$$\begin{gathered} 20-\mathrm{mm} \mathrm{diameter} \mathrm{steel} \mathrm{rod} \\ \mathrm{A}=314.16 {\mathrm{mm}}^2 \\ \mathrm{E}=200 \mathrm{GPa} \\ \mathrm{\alpha }=12.0\times {10}^{-6}{/}^{\circ }\mathrm{C} \end{gathered}$$

After the temperature of the assembly has decreased by $32.8 {}^{\circ }\mathrm{C}$, a tension force of $\mathrm{F}=24,740 \mathrm{N}$ is induced in the steel rod. This force, in turn, pulls on the $15-\mathrm{mm}$ diameter bolt, creating a shear stress of $70 \mathrm{MPa}$ in the bolt.

Finished