Beer & Johnston — Pure Bending: Problem 4.19

4.19 and 4.20 Knowing that for the extruded beam shown the allowable stress is 120 MPa in tension and 150 MPa in compression, determine the largest couple M that can be applied. (Fig. P4.19 shows a trapezoidal cross-section with a top width of 80 mm, a bottom width of 40 mm, and a height of 54 mm.)