Bar AB has a cross-sectional area of 1200 mm2 and is made of a steel that is assumed to be elastoplastic with E = 200 GPa and σY = 250 MPa. Knowing that the force F increases from 0 to 520 kN and then decreases to zero, determine
(a) the permanent deflection of point C,
(b) the residual stress in the bar.
