Inventing wheels.. with built-in suspension =p

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DeepSOIC
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Re: Inventing wheels.. with built-in suspension =p

Post by DeepSOIC »

A_3 wrote:still working on the project?
Not exactly. I've made a few derivatives, as a grinding/sharpening wheels. They are great, with the only problem that sandpaper wears off quite quickly.

The design is quite really similar :P
WP_20170424_22_53_02_Pro_.jpg
WP_20170424_22_53_02_Pro_.jpg (645.43 KiB) Viewed 3478 times
Two left ones are identical, one has a motor spindle inserted into it (stator removed). There, spokes serve an additional purpose of creating intense airflow through the motor (they work like a centrifugal blower, and they have openings for the air through the hub).

I also am considering making an RC-car wheel based on this project, but I need to find someone who is into the topic. I'm not an RC person myself... yet!
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Re: Inventing wheels.. with built-in suspension =p

Post by A_3 »

Nice job, new application of wheel :D
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DeepSOIC
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Re: Inventing wheels.. with built-in suspension =p

Post by DeepSOIC »

A project I randomly noticed in hackaday spammy emails. I'm not related to the project. Wheel design is similar, with a very interesting twist in tire design.
https://hackaday.io/project/26208-fpv-rover-grover
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saso
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Re: Inventing wheels.. with built-in suspension =p

Post by saso »

Some time ago I was working on something (don't really remember anymore what it was :roll:), but it made me remember your wheels and have the idea, "what if you would fill the empty space between the wheel printed structure with silicone (silicone rubber can be made from very soft to quite hard), or something similar, to make the wheel structure stronger but keep it flexible"... Well, when I saw your update I realized that I have also forgot to mention this here in the forum :)
thschrader
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Re: Inventing wheels.. with built-in suspension =p

Post by thschrader »

tom wrote: Wed Aug 31, 2016 12:02 am That is a very cool project! How about using the FEM workbench in order to find the most stressed points?
Here we go! Yes, cool project :)
Loading is 100 N (=10 kg, red arrows, green arrows is fixing)
max v.mises stress = 320 MPa
That means: you need steel ;)
wheel.JPG
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paul18
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Re: Inventing wheels.. with built-in suspension =p

Post by paul18 »

@thschrader :

I think the boundary conditions you've implemented lead to a stress overestimation; the maximum stresses are probably localizzed on the elements immediatly near the clamped ones!

If I were you, I would have :
- implemented contact conditions between the wheel and the ground
- as well as between the spokes and the outside diameter
- had a look if it's possible to model only a part of the wheel

If possible :
- the mesh must be refined (with brick elements) near the maximum stress localization, and coarser elsewhere (but not mandatory of course)
- the use of rigid elements to apply the loading on a basic node, on the centre of the wheel, will help

What type of material features have been used:
- isotropic material? Young modulus, Poisson ratio and density?
- they correspond to what type of infill?

The conclusion may not be different from yours (the part does not whistand the loading), but the values/accuracy of the finite element analysis strongly depend on how it has been modelled!

Paul
thschrader
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Re: Inventing wheels.. with built-in suspension =p

Post by thschrader »

paul18 wrote: Wed Aug 30, 2017 8:55 am @thschrader :

I think the boundary conditions you've implemented lead to a stress overestimation; the maximum stresses are probably localizzed on the elements immediatly near the clamped ones!

If I were you, I would have :
- implemented contact conditions between the wheel and the ground
- as well as between the spokes and the outside diameter
- had a look if it's possible to model only a part of the wheel

If possible :
- the mesh must be refined (with brick elements) near the maximum stress localization, and coarser elsewhere (but not mandatory of course)
- the use of rigid elements to apply the loading on a basic node, on the centre of the wheel, will help

What type of material features have been used:
- isotropic material? Young modulus, Poisson ratio and density?
- they correspond to what type of infill?

The conclusion may not be different from yours (the part does not whistand the loading), but the values/accuracy of the finite element analysis strongly depend on how it has been modelled!

Paul
Paul, thanks for the advice. You are right, this can be done better. It was only a first approach.
I have no good experience with contact-problems (christoph/UR_ ,you are welcome :) )
The use of brick elements is not supported by gmsh/netgen in freecad (have I missed something?)
Material is default-pla from FEM-WB, see file (file with cleared mesh)
regards Thomas
swheel v02 cleared.FCStd
(315.66 KiB) Downloaded 79 times
Job done with:
OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.11935 (Git)
Build type: Release
Branch: master
Hash: a5bc70cca0d2eaa56709603521650ccb3d8d926c
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: German/Germany (de_DE)


swheel v02 cleared.FCStd
(315.66 KiB) Downloaded 79 times
paul18
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Re: Inventing wheels.. with built-in suspension =p

Post by paul18 »

hi

All have a look on your CAD, thanks.

I've a basic remark; I've had a fillet between the spokes and the outer diameter in order to decrease local stress (on the picture of the rover, I feel that chamfers have been added there)

Paul
thschrader
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Re: Inventing wheels.. with built-in suspension =p

Post by thschrader »

paul18 wrote: Wed Aug 30, 2017 2:51 pm
All have a look on your CAD, thanks.
To be clear:
It is not my invention, I have downloaded the model from page 1 (this thread).
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Re: Inventing wheels.. with built-in suspension =p

Post by thschrader »

paul18 wrote: Wed Aug 30, 2017 2:51 pm hi

All have a look on your CAD, thanks.

I've a basic remark; I've had a fillet between the spokes and the outer diameter in order to decrease local stress (on the picture of the rover, I feel that chamfers have been added there)

Paul
Hi Paul,
some thoughts about the wheel from the pic above deepsoic posted:
The trick seems to be, that the spokes are attached under 90 degree at cylinder/plate to avoid
high local stress. (forget the "red-zone" in my model, the shell is too thin at this position,
because I used surface-wb / extrude surface in y-direction. You will get a shell with variable thickness.
By constant thickness there should be no problems)
wheel_new.JPG
wheel_new.JPG (66.17 KiB) Viewed 2964 times
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