1. The problem statement, all variables and given/known data Determine the stresses and the change in length of the compound bar. compressive load F = 40kN Length L = 0.25m material (a) mild steel E = 205 GPa material (a) area = 0.04m^2 material (b) concrete E = 10 GPa material (b) area = 0.16m^2 For a similar example see example 2 of this PDF: http://fetweb.ju.edu.jo/staff/che/ymubarak/Strength-lectures/chapter2.pdf [Broken] My calculations so far are: (a) σ = 40/0.04 = 1000kNm^2 (b) σ = 40/0.16 = 250kNm^2 E=σ/ε → ε=σ/E (a) ε = 1000*10^3/205*10^9 = 4.9*10^-6 (b) ε = 250*10^3/10*10^9 = 25*10^-6 Free change in length = ΔL = ε*L (a) ΔL = 4.9*10^-6*0.25 = 1.2*10^-6m (b) ΔL = 25*10^-680.25 = 6.25*10^-6m After those calculations I am unsure what to do next to find the change in length in a joined compound bar. 2. Relevant equations See PDF 3. The attempt at a solution See above Thanks a lot for any help in improving my understanding of this.