bolts/screws in shear 1

[TheReg]

Question:
I need some help finding the shearing stress of screws holding a shaft to a drum.

T = 6724.08 (lb in.)

Number of bolts = 6
Bolt Size = 5/16-18 X 1-1/2"
Plate thickness = .750
Bolt Circle = 2-7/8"

I know I can increase the size of the screws to 1/2" dia w/close fit holes, or better, and add two dowel pins to carry the shearing load. But cant recall the formula needed to determine if the load applied will shear the existing screws, or not.

Thanks in advance,
Doug

 

[desertfox]

Hi dougwdicar


Divide the torque by the radius of the bolt circle ie:-


6724.08/1.4375 = 4677.62087 lbs


therefore the mean shear stress in each of the bolts is:-



stress = 4677.62087/(6*3.142*0.3125^2/4)

stress = 10164.44905 lb/in^2 (shear)


in the formula 6= number of bolts and 0.3125 is bolt dia


hope this helps

regards desertfox

 

[TheReg]

Thanks, that twice you have been a help to me, I appreciate that.

Thanks,
dougwdicar