Problem 2 (15 points). Determine the factors of safety for the following plane stress states using the distortion-energy (DE) and maximum shear stress (MSS) theories, for ductile AISI 1020 cold-drawn steel with yield strength of 390 MPa in both tension and compression. (a) 180 MPa, y = 150 MPa, Try 0 (b) x=200 MPa, y = 0, Txy = 100 MPa (c) x = 0, y = 0, Txy = 140 MPa Problem 3 (15 points). Repeat Problem 2 graphically by plotting the yield envelopes using MATLAB for both theories. For plotting the DE theory envelope, you may use the MATLAB script (after making necessary changes) that I am going to e-mail/have e-mailed to you.