HW Problem 5: A 150 kW motor drives a hollow round shaft at 1,200 rpm. The outer diameter of the shaft is 100-mm and the inner diameter is 0.95*outer diameter. It is made of AISI 1050 WQ&T at 425- deg C.
HW Problem 5: A 150 kW motor drives a hollow round shaft at 1,200 rpm. The outer diameter of the shaft is 100-mm and the inner diameter is 0.95*outer diameter. It is made of AISI 1050 WQ&T at 425- deg C.
(a) Look online or the book and explain briefly what “WQ&T” in the material designation stand for, and how it is different than OQ&T. Which is stronger at the specified temperature?
(b) Determine the maximum torsional shear stress (Tau max) in the hollow shaft. Write the units. Hint: Use the kW power equation, find torque, and find J to find Tau max. Use N, mm, MPa.
(c) Determine the safety or no safety factor for static loading (ns) according to (i) Tresca theory, and (ii) von-Mises theory. Hint: Read Sy from table and then calculate Ssy by Tresca and von-Mises. Then use (ns,Tresca) = (Ssy,Tresca) / (Tau max); (ns,von) = (Ssy,von) / (Taumax).
(d) If the calculated safety factor is more than 4.0, what parameters would you change to bring it down below 4.0 (and of course, above 1.0)?
