thermal expansion diameters

[metalwillow]

Can anyone point me in the right direction?
I need to calculate thermal expansion
of a shaft and a bushing with two different
materials.

 

[MechEng2005]

Try looking up "Coefficient of Thermal Expansion" on

http://www.wikipedia.org

This will give you equations and some basic coefficients needed for different materials.

 

[metalwillow]

Wikipedia doesn't explain it very well.
So this is how I understand it....
shaft od = 1.375 made of gray iron
coef of thermal expansion 5.8
heat 600c or 1112F

od x coef x 10-6 x 1112
so

1.375 x 5.8 x.000001 x 1112 = .0088
so the shaft expands .0088
Is this correct?
Does work the same for an inner diameter?

 

[prex]

Correct and it is exactly the same for an ID.

prex

http://www.xcalcs.com

: Online tools for structural design

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[Tomtation]

Almost correct. You calculate the thermal expansion based on the temperature difference. Usually from room temperature, 70 F. Therefore the calculation should be alpha x (T2 - T1) x length = 5.8 (10-6)in/in F x (1112 - 70)F x 1.375 in = 0.0083 in. Take note that all dimensions increase as temperature increases, ID, OD, length, etc.