command. If you have quadrilateral plane elements, FEMAP will still write the triangular facets by first splitting these quads. This splitting procedure does not modify the elements themselves. FEMAP simply writes the triangular results to the STL file. If you choose solid elements, FEMAP will write each face as a triangular facet, splitting quadrilateral faces when required. Any line elements that are chosen in this procedure are simply ignored.

Atached I send you a few pictures of the process.
Best regards,
Blas.

Re: Importing a mesh

Phenom
Phenom
Thanks, I'll have to see if we have FEMAP!
-Dave
NX 11 | Teamcenter 11 | Windows 8.1

Re: Importing a mesh

Siemens Phenom Siemens Phenom
Siemens Phenom
Dave,

NX 7.5.2 Advanced Simulation supports import of STL data as a linear triangle mesh. Here are instructions for you to use when you get NX 7.5.2:

1. Create a PRT
2. Import STL using the NX facetted body option
3. Set the following environment variable: UGII_CAE_JT_SUPPORT = 1
4. Restart NX
5. Create a new FEM from the PRT

The environment variable above will cause NX to create shell elements from the facetted body triangles that originated from the STL.

New in NX 7.5.2 is the ability to create polygon faces from shell elements and solid element faces. Once a polygon face exists, it can be meshed. So, with STL you can create polygon faces of unstructured data and generate a mesh suitable for analysis. Let me know if you want to investigate this solution further. If you are a member of the PLM World NX Simulation SIG (Special Interest Group), you can download a workshop on polygon face from mesh techniques. It doesn't include steps 1-3 above for STL support, but that's the easy part.

http://www.plmworld.org/p/co/ly/gid=36

Regards,
Mark