Steel shaft deflection

[djs03824]

Hi,

I'm an Electrical Engineer trying to spec. a hardened, ground shaft (C1060 steel) that will go through an environmental chamber. The shaft will have a plate attached holding some items to be electrically tested, that have to be positioned at precise angles to get the required data.

Can someone help with the calculations to find shaft deflection? The shaft will be supported at both ends, with a 40 inch span between pillow block bearings. I was thinking perhaps a 1 inch diameter solid shaft as described above would be adequate? The total weight of the units and plate should be under 30 pounds. The plate (aluminum 30"L x 16"W x 0.25"Thk) will be attached to the shaft in 4 evenly spaced places.

Thanks in advance for taking your time to help me with this.

Dave

 

[RandyC]

The formula you'll want to use to find deflection is

Deflection= (W*(l^3))/(48*E*I)

Where W equals your 30lbs l is the length of your beam E is young's modulus (about 29.6e6 for most steels) and I is the moment of inertia of the cross section. I=(pi*(d^4))/64 where d is the diameter.

I ran the calc and got a deflection of about 0.0276in and the stress was just as small. Your 1" shaft is fine, in fact you could probably use a hollow tube and still be ok. Depends on your application and what materials you have on hand.

randyc

 

[RandyC]

One other thing, I made an assumption that the entire load was at the center for ease of calculation. This only makes my answer more conservative.

 

[RandyC]

One other thing, I made an assumption that the entire load was at the center for ease of calculation. This only makes my answer more conservative.