Example. A steel rod, $1\mathrm{.}5$ m long and with a cross$-$sectional area of $200m{m}^2,$ is rigidly fixed at both ends. It is subjected to:

Tensile load of $20$ kN

Temperature increased from $15C$ to $50C.$

The rod is constrained, so it cannot expand or contract freely due to the temperature change.

E $=210$ GPa

Coefficient of thermal expansion for steel, $=12{10}^{-6}{C}^{-1}$

$-$Determine the total stress in the steel rod due to the combined effects of the axial load and the temperature change.