고체역학 (Beer) — Torsion: Problem 3.116

3.116 The solid shaft shown is made of a steel that is assumed to be elastoplastic with \(\tau_Y = 145\) MPa and \(G = 77.2\) GPa. The torque is increased in magnitude until the shaft has been twisted through \(6^{\circ}\); the torque is then removed. Determine (a) the magnitude and location of the maximum residual shearing stress, (b) the permanent angle of twist.