Example $3$ :

A bi$-$metallic stepped rod ABCD has axial forces applied as shown.

Determine the internal axial loads in the rod and draw an axial force diagram for the rod.

The segment $AB$ has a maximum allowable stress of $60$MPa and the segment $BCD$ has a maximum allowable stress of $450$MPa.

Determine the minimum required diameter $($as a full $mm)$ for segments $AB$ and $BCD.$

Solution: