drivetrain

[sahil]

I am a beginner ,and i need to know whether hollow axles can be used and if yes,probably what material should i use.

[sahil]

I am a beginner ,and i need to know whether hollow axles can be used and if yes,probably what material should i use.

[Kirby]

I personally have seen it done.

Many materials are possible:
Carbon Fibre (RMIT)
Aluminium (UNSW)
4140 (whole bunch of people)

Materials choice depends on your selection criteria and mechanics analysis of the problem.

With your analysis it should be possible to determine an adequate cross-section for the specifics of the load.

Then you figure out if a hollow section has any benefits.

[sahil]

@ kirby
can aluminuim be used as a material for axles....has any one done it....please give me any information on this if u have....

[exFSAE]

Engineers have calculated shear stresses for years, yes. You can do the same!

T*r / J, bro.

[Brian Schien]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by sahil:
@ kirby
can aluminuim be used as a material for axles....has any one done it....please give me any information on this if u have.... </div></BLOCKQUOTE>

I saw a team do it. The first time they tried to drive the car it was heading up hill when they let the clutch out it started rolling backwards. So my engineering judgment tells me its not a good Idea.

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Brian Schien:
I saw a team do it. The first time they tried to drive the car it was heading up hill when they let the clutch out it started rolling backwards. So my engineering judgment tells me its not a good Idea. </div></BLOCKQUOTE>

I've seen a lot of steel halfshafts break also. Does that mean you shouldn't steel either?

[The AFX Master]

Titanium is also a wonder.. but it will break your wallet and your cost report. And if you're not careful, being Ti notch sensitive (correct me if i'm wrong, i think i did read something like that at the forum), you can end breaking the Ti shaft at splines. nevertheless a bad heat treated and/or machined 4340 shaft will fail anyways

[Kirby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Brian Schien:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by sahil:
@ kirby
can aluminuim be used as a material for axles....has any one done it....please give me any information on this if u have.... </div></BLOCKQUOTE>

I saw a team do it. The first time they tried to drive the car it was heading up hill when they let the clutch out it started rolling backwards. So my engineering judgment tells me its not a good Idea. </div></BLOCKQUOTE>

Thats where good analysis is important.

on the same comment as mtg, there was those bad batch of professionally made steel taylor race drive shafts that weren't heat treated properly and had a tendency to twist quite badly.

All the examples I cited above I witnessed working quite well.


Sahil,

I'm going to assume that when I mentioned aluminium axles in my original post you didn't realise I also cited a team; UNSW.

Thats probably my fault, for not being "international specific".

From my own photo collection here is the University of NSW team car ('06 I think), they have successfully run this arrangement for several years.

http://img102.imageshack.us/img102/4492/img0651je1.jpg

Please note: While I am (and most people here) are happy to share information of this nature, you will definitely not find people on this board to do work for you. And you will be informed of this if you ask.

That said I hope that this thread has got some cogs turning in your head so you can actually go do some engineering on the subject.

EDIT: And while we are on the subject, in the hopes of improving the quality of this board, please work on making your post titles more descriptive in the future.

[Tom W]

@ Brian we have run aluminium driveshafts since I believe 2001, with proper testing there is absolutely no reason that it cannot be done in a simple manner.

@ Kirby, close, its actually our 2005 car.

[The AFX Master]

What about weight?, compared to a standard 3/4" x20" hollow steel driveshafts? (9mm hole)..as for example these made by Taylor Race?.. Seems interesting http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

I don't see the pic very well, do you weld the shaft to the CV plate or that have some sort of spline or such?

[TG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kirby:

http://img102.imageshack.us/img102/4492/img0651je1.jpg

</div></BLOCKQUOTE>

Tom, a little off topic here but seeing this I must asked if you have noticed any side loads from the flex joints you're using? The reason I ask is that the carriers (more specifically their attachment) do not look like they'd be able to handle any lateral loading of any kind.

[Tom W]

The shafts are welded to the endplates. There is a non-trivial lateral load carried by the endplates, but I should point out that endplates made to that design from 5000 series aluminium have been perfectly useable for many times the length of an enduro run.

[sahil]

CAN ANY ONE SUGGEST ME SOME BOOK WHICH I CAN READ AND KNOW ABOUT THE BEST MATERIAL THAT I CAN USE FOR MY AXLES

[Mike Macie]

Any engineering mechanics book will help you to calculate the stresses involved. You can't just pick a good material and hope it doesn't fail. That's not how engineering is done.

[sahil]

thanx a lot for the help......

[ben]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by sahil:
CAN ANY ONE SUGGEST ME SOME BOOK WHICH I CAN READ AND KNOW ABOUT THE BEST MATERIAL THAT I CAN USE FOR MY AXLES </div></BLOCKQUOTE>

You're at Uni right? basic engineering shouldn't be taught to you on a forum.

What's the load? Determine a part geometry, calculate the stresses add a safety factor. Will the stuff yield? Even if it doesn't yield is it stiff enough?

Repeat for each component and you'll soon have a car...

Ben

[Kirby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom W:
@ Brian we have run aluminium driveshafts since I believe 2001, with proper testing there is absolutely no reason that it cannot be done in a simple manner.

@ Kirby, close, its actually our 2005 car. </div></BLOCKQUOTE>

Dammit. I should label my photos better.

Thinking about it, was it in '06 that you moved to a spool (the "infinite-bias-diff"). I'm trying to remember...the rear bulkhead design was quite different as well.

I do remember talking at length with your drive-line guy about the flex-plates.

[VFR750R]

Aluminum can be used. Proper drivetrain engineering always results in solid steel shafts for 3 reasons.
1) For the same torsional strength, solid driveshafts have the least torsional stiffness. This decreases transmission and other drivetrain stress, which increases reliability and decreases required weight elsewhere.
2) Heat treated steel can be much more then 3 times stronger per lb then aluminum but still only weighs 3 times more.
2b)Higher yield strength means smaller diameter, lower stiffness shafts still meeting strength requirement. Basically back to #1.
3) Additonal treatments can be done to steel like shotpeening, carbonizing, and nitriding that can build compressive stresses into the material and make the higher stressed area (surface) even stronger for even more additional strength and fatigue resistance. Back to #1.

[Tom W]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kirby:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom W:
@ Brian we have run aluminium driveshafts since I believe 2001, with proper testing there is absolutely no reason that it cannot be done in a simple manner.

@ Kirby, close, its actually our 2005 car. </div></BLOCKQUOTE>

Dammit. I should label my photos better.

Thinking about it, was it in '06 that you moved to a spool (the "infinite-bias-diff"). I'm trying to remember...the rear bulkhead design was quite different as well.

I do remember talking at length with your drive-line guy about the flex-plates. </div></BLOCKQUOTE>

Yep 2006 was the first year with the spool and the bulkhead went on a reasonable diet as well.

[RiNaZ]

tom, do you machined your bulkhead or casting?

[Brian Schien]

I should clarify the axels I saw brake were a terrible l design from the start they were 1.5 OD .125 wall with steel inserts bonded in the end and one .25 roll pin going trough it. The bond of the glue broke and the pins tore out of the holes as soon as power was applied.

Our drive train had four shafts two Taylor axles and two made shafts built from 4340. Next year I will build everything from 300m that's what the Taylor axels are built from.

[Tom W]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RiNaZ:
tom, do you machined your bulkhead or casting? </div></BLOCKQUOTE>

Machined on a 3 axis CNC mill.

[drywater]

guys i had a query related to manufacturing of hollow driveshafts,if the outer dia of splines is less than minor dia of hollow shaft or dia of splines is in between major and minor dia of hollow shafts then you would weld the splines to a hollow pipe or what is the other alternative??

ankit dhingra
www.defianzracing.in (http://www.defianzracing.in)
delhi college of engineering

[SNasello]

If i understand what you are saying here, it sounds like you are trying to weld a spline section with OD less than the OD of the shaft? If this is the case there is a good chance the driveshaft will break (depending on the diameter, if it is large enough than maybe not) and it will brake right at the weld. The weld fillet will create a huge stress riser right at the heat affected zone.

The weakest point is going to be the smallest part of the shaft and the stress riser is not going to help. you might as well weld the spline to a tube that has the same or smaller OD than the minor diameter of the splines.

Welding driveshafts isnt exactly the best engineering practice.

[The AFX Master]

Welding shafts is like having a chassis welded with chewing gum instead of filler steel rods.

Your driveshaft OD needs to be slightly less than the cv joint spline root diameter. And the transition between shaft and spline must bee smooth without indentations from spline machining!!.. or your shaft will fail due to high shear stress concentrations on the spline root (remember that shafts also have shear stress directed axially on all the radial planes)

Also you need to design (or ask/find) a proper heat treatement/surface finish. Normally you'll need a softer core and a harder surface. You can achieve that with a proper quenching & tempering. To improve fatigue life and prevent crack propagation, a shoot peen will do the job.

Never make half holes (those that don't pass through the whole shaft) that induces insanely high stress concentrations and get weird with the heat treatment.

[drywater]

so guys if the outer diameter of splines is more than the major diameter of the hollow shaft,then it has to be in one piece(results in no welding),another query is that for that hollow shaft do i have to bore a solid shaft or do i start with a pipe.(because straight boring is very difficult to attain in india).
another query is that if i have a hollow shaft how do i incorporate the plunging system .

[SNasello]

There is no point in making the OD of the shaft bigger than the OD of the major (or even minor) diameter of the splines. It will break at the smallest diameter. Additionally, the difference in diameter will cause a stress riser which will cause it to fail in that area.

On top of the stress riser, the heat affected zone will be weaker than the body of the shaft. It is generally not good practice to weld driveshafts, but if you do, making the diameters different on either side of the weld will only make things worse.

[The AFX Master]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">(or even minor) diameter of the splines. It will break at the smallest diameter. </div></BLOCKQUOTE>

That isn´t true at all, If you machine the splines (that´s not the better way to do so, but if you can´t make them via plastic deformation... you end machining them) the spline mill can left some little indentations on the smooth part of the shaft, because of that you´ll need to machine it slightly to a lesser diameter. See the Taylor race shafts. the shaft OD is less than the spline root.. that´s to avoid stress concentrations on spline transition to shaft

[SNasello]

Yes i appologize, the spline will also cause a stress riser. I was referring to a shaft with changing diameter, the smaller diameter will be significatly weaker. When you have a spline it is something else to consider.

[kracer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RiNaZ:
tom, do you machined your bulkhead or casting? </div></BLOCKQUOTE>

That's machined there buddy.
With a some kind of surface finish.

[nowhere fast]

The surface finish is from sandblasting.

Any other questions?

[rjwoods77]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by nowhere fast:
The surface finish is from sandblasting.

Any other questions? </div></BLOCKQUOTE>

How did those TORQdiscs perform?

[nowhere fast]

They worked very well. The overall driveline package is very light, and the design and manufacture of the components needed to accommodate the discs is probably simpler than for CV’s (although I don’t have first-hand experience with CV’s). The few failures we had were traced to mistakes made on our end (loose bolts, design flaws, etc.).

There are some drawbacks though: their large diameter makes packaging more difficult, and their stiffness contributes to the wheel rate.