Question

. A 25mm diameter rod is subjected to an axial load of 20 000N. If the material is elastic with a Young's Modulus of Elasticity E = 70,000Nmm-2 estimate the percentage elongation.

Answer 1

Solution.

$d=25mm;$

$F=20000N;$

$E=70000N/mm^2;$

$\sigma=\dfrac{F}{S};$

$S=\dfrac{\pi d^2}{4};$

$\sigma=E\epsilon\implies\epsilon=\dfrac{\sigma}{E};$

$S=3.14\sdot\dfrac{(25mm)^2}{4}=490.625mm^2;$

$\sigma=\dfrac{20000N}{490.625mm^2}=40.76N/mm^2;$

$\epsilon=\dfrac{40.76N/mm^2}{70000N/mm^2}=0.00058=0.058\%;$

Answer: $\epsilon=0.058\%.$