Tube sizing

[KieranSean]

Hi Guys,

Can anyone take a look and comment on the attached spread sheet intended for sizing tube for basic low speed drive shafts. Just want to make sure i haven't missed anything. (intended application is to pin the tube between motor and valve shaft)

Cheers

Kieran

 

[Tmoose]

Is there a pin securing the constant section tubular shaft to the motor and pump shafts?
Similar to the joint on the left here ?

http://accessscience.com/loadBinary.aspx?aID=4386&filename=677800FG0010.gif

I'm thinking the local stresses there would be much higher than the basic stress in the tube due to transnmitted torque

 

[KieranSean]

Yes i will be using 2 x HBK spirol pins 90 degrees to one another. i've also sized these on the output torque of the motor using T=Fd with F being the double shear strength of the pin and d the diameter of the shaft.