3. An 8-inch diameter steel shaft is force fit into a cast iron disk with a 20-inch outside diameter. The maximum tangential stress in the disk is 5000 psi. If Esteel = 30x106 psi and Ecast iron = 15x106 psi, with Poisson’s ratio  for both materials equals to 0.3, (a) Determine the contact pressure required between the shaft and the disk (A: p  3621 psi ). (b) Determine the decrease in the radius of the shaft (A: ds = 0.00034 inch). (c) Determine the required diametral interference (A: 2 = 004 in. (Hint: A change in the shaft radius or diameter can be obtained through the displacement in the shaft)

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Aplate clutch has a single pair of mating friction surfaces 250-mm od by 175-mm id. the mean value of the coefficient of friction is 0.30, and the actuating force is 4 kn. a) find the maximum pressure and the torque capacity using the uniform-wear model. b) find the maximum pressure and the torque capacity using the uniform-pressure model.

Find the minimum film thickness for a journal bearing with the data below. shaft diameter, d-50 mm, clearance ratio, cdratio? 0.001, shaft speed, n 2000 rpm; bearing length. i 200 mm; eccentricity ration, ? -0.55. ( note, cdratio-ca/d) the minimum film thickness is um