Brake Worksheet

[blykins]

That's awesome then....when you look at a heat transfer balance, there's a fine line between temperatures. If you look at the thickness of a brake pad, one side should be a lot hotter than the other. That side of course would be the rotor side. The other side, which is exposed to air, would of course be cooler. So if your formula's solution is the temperature of the rotor side, then you can just plug and chug into my formula from above. Using the assumption that the part of the pad touching the rotor would be equal to the temperature of the rotor, and that heat is transferred through the thickness of the pad to the air that is flowing over it....you can solve the above formula for T2 (which is the temp of the pad facing the piston)....

(k(Tp-T2))/t = hA(T2-Tinf)

(k(Tp-T2))/t = hAT2 - hATinf

k(Tp-T2) = hAtT2 - hAtTinf

kTp-kT2 = hAtT2 - hAtTinf

kTp = hAtT2 - hAtTinf + kT2

kTp + hAtTinf = hAtT2 + kT2

kTp + hAtTinf = hAtT2 + kT2

kTp + hAtTinf = T2 (hAt + k)

T2 = (kTp + hAtTinf)/(hAt +k)

So you just plug your temperature result from your formula into Tp...Tinf would be the temperature of ambient air, you'll have to find h & k from a chart somewhere, A is the area of the pad, t is the thickness of the pad....and boom....you have the temp of the pad on the piston side.

Given that heat flux through the pad....once you know the temperature of each side, I can give you another formula will can show the temperatures at any point (x) in the pad...so you can see where the heat is the highest.....my guess is it would be highest right at the rotor, and then taper off through the cross section of the pad.

I'm sorry for all the babbling....like I said, I'm having to remember this as I go...it's been awhile. But the above stuff should get you going. Oh yeah, temperatures are in Kelvin.... h is in W/m^2 and k is in W/m*K.