Re: Inventor FEA results not matching - Page 2

Anonymous · ‎06-12-2015

So I am having problems with getting my stress analysis results to match together. I get that the same simulations (even if they are copied) may yield different stress results from mesh and convergence and all that.

My problem is that when I run a simulation in a part (.ipt) file a few times and average the fairly close results, and then place that part inside an assembly (.iam) by itself and run the same setup, I get a pretty different result. My part is a pretty simple rod fixed constrained at one and and a force on the other. The values for stress in the part file are ranging from 103-122 ksi, and the stress of the part in an assembly by itself are around 71-76 ksi.

If anybody has any idea why this is happening, some insight would me much appreciated.

Thanks.

Anonymous · ‎06-16-2015

One thing to note is that assemblies and parts carry out their mesh refinements in different ways in Inventor, regarding the "p" and "h" refinements.

JDMather · ‎06-16-2015

@Anonymous wrote:
IAM with only one part?

Yes. I was thinking of adding a second instance as the "wall" connection part. Fully Fix the faces of the "wall" and Bonded Contact and see what results I get, but haven't had time.

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Anonymous · ‎06-16-2015

@Anonymous wrote:
Thanks, I IAM with only one part?

Yes. As the OP mentioned, he/she was simply trying to determine why the models mesh differently when a single .ipt, vs that same .ipt in an assembly.

blair · ‎06-16-2015

Odd, Displacement is identical, yet different Stess. Looks like an issue in FEA. I thought there was an issue back in IV2014 that was simular to this and a patch fixed it. Looks like the same issue is back in IV2016.

I'll forward this on to ADSK.

Inventor 2020, In-Cad, Simulation Mechanical

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blair · ‎06-16-2015

Works fine in Simulation Mechanical. I get the same results as a IPT file or IAM file.

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Anonymous · ‎06-16-2015

@Anonymous wrote:
Works fine in Simulation Mechanical. I get the same results as a IPT file or IAM file.

Nice find.

That's a little unsettling though...

blair · ‎06-16-2015

I thought the same thing happened back on IV2014 and a patch came out fairly quickly. Looks like someone grabbed the same code for IV2016 release.

Since Stress is a secondary value as a result of Displacement. If the Material is the same and the Displacement is the same, then the Stress must be the same.

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Anonymous · ‎06-16-2015

I'm able to get the same result in the part vs the assembly by using local mesh control on all faces in the part and the assembly, obviously using a common element size, such as 3".

You need to pay attention to the convergence rate though, as assemblies and parts have different mesh refinement processes.

Inventor FEA results not matching

Inventor FEA results not matching

Inventor FEA results not matching

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