309 Finding the Diameter of a Propeller Shaft Transmitting a Power

Problem 309
A steel propeller shaft is to transmit 4.5 MW at 3 Hz without exceeding a shearing stress of 50 MPa or twisting through more than 1° in a length of 26 diameters. Compute the proper diameter if G = 83 GPa.

Solution 309



im confused on why do we need to use the larger diameter

Jhun Vert's picture

It is actually a good thing to ponder. It will be enjoyable and at your best advantage to reason it out yourself.

the outermost fiber of a material is where the shearing stress is at maximum that is why we always use the outside diameter of a shaft when dealing with torsion