A circular steel rod AB (diameter d1 = 1.0 in., length L1 = 3.0 ft) has a bronze sleeve (outer diameter d2 = 1.25 in., length L2 = 1.0 ft) shrunk onto it so that the two parts are securely bonded (see figure).
Calculate the total elongation δ of the steel bar due to a temperature rise ΔT = 500°F. (Material properties are as follows: for steel, Es = 30 × 106 psi and αs = 6.5 × 106 / °F; for bronze, Eb = 15 × 106 psi and αb = 11 × 106 / °F.)

d2