고체역학 (Gere) — Torsion: Problem 3.8-5

3.8-5 A stepped shaft $ACB$ having solid circular cross sections with two different diameters is held against rotation at the ends (see figure). (a) If the allowable shear stress in the shaft is $43\text{ MPa}$, what is the maximum torque $(T_0)_{\max}$ that may be applied at section $C$? (b) Find $(T_0)_{\max}$ if the maximum angle of twist is limited to $1.85^\circ$. Let $G = 28\text{ GPa}$. Figure Values for Problem 3.8-5: Segment $AC$: diameter $d_1 = 20\text{ mm}$, length $L_1 = 225\text{ mm}$ Segment $CB$: diameter $d_2 = 25\text{ mm}$, length $L_2 = 450\text{ mm}$ Torque $T_0$ is applied at point $C$