The composite bar in Fig. P-247 is stress-free before the axial loads P1 and P2 are applied. Assuming that the walls are rigid, calculate the stress in each material if P1 = 150 kN and P2 = 90 kN.
From the FBD of each material shown, δal is shortening, δst is lengthening, and δbr is also lengthening. Thus,