Compatibility Condition:
Total strain in steel = Total strain in copper
i.e. 3 × 10^{-4} + 1.965 × 10^{-5} P_{s} = 4.5 × 10^{-4} + 1.8421 × 10^{-5} P_{c}
Recognising that P_{c} = - P_{s}, and dividing both sides by 10^{-5}, we get
30 + 1.965 P_{s} = 45 - 1.8421 P_{s}
or Ps = 45 - 30/ (1.965 + 1.8421) = 3.94 kN
∴ Stress in steel = 3.94 × 1000/ (π/4) × 18^{2} = 15.5 N/mm^{2}
∴ Stress in copper = - 3.94 × 1000/ (π /4)(302 - 182) = - 8.71 N/mm^{2}