Question

An aluminium alloy rod has a length of 200 mm and a diameter of 10 mm.When subjected to a compressive force the length of the rod is 199.6 mm. Determine (a) the stress in the rod when loaded, and (b) the magnitude of the force. Take the modulus of elasticity for aluminium alloy as 70 GPa.

Answer 1

(a) Original length of rod, L = 200 mm, final length of rod = 199.6 mm, hence contraction, x = 0.4 mm. Thus, strain, 

= 7.854 × 10⁻⁵ m²

Hence, compressive force

F = σ A = 140 × 10⁶ × 7.854 × 10⁻⁵

= 11.0 kN