고체역학 (Beer) — Torsion: Problem 3.103

3.103 A 1.25-in.-diameter solid circular shaft is made of a material that is assumed to be elastoplastic with \(\tau_Y = 18 \text{ ksi}\) and \(G = 11.2 \times 10^6 \text{ psi}\). For an 8-ft length of the shaft, determine the maximum shearing stress and the angle of twist caused by a 7.5-kip·in. torque.