Question

to my fellow mechanical engineers, please help me with some basic machine design problems.

a certain drive shaft rotating at 500 rpm transmits 200 hp to an 8 inch diameter gear. Design a suitable solid shaft for this application. the shaft is ductile. Design stresses are to be limited to Smax= 134 ksi and SHEAR max = 40 ksi

Answer 1

The highest grade of aluminum would be it best bet maybe air plane grade?

Answer 2

The best I can do is say to use

\[\tau=F/Ao\]
\[\tau=G * \gamma\]
where tau is shear, and G is shear modulus (a constant for each metal)

and

\[\sigma=\epsilon*E\] where E is modulus of elasticity (constant for each metal), sigma is stress, and epsilon is strain. For stress, you sub yield strength or tensile strength (given for each metal). If this is a real application use yield strength because that says when it will deform where tensile strength says where it will break. We don't want any deformity in a real application.

\[Ao = (do/2)^{2} \pi\]

This is all from a materials science POV, so please disregard if you are in a higher level than that.