In a laboratory test of a beam loaded by end couples, the fiber at layer AB as shown are found to increase 40x 103 mm while those at CD decrease 70 x 10 mm in the 250-mm-gage length. Using E 150 GPa, -3 determine the flexural stress at the top fiber. Answer must be in MPa. Given: a 60 mm, b 120 mm, and c- -80 mm. gage length a mm A 8. b mm c mm

H.W 3 Two aluminum alloy plates (2) are attached to the sides of a wooden beam (1) as shown in Figure 3. mensions of the composite cross section are bj = 80 mm, d1 = dz 240 mm, b2 = 10 mm, d2 = The di- di %3D %3D 120 mm, and a = 60 mm. Deter- (2) (2) (1) mine the maximum bending stresses produced in both the wooden beam and the aluminum b1 plates if a bending moment M = +6,000 N m is applied about the z axis. Assume that E = 12.5 GPa and E2 = 70 GPa. FIGURE 3 %3D