Handouts
LINK: Shaft Design
Topics:
Shaft Design
Power Transmitted by Shafts
Emperical Formula from Machinery’s Equation
Exercises
|
1. A solid steel shaft whose Sy=280 MPa and Su=380 MPa, is used to transmit 320 kW at 850 rpm. Determine the shaft diameter. a. 38.2 mm b. 40.3 mm c. 35.1 mm d. 45.2 mm 2. A line shaft has a diameter of 55 mm when its speed is 480 rpm. If the shaft stress is 40 MPa, determine the shaft power transmitted. a. 60.5 hp c. 68.2 hp d. 73.4 hp 3. A short shaft has a diameter of 60 mm and delivers 120 kW power. Find the shaft speed. a. 463.7 rpm b. 422.8rpm c. 500.5 rpm d. 440.8 rpm 4. A main shaft has a diameter of 3.5 in and speed of 630 rpm. Calculate the possible power that the shaft can deliver. a. 282.6 hp b. 312.5 hp c. 337.6 hp d. 352.8 hp 5. A 3-in diameter line shaft is mounted with 18-in diameter pulley and transmits 130 HP. Find the tangential speed of the shaft, in m/s. a. 5.8 b. 7.6 c. 8.1 d. 6.2 6. A 60-mm diameter steel shaft is subjected to a 1800 kN-mm torque. Calculate the torsional deflection, in degrees per meter. Let G=80 GPa. a. 2.8 b. 3.3 c. 1.8 d. 1.0 7. Compute for the twisting moment, in in-lb developed when the shaft delivers 30 hp at 1300 rpm. a. 1256 b. 1658 c. 1805 d. 1454 8. A hollow shaft has an outside diameter of 5-in and an inside diameter of 3.5-in. Determine the diameter of solid shaft with equal strength in torsion. a. 3.3-in b. 5.2-in c. 6.1-in d. 4.6-in 9. A 1/4-in steel shaft transmits 28 in-lb torque. The effective length of the shaft is 10-in, the modulus of elasticity in shear is 11,000,000 psi. Find the angular deflection, in degrees. a. 2.5 b. 4.0 c. 3.0 d. 3.8 10. A solid shaft rotates at 120 rpm and transmits a torque of 100 N-m. The allowable shear stress is 50 MPa. Find the minimum diameter. a. 16.2 mm b. 21.7 mm c. 24.8 mm d. 27.8 mm 11. A 15-ft shaft is running at 280 rpm. What power this shaft could safely deliver. a. 13.9 hp b. 14.2 hp c. 16.5 hp d. 23.8 hp 12. A shaft has a length of 8 ft. Calculate the diameter of the shaft. a. 0.8451-in b. 0.6721-in c. 0.7055-in d. 0.4561-in 13. A 120 mm diameter shaft is subjected to a torque of 8 kN-m and bending moment of 3 kN-m. Find the maximum bending stress developed. a. 34 MPa b. 28 MPa c. 36 MPa d. 30 MPa 14. A machine shaft is supported by bearings 1.5 m apart and is to transmit 200 kW at 280 rpm while subjected to a bending load of 600 kg at the center. If the shearing stress is 45 MPa, determine the shaft diameter. a. 88 mm b. 93 mm c. 95 mm d. 98 mm 15. A motor is used to drive a centrifugal pump that discharges 3700 L/min at a head of 7.5 m. the pump efficiency is 65% and running at 520 rpm. Find the torsional stress of the shaft if the shaft diameter is 40 mm. a. 0.148 MPa b. 8.7 MPa d. 13.2 MPa 16. A 2.5-in diameter solid shaft is desired to replace a hollow shaft having 3.5-in outside diameter. Consider the strength to be the same, determine the inside diameter of hollow shaft. a. 2.5-in b. 3.1-in c. 4.3-in d. 5.5-in 17. A 1.8-in diameter short shaft is used to transmit 45 HP, determine the shaft speed. a. 5 rps b. 4 rps c. 6 rps d. 7 rps 18. A main shaft has 60 mm diameter running at 280 rpm. What is the power that can be delivered by the shaft? a. 42.2 hp b. 46.1 hp c. 52.9 hp d. 38.6 hp 19. What is the diameter of the line shaft that transmits 180 kW at 20 rps? a. 3.1-in b. 4.8-in c. 2.8-in d. 2.2-in 20. Calculate the maximum unit shear in a 3-in diameter steel shafting that transmits 25,000 in-lb of torque at 130 rpm. a. 3218.6 psi b. 5518.5 psi c. 3889.3 psi d. 4715.7 psi 21. A solid shaft 5 m long is stressed to 80 MPa when twisted through 5 degrees. Find the shaft diameter if G=90 GPa. a. 95.2 mm b. 120.5 mm c. 102.0 mm d. 115.8 mm 22. What is the minimum diameter of a steel shaft which will be used to operate 15 kN-m torque and will not twist more than 4 degrees in length of 8 m? (G=85 x 106 kPa) a. 120 mm b. 115 mm c. 125 mm d. 110 mm 23. A force tangent to 1 foot diameter pulley is 6 kN and is mounted on a 2.5-in shaft. Determine the torsional deflection if G = 83 x106 kPa. a. 0.28 deg/m b. 0.11 deg/m c. 0.33 deg/m d. 0.40 deg/m 24. What is the polar moment of inertia of a solid shaft that has a torque of 2 kN-m and a stress of 28 MPa. a. 1.5x10-6 m4 b. 2.5x10-6 m4 c. 3.2x10-6 m4 d. 2.0x10-6 m4 25. A hollow shaft that has 110 mm outside diameter and 90 mm inside diameter is used to transmit 120 kW at 700 rpm. What is the shaft stress?
a. 8.5 MPa b. 11.4 MPa c. 14.8 MPa d. 18.8 MPa 26. A hollow shaft developed a torque of 6 kN-m and shaft stress of 50 MPa. If the outside diameter of the shaft is 90 mm, find the shaft inner diameter. a. 50.1 mm b. 57.0 mm c. 62.3 mm d. 68.8 mm 27. A shaft of a motor has a length of 20 times its diameter and has a maximum twist of 1-degree when twisted at 2.5 kN-m torque. If the modulus of rigidity of the shaft is 80 GPa, determine the shaft diameter. a. 71.6 mm b. 60.8 mm c. 75.8 mm d. 78.5 mm 28. A steel shaft transmits 60 HP at 1500 rpm. If the allowable stress is 550 psi, find the shaft diameter. a. 2.9-in b. 3.2-in c. 4.8-in d. 3.6-in 29. What is the speed of 64 mm shaft that transmits 80 kW if the stress is not to exceed 30 MPa. a. 387.2 rpm b. 494.7 rpm c. 521.8 rpm d. 455.7 rpm 30. A shaft has an ultimate stress of 380 MPa and has a design factor of 4. The torque developed by the shaft is 4 kN-m and the outside diameter is 90 mm. Compute the inside diameter of the shaft. a. 65.3 mm b. 73.8 mm c. 88.4 mm d. 82.5 mm 31. Find the diameter of a steel shaft which will be used to operate a 120 kW motor rotating at 6 rps and with a torsional stress is 100 MPa. a. 38.2 mm b. 48.8 mm c. 58.5 mm d. 54.5 mm 32. A shaft is used to transmit 230 kW at 380 rpm by means of 210 mm diameter sprocket. Determine the force tangent to the sprocket. a. 48.2 kN b. 50.8 kN c. 55.0 kN d. 62.8 kN |
Torsional Stress on Shafts
A centrifugal pump is connected to a motor by means of a coupling. The pump is rated at 3700 Liters per minute. Against a head of 7.50 m. The efficiency of the pump is 65% at the speed of 520 rpm. If the water is being pumped, calculate the torsional stress developed on the 40 mm motor shaft.
SOLUTION:
