고체역학 (Gere) — Torsion: Problem 3.4-4

3.4-4 A solid, circular bar ABC consists of two segments, as shown in the figure. One segment has a diameter of \(d_1 = 56\text{ mm}\) and length of \(L_1 = 1.45\text{ m}\); the other segment has a diameter of \(d_2 = 48\text{ mm}\) and length of \(L_2 = 1.2\text{ m}\). What is the allowable torque \(T_{\text{allow}}\) if the shear stress is not to exceed \(30\text{ MPa}\) and the angle of twist between the ends of the bar is not to exceed \(1.25^\circ\)? (Assume \(G = 80\text{ GPa}\).)