고체역학 (Beer) — Stress and Strain—Axial Loading: Problem 2.101

2.101 The cylindrical rod \(AB\) has a length \(L = 5\text{ ft}\) and a \(0.75\text{-in.}\) diameter; it is made of a mild steel that is assumed to be elastoplastic with \(E = 29 \times 10^6\text{ psi}\) and \(\sigma_Y = 36\text{ ksi}\). A force \(P\) is applied to the bar and then removed to give it a permanent set \(\delta_P\). Determine the maximum value of the force \(P\) and the maximum amount \(\delta_m\) by which the bar should be stretched if the desired value of \(\delta_P\) is (a) \(0.1\text{ in.}\), (b) \(0.2\text{ in.}\)