Discs (rotors) made from?

[AndreZA]

And what happens when you upgrade to XTR?

 

 

 

 

that will never happen.

 

1. I don't have that money to waste

 

2. I don't like the looks of it

[parabola]

 

Plus if one really wants they can apply a "braking force" to see if the rotor design is prone to warp.

 

 

An accurate FEA on that rotor would be quite a task, especially regarding the approximation of the braking force. Would probably be best to model the braking force as a uniformly distributed load with point forces at each bolt hole.

 

[patches]

Plus if one really wants they can apply a "braking force" to see if the rotor design is prone to warp.

An accurate FEA on that rotor would be quite a task' date=' especially regarding the approximation of the braking force. Would probably be best to model the braking force as a uniformly distributed load with point forces at each bolt hole.
[/quote']

 

haha! I did the FEA on them... I specified that the 6 bolt holes be the fixed constraints, then applied a tangential point load to replicate the kind of torque that would be experienced by the rotor.

 

As for load figures, I based them on a report of a test that Cannondale did regarding disk braking forces.

 

Oh and Mampara, sorry I been outta touch... work has been crazy. But I have found out that 410 Stainless Steel is our best option, and is lighter and stronger than 304L (will find out cost). So we can shave a few more grams off

[parabola]

 

 

Plus if one really wants they can apply a "braking force" to see if the rotor design is prone to warp.

 

An accurate FEA on that rotor would be quite a task' date=' especially regarding the approximation of the braking force. Would probably be best to model the braking force as a uniformly distributed load with point forces at each bolt hole.

[/quote']

 

haha! I did the FEA on them... I specified that the 6 bolt holes be the fixed constraints, then applied a tangential point load to replicate the kind of torque that would be experienced by the rotor.

 

As for load figures, I based them on a report of a test that Cannondale did regarding disk braking forces.

 

For interests sake, what were the approximate braking forces?

You might also want to check where the tangential load is being applied, if its inbetween a 'spoke' of the disc it will affect it differently to being applied on or near a spoke. This becomes more important as the design craziness increases.

 

With regard to the bolt mounts, as long there is enough meat around them should be fine to use a fixed constraint. At any rate the safety factor on something like this would be high enough to give you some headroom with the FEA analysis.

parabola2010-02-23 04:47:32

[patches]

Plus if one really wants they can apply a "braking force" to see if the rotor design is prone to warp.

An accurate FEA on that rotor would be quite a task' date=' especially regarding the approximation of the braking force. Would probably be best to model the braking force as a uniformly distributed load with point forces at each bolt hole.
[/quote']

 

haha! I did the FEA on them... I specified that the 6 bolt holes be the fixed constraints, then applied a tangential point load to replicate the kind of torque that would be experienced by the rotor.

 

As for load figures, I based them on a report of a test that Cannondale did regarding disk braking forces.

For interests sake, what were the approximate braking forces?
You might also want to check where the tangential load is being applied, if its inbetween a 'spoke' of the disc it will affect it differently to being applied on or near a spoke. This becomes more important as the design craziness increases.
 
With regard to the bolt mounts, as long there is enough meat around them should be fine to use a fixed constraint. At any rate the safety factor on something like this would be high enough to give you some headroom with the FEA analysis.

 

If I remember correctly the figure was 1825N. I ran it through the stress analysis software on Inventor 2010 Pro (ANSYS). I should be getting ALGOR soon, and will check it again on there.

 

What sort of software are you using? If you'd like I can convert the model to an ACIS .SAT file and it can be imported into just about any FEA/FEM software.

 

But as great as all the software is... I think my best bet is to make a couple of prototypes and test them (with my helmet on ofcourse, haha!)

patches2010-02-23 04:57:16

[greatwhite]

Nice looking discs' date=' but structrually unsound - the open section at the end of the T (in XT) could be a problem - at the very least, you need to run these anti clockwise as viewing the top left view

[/quote']

it has already been virtually tested and found to be 100% safe. Just waiting for final numbers.

 

Sure? Thats one of the problems with FEA - people do it and think it excludes them from thinking about practical aspects of what they are doing:

 

Any of those pointed bits at the end of the 'T's get a small bump , they will get bent easily then the bent section jams into the side of the pad - result: FUBAR caliper, disc minimum. Close the top of the 'T' and suddenly it becomes significantly more resistant to this problem. FEA will never show you this

 

 

...........

 

Oh and Mampara' date=' sorry I been outta touch... work has been crazy. But I have found out that 410 Stainless Steel is our best option, and is lighter and stronger than 304L (will find out cost). So we can shave a few more grams off

[/quote']

 

410, she is lots of maaney.....

 

I'm no expert on 410, but just some thoughts: while 410 minimum yeild is 34% higher than 304/310/316 - typical values seem to be near enough the same (310 is actually best) so what real world benefit is there. Please don't tell me you plan to temper 410 to try to get the 1GPa+ yeild strength that is possible when done right.

 

Stick to 304 (or 310 of you feel a bit richer) not 304L. Low carbon grades of St/St typically have lower strength AND cost more.

 

As an aside - I did an equiry on Gr5 Ti the other day - It will cost about R500 a disc (?160) if you want to go really OTT

[patches]

Nice looking discs' date=' but structrually unsound - the open section at the end of the T (in XT) could be a problem - at the very least, you need to run these anti clockwise as viewing the top left view

[/quote']

it has already been virtually tested and found to be 100% safe. Just waiting for final numbers.

 

Sure? Thats one of the problems with FEA - people do it and think it excludes them from thinking about practical aspects of what they are doing:

 

Any of those pointed bits at the end of the 'T's get a small bump , they will get bent easily then the bent section jams into the side of the pad - result: FUBAR caliper, disc minimum. Close the top of the 'T' and suddenly it becomes significantly more resistant to this problem. FEA will never show you this

 

 

...........

 

Oh and Mampara' date=' sorry I been outta touch... work has been crazy. But I have found out that 410 Stainless Steel is our best option, and is lighter and stronger than 304L (will find out cost). So we can shave a few more grams off

[/quote']

 

410, she is lots of maaney.....

 

I'm no expert on 410, but just some thoughts: while 410 minimum yeild is 34% higher than 304/310/316 - typical values seem to be near enough the same (310 is actually best) so what real world benefit is there. Please don't tell me you plan to temper 410 to try to get the 1GPa+ yeild strength that is possible when done right.

 

Stick to 304 (or 310 of you feel a bit richer) not 304L. Low carbon grades of St/St typically have lower strength AND cost more.

 

As an aside - I did an equiry on Gr5 Ti the other day - It will cost about R500 a disc (?160) if you want to go really OTT

 

Yeah, I figured that 410 would affect the cost. I guess if it were easily available in SA it would be a different story. I've noticed that even Rav-X discs are 410.

 

Wasn't planning on tempering.... don't need that sort of strength. Was  more going for a combination of the slight strength increase and the lower density compared to the 304's.

 

I've got quotes on the cost of making 304L rotors. It's pretty decent... basically I can get 2 custon rotors made for around what a LBS would sell 1 of their cheapest rotors.

 

Thanks for the heads-up on going 304 vs. 304L. I just picked 304L cos we use it a lot at work... but the 304 sounds better

patches2010-02-23 07:22:01