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

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.

@ 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....

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

T*r / J, bro.

quote:

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....

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.

quote:

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.

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

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

quote:

Originally posted by Brian Schien:

quote:

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....

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.

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.



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.

@ 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.

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

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?

quote:

Originally posted by Kirby:

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.

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.

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

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.

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

quote:

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

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

quote:

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.

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.

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.

quote:

Originally posted by Kirby:

quote:

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.

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.

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

tom, do you machined your bulkhead or casting?