2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Get all your technical information about electric bikes here.
Buk___   10 kW

10 kW
Posts: 750
Joined: Jul 28 2017 5:59pm

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by Buk___ » May 04 2018 7:27pm

e-beach wrote:
May 03 2018 9:14pm
I am looking forward to tests with a Grin torques arms myself. Maybe using the type of fork that failed earliest.
I was hoping that by modelling Justin's failed attempt, and showing that the results of the simulation produced similar results, I might demonstrate the efficacy of simulation testing. To be convincing, I need more accurate data than I can extract from pictures. (Due to the loss-y nature of the jpg format, the best I can achieve is about ±0.5mm/20thou of accuracy on the dimensions, which isn't good enough to be convincing.)

If I could make the case for simulation testing, then I could offer to put some of his design variations through that testing and perhaps contribute by saving him some time/cost producing prototypes for destruction.

Real life is always the real test, but if you can narrow down the possibilities, and guide the design process by seeing where the failures are likely to occur, in software; it can save a lot of time and money in the real world.

e-beach   100 MW

100 MW
Posts: 2773
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by e-beach » May 04 2018 9:50pm

I agree that simulation can be very beneficial to a design concept. However, Grin already has the testing equipment and the torque arms. Acquiring a few used forks for the propose of testing the standard torque arm in comparison to the un-torqued-arm forks would be very easy. No need for computer input this time. Get comparable forks and slap on the Grin torque arms. Torque the nuts tight and torque away!

:D
Favorite Quote: "This is L.A., sugar. There is no 'over the top." --- Chris Erskine

Current build: Liahona w/ cheap front suspension and suspension seat post. Yescomusa 36v 800w generic front hub motor. 15ah Headway triangle mounted pack. Tronsung 30 amp,

Previous Build:1992 Trek Antelope 800 - Bone Crusher (no suspension) - Yescomusa 800 watt 36 volt front wheel kit. Don't do it! Get suspension!!!

Buk___   10 kW

10 kW
Posts: 750
Joined: Jul 28 2017 5:59pm

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by Buk___ » May 05 2018 6:13am

e-beach wrote:
May 04 2018 9:50pm
I agree that simulation can be very beneficial to a design concept. However, Grin already has the testing equipment and the torque arms. Acquiring a few used forks for the propose of testing the standard torque arm in comparison to the un-torqued-arm forks would be very easy. No need for computer input this time. Get comparable forks and slap on the Grin torque arms. Torque the nuts tight and torque away!

:D
You miss my point. But what's new.

e-beach   100 MW

100 MW
Posts: 2773
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by e-beach » May 05 2018 9:27am

Buk___ wrote:
May 05 2018 6:13am
......You miss my point. But what's new.
Oh, you made a point? Well, that was smart of you.

And here all I was calling for was an apples-to-apples comparison. I guess it was pretty stupid of me to call for an apples-to-apples comparison. :lol:

:D
Favorite Quote: "This is L.A., sugar. There is no 'over the top." --- Chris Erskine

Current build: Liahona w/ cheap front suspension and suspension seat post. Yescomusa 36v 800w generic front hub motor. 15ah Headway triangle mounted pack. Tronsung 30 amp,

Previous Build:1992 Trek Antelope 800 - Bone Crusher (no suspension) - Yescomusa 800 watt 36 volt front wheel kit. Don't do it! Get suspension!!!

User avatar
liveforphysics   100 GW

100 GW
Posts: 13987
Joined: Oct 29 2008 1:48am
Location: Santa Cruz, CA, USA

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by liveforphysics » May 05 2018 8:27pm

In forged dropouts it's difficult to model the real grain structure related strength, but you're right that simulation rocks for this sort of application, and optimizing with FEA is a huge time saver for getting things ballparked to begin tests.

Buk___ wrote:
May 04 2018 7:27pm
e-beach wrote:
May 03 2018 9:14pm
I am looking forward to tests with a Grin torques arms myself. Maybe using the type of fork that failed earliest.
I was hoping that by modelling Justin's failed attempt, and showing that the results of the simulation produced similar results, I might demonstrate the efficacy of simulation testing. To be convincing, I need more accurate data than I can extract from pictures. (Due to the loss-y nature of the jpg format, the best I can achieve is about ±0.5mm/20thou of accuracy on the dimensions, which isn't good enough to be convincing.)

If I could make the case for simulation testing, then I could offer to put some of his design variations through that testing and perhaps contribute by saving him some time/cost producing prototypes for destruction.

Real life is always the real test, but if you can narrow down the possibilities, and guide the design process by seeing where the failures are likely to occur, in software; it can save a lot of time and money in the real world.
Each carcinogen vapor exposure includes a dice roll for cancer.

Each mutagen vapor exposure includes a dice roll for reproductive genetic defects in your children.

Each engine start sprays them into a shared atmosphere which includes beings not offered an opportunity to consent accepting these cancer experiences and defective genetics life experiences.

Every post is a free gift to the collective of minds composing the living bleeding edge of LEV development on our spaceship.

Buk___   10 kW

10 kW
Posts: 750
Joined: Jul 28 2017 5:59pm

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by Buk___ » May 06 2018 9:18am

liveforphysics wrote:
May 05 2018 8:27pm
In forged dropouts it's difficult to model the real grain structure related strength...
Closed die forging -- hot or cold -- produces very desirable and repeatable grain structure:Image Image

Which is why it is used for the manufacture of the highest stressed component in ICE engines, the gudgeon pins; and even 1-piece performance crankshafts:Image

But die costs are huge and only make sense if you are manufacturing 10s of thousands.

User avatar
justin_le   10 MW

10 MW
Posts: 2152
Joined: May 28 2007 3:27am
Location: Vancouver
Contact:

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by justin_le » May 07 2018 1:05pm

Buk___ wrote:
Apr 28 2018 10:48pm
justin_le wrote:
Apr 03 2018 4:01am
Image
Justin, Any chance you could post a dimensioned version of this design?
Yes, for sure. Here is the dimensioned drawing of the axle itself showing the actual spline definition:
Axle Spline Drawing.jpg
Axle Spline Drawing.jpg (101.9 KiB) Viewed 598 times
I don't have a drawing handy of the torque arm itself since we just went straight from the 3D CAD to CAM on the CNC mill, but I can go ahead and have that made too. I'm quite interested as well in seeing what a detailed FEA shows in comparison to the actual real world testing.

Also, we received the first mini pilot batch of splined axles from MAC motors last week and they look good! (except for the thread pitch obviously being coarser than our specified 1.0mm)
5 pcs Splined Axles.jpg
5 pcs Splined Axles.jpg (101.55 KiB) Viewed 598 times
The additional bench testing will resume soon and we'll have more results data to share. Robbie will likely take over the posting on this thread as I've got a few other things to tend to this month!
Currently recovering from the Suntrip race on a back to back tandem solar powered row/cycle trike. 550 watt solar roof, dual Grin All Axle hub motors, dual Phaserunner controllers, 12 LiGo batteries, and a whole wack of gear.

Now back in Vancouver with my Big Dummy Frame (yes This One, thanks ES!) with Grin all-axle front hub, Phaserunner controller, and 52V 19Ah Cellman triangle pack
My website: http://www.ebikes.ca
Please contact via email, info@ebikes.ca, rather than PMs, which are disabled

Buk___   10 kW

10 kW
Posts: 750
Joined: Jul 28 2017 5:59pm

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by Buk___ » May 13 2018 7:57pm

justin_le wrote:
May 07 2018 1:05pm
I'm quite interested as well in seeing what a detailed FEA shows in comparison to the actual real world testing.
I've had to shrink this using lossy compression in order to get it down to a size that will upload here (the original 15MB), which has made it rather small and fuzzy, but you can still see:
  • The way the upper arm moves left relative to the lower.
  • The ring being forced open as the load increases.
  • Finally, the strain on the spline at 5 O'clock climbing rapidly, and finally shearing through.
I rate that a pretty darn close match.

The maximum torque that design can handle seem to be about 31-32N.m; but that's before any consideration is given to cyclic fatigue and strain hardening.
splinedTA[200N.m][opt].gif
splinedTA[200N.m][opt].gif (476.35 KiB) Viewed 503 times
Bigger, clearer version.

More to come, but its a nice validation of the methodology.

e-beach   100 MW

100 MW
Posts: 2773
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by e-beach » May 13 2018 9:51pm

Ok, nice work, and correct me if I am wrong,....Are we viewing your gif as from the inside of the torque arm that is next to the motor?

Also, where is the rest of the torque arm setup. You seem to be missing a plate.

:D
Favorite Quote: "This is L.A., sugar. There is no 'over the top." --- Chris Erskine

Current build: Liahona w/ cheap front suspension and suspension seat post. Yescomusa 36v 800w generic front hub motor. 15ah Headway triangle mounted pack. Tronsung 30 amp,

Previous Build:1992 Trek Antelope 800 - Bone Crusher (no suspension) - Yescomusa 800 watt 36 volt front wheel kit. Don't do it! Get suspension!!!

Buk___   10 kW

10 kW
Posts: 750
Joined: Jul 28 2017 5:59pm

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by Buk___ » May 13 2018 10:06pm

e-beach wrote:
May 13 2018 9:51pm
Ok, nice work, and correct me if I am wrong,....Are we viewing your gif as from the inside of the torque arm that is next to the motor?
No. If you follow the link to the bigger version, it also includes a ghost of the axle that shows the view is from the outside.

If you're worried about the direction of rotation, imagine you are leaning over the bike from t'other side and looking at it upside down :)
e-beach wrote:
May 13 2018 9:51pm
Also, where is the rest of the torque arm setup. You seem to be missing a plate.
You'll have to imagine it :)

In this simulation, the arm is fixed by the inner face of the hole in the lower arm (as viewed in the gif) and the inner face of the hole in the upper arm, which is allowed to flex (a small amount) relative to the lower arm. This allows the twist, due to the clearance around the pinch bolt and the deformation that occurs there in real-life, without making the model so complex that it requires hours to run.

In anycase, as Jason's tests show, that extra plate made little or no difference.

e-beach   100 MW

100 MW
Posts: 2773
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: 2018 Torque Arm Tests, Splined Interface Design and Tabbed Washers

Post by e-beach » Aug 01 2018 5:02pm

So what was the final outcome of this tread?

:D
Favorite Quote: "This is L.A., sugar. There is no 'over the top." --- Chris Erskine

Current build: Liahona w/ cheap front suspension and suspension seat post. Yescomusa 36v 800w generic front hub motor. 15ah Headway triangle mounted pack. Tronsung 30 amp,

Previous Build:1992 Trek Antelope 800 - Bone Crusher (no suspension) - Yescomusa 800 watt 36 volt front wheel kit. Don't do it! Get suspension!!!

Post Reply