In: Mechanical Engineering
12. Design a cast iron flywheel having six arms for a
four stroke engine developing 120 kW at 150 r.p.m.
The mean diameter of the flywheel may be taken as 3 metres. The
fluctuation of speed is 2.5% of mean
speed. The workdone during the working stroke is 1.3 times the
average workdone during the whole
cycle. Assume allowable shear stress for the shaft and key as 40
MPa and tensile stress for cast iron as
20 MPa. The following proportions for the rim and elliptical arms
may be taken:
(a) Width of rim = 2 × Thickness of rim
(b) Major axis = 2 × Minor axis