1. The problem statement, all variables and given/known data A composite shaft consists of a brass bar 50mm in diameter and 200mm long, to each end of which are concetrically friction-welded steel rods of 20mm and 100mm long. During a tensile test to check the welds on the composite bar, at a particular stage the overall extension is measured as 0.15mm. What are the axial stresses in the bar given that Ebrass=120Gpa and Esteel=208 Gpa. 2. Relevant equations Equations of equilibrium Equations to describe the geometry of deformation Stress-strain relationships. 3. The attempt at a solution For the bar, the equations of equilibrium is that the total force is the same as force exerted on steel bar and brass bar. The overall change in length must the sum of the change in rod 1 (steel), rod 2(brass) and rod 3(steel). Stress strain equations are: E=Stress/Strain for each rod (material) Ive got this far but there seem to always be too many unknowns in the problem to solve for stress in each rod? Many thanks for your help.