Question

A steel bar is 3m in length and is subjected to an axial pull of 100kn .the bar is 40mm in diameter for a length of 0.8m and 20mm in diameter for the remaining length .find the total extension of the bar. Take modules. Of elasticity as 2×10

Answer 1

Explanation:

Load p =45 KN = 45 x 103 N

Young’s modulus E = 200 KN /mm2

Length of the rod, l = 500 mm

Diameter of the rod = 20 mm

Data asked:

Stress, strain, elongation CIRCULAR ROD

Solution:

Cross sectional area; A = πd2/4 =π x 202/4 = 314.159 mm2

Stress σ =load / area =45x103/314.5 = 143. 24 N/mm2

Strain, e = stress / young’s modulus =143.24/200x103 = 0.0007162

Elongation δl=Pl/AE = (45x103 x 500) / (314.159 x 200x103) = 0.358 mm

Result:

Stress σ = 143.24 N/mm2

Strain = 0.0007162

Elongation δl = 0.358 mm