Competition: kinematic simulation of a coupling gear

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thomas-neemann
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Competition: kinematic simulation of a coupling gear

Post by thomas-neemann »

in the 90s i had a request for such a task,
Bildschirmfoto_2022-05-20_13-40-56.png
Bildschirmfoto_2022-05-20_13-40-56.png (260.7 KiB) Viewed 2086 times

Bildschirmfoto_2022-05-20_13-41-36.png
Bildschirmfoto_2022-05-20_13-41-36.png (197.71 KiB) Viewed 2086 times

example
Bildschirmfoto_2022-05-20_13-46-17.png
Bildschirmfoto_2022-05-20_13-46-17.png (59.84 KiB) Viewed 2086 times

without electronic control, purely mechanical. at that time it was solved with special software. I think freecad can do that too. who wants a competition?


the task is that the work basket is always (in every position) as vertical as possible
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Re: Competition: kinematic simulation of a coupling gear

Post by NewJoker »

It's hard to find open-source software for kinematic analysis and there's pretty much no FOSS program capable of analyzing simple 2D mechanisms but some solutions for multibody dynamics analyses exist and can be integrated with FreeCAD: https://www.youtube.com/user/josegegas/videos
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Re: Competition: kinematic simulation of a coupling gear

Post by thomas-neemann »

NewJoker wrote: Fri May 20, 2022 12:11 pm ..
I think it should be possible in this way

https://www.youtube.com/watch?v=XaGRVKvpq8U

phpBB [video]
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Re: Competition: kinematic simulation of a coupling gear

Post by NewJoker »

thomas-neemann wrote: Fri May 20, 2022 12:49 pm I think it should be possible in this way
Yes, the sketcher with its constraints, DOF handling and mouse dragging can be very useful for simple geometric analysis of a mechanism but won't provide you the data needed in most cases - positions, velocities and accelerations (not to even mention forces and moments) of points and links belonging to the mechanism throughout its whole range of motion under applied velocity, for example.

That's possible with proper sketches in commercial software: https://www.youtube.com/watch?v=pBczBrM7uq0

It would be awesome to have a module for that in FreeCAD and there were a few discussions about that in the past but a proper solver would be needed. For now, the only option is full 3D MBD software which is overkill in most cases of simple mechanisms.
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Re: Competition: kinematic simulation of a coupling gear

Post by thomas-neemann »

NewJoker wrote: Fri May 20, 2022 2:05 pm ..
at that time it was mainly about the geometric solution, but the forces could also be determined with the software. via a geometric method
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Re: Competition: kinematic simulation of a coupling gear

Post by thomas-neemann »

here is a first suggestion
1734-teil2.FCStd
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https://www.youtube.com/watch?v=CfshdfDwos4

phpBB [video]
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Re: Competition: kinematic simulation of a coupling gear

Post by thomas-neemann »

NewJoker wrote: Fri May 20, 2022 2:05 pm ... moments..
here is a suggestion for the moments

https://www.youtube.com/watch?v=xT3C_zuN8I4

phpBB [video]
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Re: Competition: kinematic simulation of a coupling gear

Post by toni_lv »

If you want to do pure 2D mechanism analysis I recommend this piece of software (https://github.com/KmolYuan/Pyslvs-UI). It is a bit hard to model linear joints but it works great and very quickly. Maybe in a future Sketcher gets better and has more functionalities, but right know I would use this tool.
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Re: Competition: kinematic simulation of a coupling gear

Post by thomas-neemann »

toni_lv wrote: Fri May 20, 2022 10:42 pm ...
Thanks for the tip, I found a video about it

https://www.youtube.com/watch?v=L55kriGU4HU

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Re: Competition: kinematic simulation of a coupling gear

Post by NewJoker »

thomas-neemann wrote: Fri May 20, 2022 6:06 pm here is a suggestion for the moments
Right, Sketcher's capabilities allow for quite advanced geometric analyses of mechanisms. And it's interesting that you can calculate the forces and moments, at least for simple cases.

toni_lv wrote: Fri May 20, 2022 10:42 pm If you want to do pure 2D mechanism analysis I recommend this piece of software (https://github.com/KmolYuan/Pyslvs-UI).
I've seen this one some time ago when I was searching GitHub for mechanism analysis software. Unfortunately, it seems that it can't calculate velocities, accelerations and other outputs, just like all the remaining FOSS codes.

This one is also interesting but again, it can't calculate anything and just animates mechanisms: https://blog.rectorsquid.com/linkage-me ... simulator/
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