Beer & Johnston — Pure Bending: Problem 4.69

4.69 A solid square rod of side 0.6 in. is made of a steel that is assumed to be elastoplastic with \(E = 29 \times 10^6\) psi and \(\sigma_Y = 48\) ksi. Knowing that a couple M is applied and maintained about an axis parallel to a side of the cross section, determine the moment M of the couple for which the radius of curvature is 6 ft.