A designer makes a 4-ft driveshaft from steel (E = 29 Msi, p = 0.00883 sl/in.3). The shaft has a 3-in. outer diameter and a wall thickness of 1/8 in. Calculate the critical speed of the shaft. Assume the shaft is simply supported. (Answer: 5800 rpm.)
The designer decides to switch to aluminum for the shaft (E = 10 Msi, p = 0.00305 sl/in.3). The size of the shaft remains the same. Calculate the new critical speed. (Answer: 5795 rpm.)