topic Re: Frame Generator -> Dynamic Simulation -> FEA: Is it possible? in Inventor Forum

Frame Generator -> Dynamic Simulation -> FEA: Is it possible?

dgeise — Mon, 29 Jul 2019 01:27:10 GMT

Hello, I'm trying to use Inventor Frame Generator to generate two frames, constrain the two frames together leaving one degree of freedom between them (axis rotation), use Dynamic Simulation to calculate forces imparted on the frames in various scenarios, then export those forces into FEA for analysis / validation. It think this all sounds reasonable, right? But I can't seem to get it to work no matter what I do. The simulation runs without problem, but the issue is that the export to FEA step rejects selection of the frame subassembly, saying it needs to be set to Flexible to be exported. However the generated frame assemblies and their containing assembly are set to Flexible and everything I try results in the same error message. I was able to throw together a few parts into a flexible assembly and get simulation -> FEA to work, but it only works for a single part in isolation. This is somewhat useful, but I really need to see the FEA results at the frame assembly level, not just individual parts. The solution seemed to be to derive the two generated frame assemblies into two parts, constrain them together in the same way, simulate, and export the frames (now as parts) to FEA. However, for some reason this results in the same - even though the assembly is set to flexible and only contains parts (not assemblies), the export to FEA step generates the same error that the assembly needs to be flexible even though I'm selecting (derived) parts. This happens no matter how I derive a frame to a part - single-body, multi-body, etc. Am I doing something wrong here? Can someone (Autodesk?) please post an outline of the steps to take to do FEA analysis of frames where the loads are generated by dynamic simulation?

Re: Frame Generator -> Dynamic Simulation -> FEA: Is it possible?

Xun.Zhang — Mon, 29 Jul 2019 02:52:54 GMT

Hello @dgeise,

Check out below demo video for reference and hope it helps!

Re: Frame Generator -> Dynamic Simulation -> FEA: Is it possible?

JDMather — Mon, 29 Jul 2019 06:17:11 GMT

@Xun.Zhang

I just skimmed through this so I might have missed it, but at what timestep did this video make use of Dynamic Simulation (motion loads)?

@dgeise

Attach your Derived Component example.

Re: Frame Generator -> Dynamic Simulation -> FEA: Is it possible?

dgeise — Tue, 30 Jul 2019 06:35:57 GMT

@JDMatherThanks so much for responding. I hope to file a patent so there are potential disclosure issues preventing my sharing the raw files. Furthermore, I should have mentioned this - the version of Inventor I'm using is quite old (2014) and I don't know if the files are even compatible with newer versions. So I think tomorrow night I'm going to try temporarily installing a recent version on a 30-day evaluation license and try to reproduce a simplified scenario there. Perhaps the issue's been fixed in newer versions or the simplified version might help clarify things. If I'm still stuck I'll share that in a few days. Thanks for offering to help! And you're right, nothing on motion loads in that video.

@Xun.ZhangThanks for the link - although this is an interesting video and I did learn a new trick, it doesn't really relate my problem. It's only about Frame Generator -> Frame Analysis, not this Frame Generator -> Dynamic Simulation -> FEA issue.

I'm quite surprised - this use case seems like it would be common but apparently isn't - I've searched extensively and can't find anything remotely relevant to this specific problem on this forum or elsewhere. I even purchased and read "Up and Running, Vol 2" and didn't find anything that might help nor did the author respond when I tried to email him.

@Xun.Zhang, while I have your attention, you know what would be a great "get it done" project for the @Inventor developers? [Besides getting this feature properly working or at least documenting it so users can get it to work] The ability to export Dynamic Simulation forces into Frame Analysis, which is so much faster than FEA. That would be great for doing fast, iterative early virtual prototyping. Not being bogged down by the full FEA path where results are measured in hours not seconds would make the process much more fluid and intuitive. I really miss ForceEffect and regret allowing iOS to update and break the app - it makes using Inventor seem so complex, slow and incredibly picky in comparison... I hope Autodesk gets back to something like that (but in 3D of course) some day. Ease of use & rapid feedback are very saleable features.

So... I guess as a last resort I could manually copy the Dynamic Simulation results into FEA and/or Frame Analysis. Is that how people are working around the problem? Or am I just being a naive user here?

Re: Frame Generator -> Dynamic Simulation -> FEA: Is it possible?

dgeise — Thu, 01 Aug 2019 20:44:08 GMT

Probably the final update on this thread, mostly for the benefit of others who might stumble on this while having similar issues -

Last night I went ahead and tried to reproduce the issue on Inventor 2020 (via cloud) and... It actually worked.

So apparently it's an issue with v2014 that was resolved in a later version. I've decided to just evaluate the motion loads from Dynamic Simulation and hand-enter loads into FEA since that seems like the shortest & least expensive path for me.

Re: Frame Generator -> Dynamic Simulation -> FEA: Is it possible?

Frederick_Law — Thu, 01 Aug 2019 20:54:28 GMT

Make sure you save a copy of the old file.

Once you save in 2020, you can't open them again in 2014.