Splines in ANSYS Workbench

[Diegoaest]

Hi all!

I'm working with ANSYS Workbench v11 and I'd like to know if there's a limitation in the use of splines in DesignModeler. That's because if you change a parameter of a spline (like the position of a point) and then change it again to the initial value, sometimes you don't get the same spline and even sometimes you get strange and useless shapes, but the constraints (tangencies or coincident points) continue satisfying. In order to avoid it is necessary to set values of curvature, does anybody know how to do it?

Changes in splines are used for the process of optimization (DesignXplorer) and some strange shapes give fails. I know the problem is solved by using firstly a CAD software but I'm really interested in doing it all together in ANSYS because then I want to run it in batch mode to use an external optimization method.

Thank you in advance

 

[cbrn]

Hi,
I can see why, mathematically, these "strange" behaviours could occur. But unfortunately I can't really see how to avoid it.
However, with the use of the Parameter Manager, you do have a way to pass parameters back and forth with an external CAD program, provided it is among the ones for which Ansys' Geometry Plugin supports this feature (e.g. Unigraphics NX4).

Regards

 

[Diegoaest]

Yes, I knew that, but I wanted to use only ANSYS. I suppose that is not possible. Anyway, thank you for your attention cbrn.

Regards

 

[cbrn]

Hi,
I understand. You likely need to make the whole thing work even where there isn't any CAD underlying.
But excuse me if I insist, because I do believe it could save you some headaches: even if you have no license for using the CAD interactively on the machine where Workbench is running, in some cases (Unigraphics NX is among them) you still can install it and make it run in batch mode during the geometry interchange. In this case, NO license of the CAD is allocated, since the license is "per use", not "per machine", i.e. if no user "directly" accesses it, it can still run even without being licensed to. However, it depends upon the CAD-vendor's policy.
The problem is that you must have a very robust 3D model, because in case of troubles (incorrect / incongruent parameter, causing a feature to fail...) you won't be able to "debug" anything.

Regards

 

[Diegoaest]

Hi,

I should have explained you before why I wanted to use only ANSYS. Sorry about it. The reason was because working with both programs in the process of optimization would do it very slow since it run the analysis for different geometric parameter combinations (it would open the CAD program in each iteration). In addition, I would have to program in the CAD program language to get the parameter changes. But your response was useful because I started to think that I was wrong. It's possible to run it through the Parameter Manager, passing parameters back and forth as you said, as fast as using only ANSYS (keeping the CAD program opened) and everything in APDL.
The problem is that I haven't experience with APDL and I don't know exactly how the things could be done, but that's another subject...

Thank you very much for your help