
Note that the rod gets longer even though it is in compression. The positive ΔT causes the rod to elongate, more than compensating for the contraction caused by the internal compression force.
Numeric values
Temperature change
ΔT = +20°C
Brass link (1)
L1 = 250 mm
A1 = 400 mm2
E1 = 105 GPa
α1 = 20.9 × 10-6/°C
Steel rod (2)
L2 = 250 mm
A2 = 706.86 mm2
E2 = 200 GPa
α2 = 11.7 × 10-6/°C