고체역학 (Beer) — Stress and Strain—Axial Loading: Problem 2.105

2.105 Rod \(ABC\) consists of two cylindrical portions \(AB\) and \(BC\); it is made of a mild steel that is assumed to be elastoplastic with \(E = 200 \text{ GPa}\) and \(\sigma_Y = 250 \text{ MPa}\). A force \(P\) is applied to the rod and then removed to give it a permanent set \(\delta_P = 2 \text{ mm}\). Determine the maximum value of the force \(P\) and the maximum amount \(\delta_m\) by which the rod should be stretched to give it the desired permanent set.