Design of Shafts

How will you design shaft on the basis of rigidity? Explain.

A line shaft supporting two pulleys A and B is shown in Figure 1. Power is transmitted to the shaft by means of a vertical belt on the pulley A, which is then transmitted to the pulley B carrying a horizontal belt. The ratio of belt tension on tight and loose sides is 3:1. The limiting value of tension in the belts is 2.7 kN. The shaft is made of plain carbon steel 40C8 (\(S_{ut}=650\text{ N/mm}^2\) and \(S_{yt}=380\text{ N/mm}^2\)). The pulleys are keyed to the shaft. Determine the diameter of the shaft. Dimensions in the figure are in mm.

A hollow shaft of 0.5 m outside diameter and 0.3 m inside diameter is used to drive a propeller. The shaft is mounted on bearings 6 m apart and transmits 5600 kW at 1500 rpm. The maximum axial propeller thrust is 500 kN and the shaft weighs 70 kN. Determine the maximum shear stress developed in the shaft. Assume the load is gradually applied.