R$2\mathrm{.}4$:

The stepped shaft shown in Fig R$2\mathrm{.}4$ rotates at $450$ rpm $.$

If the $\backslash ($ r$=12\backslash$mathrm$\{$~mm$\}\backslash ),$ determine the largest power that can be transmitted without

Fig. R$2\mathrm{.}4$: Stress concentration in circular shaft with fillets under torsion. sharing stress of $50$ MPa $.$