고체역학 (Beer) — Torsion: Problem 3.19

3.19 Shaft AB is made of a steel with an allowable shearing stress of 90 MPa, and shaft BC is made of an aluminum with an allowable shearing stress of 60 MPa. Knowing that the diameter of shaft BC is 50 mm and neglecting the effect of stress concentrations, determine (a) the largest torque T that can be applied at A if the allowable stress is not to be exceeded in shaft BC, (b) the corresponding required diameter of shaft AB.