Import geometry from a CAD program 1

[KuJayHawk]

We are trying to import the geometry of a steel bridge from MicroStation file into ANSYS. MicroStation is a CAD program like AutoCAD. It can export files in formats such as IGES, SAT, CGM ... The file format we selected is SAT. When imported into ANSYS, we got lines curved and areas not shown up in colors (only in numbers). Or, if we allow defeaturing, the imported file shows areas properly but the lines are not connected as originally set up in the CAD file. Does anyone have similar experience dealing with this type of problem before?

Thanks ahead for any help and input to my question!

 

[cbrn]

Hi,
the preferred file formats for import into ANSYS are IGES and Parasolids.
It is very likely that ANSYS will give you some topological problems if the areas / lines are not properly sew up in the CAD's export-translator. In that case, if you use Ansys Classical you will have to make some kind of repair, or play with import tolerance. Also consider that Ansys Workbench is far more tolerant and clever as regards import from CAD files, so I'd suggest to use it if you can.

Regards

 

[KuJayHawk]

Thanks so much , cbrn! I never used Workbench before but I do have it loaded on my computer. I actually scheduled a Workbench demo at our office later this week. Hopefully those guys from ANSYS can give us a jump start on this new product. Also, MicroStation can export to IGES files too. We will look into this and give it a try.

 

[meshparts]

In the model, that I'm just working on, I import SAT from Solid Works into Ansys. It works just fine, but with one small graphical problem: the geometry (area and volumes) is displyed as wire frame.

It should be possible to change it, but I don't know how...

Dose anybody??

 

[doatis]

Usually, with "dirty" CAD files, ANSYS will turn the set itself to display in wireframe. To change back, use the following command:

/facet,norm

This will tesselate the areas and display as solids.

I've had better luck with .step files from "difficult" CAD packages. If you want to use .iges, you can try the following trick:

1 - Export from Microstation as an .iges
2 - Read the .iges into Microstation
3 - Export this new file as an .iges

Sometimes this will work because the CAD program will have to run it's own smoothing/repair routine over the geometry. This may fix some problems.

However, if you still have problems, you'll probably have to do a bit of geometry repair. You can import the geometry so that you have lines overlapping and then use the nummrg command to try and collapse coincident keypoints/lines.

As cbrn says, Workbench usually handles difficult geometry much better.

Good luck

 

[meshparts]

Thank you, doatis!