The design procedure is generally based on determining the shaft diameter 'd' for a given torque transmission. the different dimensions of the coupling are then obtained based on the shaft diameter using some empirical relations. check for different failure modes are then be carried out. design a typical rigid flange coupling for connecting a motor and a centrifugal pump shafts. the coupling needs to transmit 15 kw at 1000 rpm. the allowable shear stresses of the shaft, key and bolt materials are 60 mpa, 50 mpa and 25 mpa respectively. the shear modulus of the shaft material may be taken as 84gpa. the angle of twist of the shaft should be limited to 1 degree in 20 times the shaft diameter. due to some unavoidable condition, the coupling starts transmitting a varying load from 12.5 kw to 15 kw at 1000 rpm. redesign the centrifugal pump shaft and the corresponding components accordingly.