고체역학 (Beer) — Pure Bending: Problem 4.87

4.87 For the beam indicated, a couple of moment equal to the full plastic moment \( M_p \) is applied and then removed. Using a yield strength of 240 MPa, determine the residual stress at \( y = 45\text{ mm} \). The beam indicated is the beam of Prob. 4.73. From Prob. 4.73: The beam has a rectangular cross section with width \( b = 60\text{ mm} \) and height \( h = 90\text{ mm} \). The material is elastoplastic steel with \( E = 200\text{ GPa} \) and \( \sigma_Y = 240\text{ MPa} \).