calling designers and mechanical engineers - brake rotor design (heat transfer, thermal stress)
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calling designers and mechanical engineers - brake rotor design (heat transfer, thermal stress)
hello,
I'm about to design a brake rotor for my Formula SAE team and for my FEA class project.
It will be the rear rotors on our car. It will be a floating design attached to steel stub shafts that come out of our differential.
I have the proper methods to size the rotor, caliper, etc from vehicle dynamics theory. It should come out to 6-8 in diameter.
I have a good feeling on estimating the heat transfer and convection coefficients as well.
Since our main events do not result in much brake heat, I am aiming to go for the min. thickness our caliper (probably Wilwood kart caliper) can handle, which is .12 in.
I plan to use I-DEAS for structural and thermal analysis.
And now my question: how much material can one take off the rotor with consideration to proper functioning of the brake pad? Is there are certain amount that will just tear up the pad? I have seen british hillclimb cars with fairly large and thick arcs cut out of the rotor, leaving more area in holes than there was in material. Im concerned that when the brakes are applied and the pad contacts, if it catches one of these large edges it may wear extremely quickly. This is something I can't calculate and dont have the experimental means to analyze, so any input would be appreciated.
I'm about to design a brake rotor for my Formula SAE team and for my FEA class project.
It will be the rear rotors on our car. It will be a floating design attached to steel stub shafts that come out of our differential.
I have the proper methods to size the rotor, caliper, etc from vehicle dynamics theory. It should come out to 6-8 in diameter.
I have a good feeling on estimating the heat transfer and convection coefficients as well.
Since our main events do not result in much brake heat, I am aiming to go for the min. thickness our caliper (probably Wilwood kart caliper) can handle, which is .12 in.
I plan to use I-DEAS for structural and thermal analysis.
And now my question: how much material can one take off the rotor with consideration to proper functioning of the brake pad? Is there are certain amount that will just tear up the pad? I have seen british hillclimb cars with fairly large and thick arcs cut out of the rotor, leaving more area in holes than there was in material. Im concerned that when the brakes are applied and the pad contacts, if it catches one of these large edges it may wear extremely quickly. This is something I can't calculate and dont have the experimental means to analyze, so any input would be appreciated.
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Re: calling designers and mechanical engineers - brake rotor design (NegativeLift)
Be sure to check these out:
http://www.autointell.com/news...5.htm
http://www.sae.org/automag/tec...6.pdf
http://www.autointell.com/news...5.htm
http://www.sae.org/automag/tec...6.pdf
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From: 8 blocks from George Bush, DC
Re: calling designers and mechanical engineers - brake rotor design (NegativeLift)
Someone's already done the engineering for you.....
Check out some hydraulic disc brakes for mountian bikes. Most use 6 or 8 inch rotors and already have weight saving holes/slots in the rotors. Most save weight by using titanium bolts, kevlar brake lines (vs. steel braided), aluminum master cylinders.
There's one company that sell aluminum rotors for extra weight savings. You have to use a special brakepad so as to not prematurely wear out the aluminum rotor.
http://www.notubes.com/rotorsandbrakes.htm
Some mountain bike disc brakes:
http://www.cambriabike.com/bra...s.htm
Check out some hydraulic disc brakes for mountian bikes. Most use 6 or 8 inch rotors and already have weight saving holes/slots in the rotors. Most save weight by using titanium bolts, kevlar brake lines (vs. steel braided), aluminum master cylinders.
There's one company that sell aluminum rotors for extra weight savings. You have to use a special brakepad so as to not prematurely wear out the aluminum rotor.
http://www.notubes.com/rotorsandbrakes.htm
Some mountain bike disc brakes:
http://www.cambriabike.com/bra...s.htm
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From: 8 blocks from George Bush, DC
Re: calling designers and mechanical engineers - brake rotor design (NegativeLift)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NegativeLift »</TD></TR><TR><TD CLASS="quote">hello,
It will be a floating design attached to steel stub shafts that come out of our differential. </TD></TR></TABLE>
If the brakes won't be generating much heat, then why go with a floating design?
It will be a floating design attached to steel stub shafts that come out of our differential. </TD></TR></TABLE>
If the brakes won't be generating much heat, then why go with a floating design?
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From: Marietta, Georgia, USA
Re: calling designers and mechanical engineers - brake rotor design (Another Drew)
you asked for opinions.. so here is a weird one...
I would do a 2 plate clutch design with a floating center section.
When you need to brake just engage it and it will provide braking force!
Why 2 plates? Because you only need 1 flywheel so might as well have 2!~
Will it overheat ? HIGHLY doubtful..
What will it weigh? well 2 copper disks or 2 kevlar discs would be less than any metal rotor!
Tell me what you guys think ? Its not like he is doing stop and go braking for 5 hours...
I would do a 2 plate clutch design with a floating center section.
When you need to brake just engage it and it will provide braking force!
Why 2 plates? Because you only need 1 flywheel so might as well have 2!~
Will it overheat ? HIGHLY doubtful..
What will it weigh? well 2 copper disks or 2 kevlar discs would be less than any metal rotor!
Tell me what you guys think ? Its not like he is doing stop and go braking for 5 hours...
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From: Fort Worth, TX
Re: calling designers and mechanical engineers - brake rotor design (Want2race)
Would be very hard to modulate a clutch-type braking system, which is an important aspect of any braking system.
Why do you want it as thin as possible? Just size the rotor for the proper thermal mass you think you'll need and then go from there based on diameter calculations.
Are you worried about rotating mass? Most FSAE cars I've seen would probably not notice the difference of about 1lb of iron on the rotor, and I don't think the average mountain bike rotor would last very long given the speeds and thermal stress a FSAE car would put on it.
Why do you want it as thin as possible? Just size the rotor for the proper thermal mass you think you'll need and then go from there based on diameter calculations.
Are you worried about rotating mass? Most FSAE cars I've seen would probably not notice the difference of about 1lb of iron on the rotor, and I don't think the average mountain bike rotor would last very long given the speeds and thermal stress a FSAE car would put on it.
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Re: calling designers and mechanical engineers - brake rotor design (Def)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Def »</TD></TR><TR><TD CLASS="quote">
Why do you want it as thin as possible? Just size the rotor for the proper thermal mass you think you'll need and then go from there based on diameter calculations.
</TD></TR></TABLE>
a 1lb weight savings may not always translate into noticeable results in performance, but a big part of the design judging is the car's weight and how low weight was achieved.
the same holds for the floating rotor design. although we may not see the conditions to warrant a floating design, the theoretical customer for the car may. these are the types of things that come up in design judging
Why do you want it as thin as possible? Just size the rotor for the proper thermal mass you think you'll need and then go from there based on diameter calculations.
</TD></TR></TABLE>
a 1lb weight savings may not always translate into noticeable results in performance, but a big part of the design judging is the car's weight and how low weight was achieved.
the same holds for the floating rotor design. although we may not see the conditions to warrant a floating design, the theoretical customer for the car may. these are the types of things that come up in design judging
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From: Marietta, Georgia, USA
Re: calling designers and mechanical engineers - brake rotor design (NegativeLift)
You could do a caliper from a Sport bike ! Usually like $40 on ebay..
As for modulating the clutch mechanism , I think it would be quite a lot easier than you think.
As for modulating the clutch mechanism , I think it would be quite a lot easier than you think.
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