Design a rigid flange coupling to transmit a torque of 25 kgf-m between two coaxial shafts. Shaft is made of alloy steel, flanges out of CI and bolts out of steel. 4 bolts are used to couple the flanges. Shafts are keyed to the flange hub. Permissible stresses are given below:
Shear stress on shaft = 10 kgf/ mm2
Bearing stress or Crushing stress on shaft
= 25 kgf /mm2
Shear stress on keys = 10 kgf / mm2
Bearing stress on keys = 25 kgf / mm2
Bearing stress on CI = 20 kgf / mm2
Shear stress on bolts = 10 kgf / mm2
After designing the various elements, make a neat sketch of the assembly indicating the important dimensions. Stresses developed the various members to be checked if thumb rules are used for fixing the dimensions.
Which one member of the coupling will you design as a slightly weaker element and why?