topic Re: Confused by bolt connector functionality in Fusion Design, Validate & Document Forum

Confused by bolt connector functionality

greenveg — Tue, 02 Feb 2021 14:18:40 GMT

Bolt connectors seems to "pull through". Is this a bug? Feature? Am I using it wrong?
Kept loads to gravity for simplicity.

Contacts are set to separation with 0.14 static friction coefficient.

All bolts are M6-ish preloaded to 7kN

Re: Confused by bolt connector functionality

TheCADWhisperer — Tue, 02 Feb 2021 14:13:17 GMT

What is the numerical value of the Deformation?

If you set the Deformation Display on Actual - do you get the results that you expect?

Re: Confused by bolt connector functionality

greenveg — Tue, 02 Feb 2021 14:24:12 GMT

I would say calculated real deformation are within expectations.

If I shift to display actual deformation as you sugest and not magnified/adjusted it sure looks better, but I'd expect it to stretch the bolts or something similar, since the bolt connector are specified to a specific surface.

Re: Confused by bolt connector functionality

greenveg — Tue, 02 Feb 2021 15:00:07 GMT

But just so we get this cleared up: is this (bolts in "mid-air") expected behaviour?

Re: Confused by bolt connector functionality

TheCADWhisperer — Tue, 02 Feb 2021 16:13:02 GMT

@greenveg wrote:
But just so we get this cleared up: is this (bolts in "mid-air") expected behaviour?

I was hoping @John_Holtz would comment on this one as he was nearby this morning.

I am pretty sure those are merely graphical glyphs - not meant to be taken as physically modeled components.

If I increase the exaggeration for the load - notice that that glyph stays in original position.

And the exaggeration is merely a graphical representation too.

Re: Confused by bolt connector functionality

greenveg — Tue, 02 Feb 2021 18:47:11 GMT

Yeah I tried adding a zero to gravity as well 😅

Perhaps these are just graphic behaviours/problems that are sending me on false paths.
The bolt-in-threade-hole are also weirdly displayed, there is nothing where they actual thread is. (It is specified to the correct surface and 12mm of thread engagement)

Re: Confused by bolt connector functionality

John_Holtz — Tue, 02 Feb 2021 21:15:46 GMT

Hi @greenveg

I agree with @TheCADWhisperer . The bolts are just a symbol and therefore do not move with the results -- just like none of the other symbols (forces, constraints) move with the model.

The threaded bolts do not make any sense to me. A surface should be selected for the "Location for Threads". It appears to me that sometimes when you edit the bolt, an edge is the selected location, not the surface. Also, the "Usable Thread Length" is the wrong terminology based on the symbol that is creates (and more importantly, based on the FEA elements that are created.) This article is for different software, but it describes how the "Usable Length" is used in Fusion. See Nastran In-CAD: Useful Length of cap screw type bolt connector.

Re: Confused by bolt connector functionality

greenveg — Thu, 04 Feb 2021 13:57:04 GMT

Then I guess this has turned into a feedback/bug report:

Despite doing the exact same thing, bolt connectors on the left side are not displayed with thread engagement. See attached movie clip 🙂
Since the bolt is shown with a color (blue) like it's representing stress/displacement/etc in the result view, the user (me) expects it to behave like the other bodies in the simulation and show displacement/extension in sync with the rest of the colored mesh model. I expect it to stretch.
If it's representation is purely graphical I would not expect to show up colored and looking mesh-ified, I would expect it to show up as solid, or a completely different color (purple for example) as to indicate the blue color is not showing zero stress/displacement. Or possibly just a symbol.

Thank's for caring!

Re: Confused by bolt connector functionality

John_Holtz — Thu, 04 Feb 2021 14:14:40 GMT

Hi @greenveg

This is a bug that the developers are aware of. (All of the threaded bolts should be shown the same way, but they obviously are not shown the same. 😕)
As stated previously, the bolts are just a graphic symbol. It is really no different than the arbitrary blue color used for applied force or green used for applied pressure. Since the color is the same whether the results are shown or not shown, I think most users will not mistake the color as a result. Other clues that the bolt is just a symbol is that the color never changes regardless of what result is shown, the symbol never moves, and there is never a mesh shown for the bolt. (The actual analysis uses a line to represent the bolt, so it would not even look like a bolt if Fusion were to show the mesh.)

Do you have a suggestion for an alternative color? Most colors appear somewhere in the legend. It should not be grey, because most models are grey and it would be hard to distinguish between a real solid part that looks like a bolt and a symbol that looks like a bolt. Maybe that leaves black or dark grey? Perhaps the user should be able to set the color. From a manager point of view: do you have a suggestion that justifies the time required to implement the color change?