A rectangular bar is cut from an AISI $1020$ cold$-$

drawn steel flat. The bar is $2\mathrm{.}5$ in wide by $\frac{3}{8}$ in thick

and has $a^{\frac{1}{2}}$ in diameter hole drilled through the center

as shown. The bar is loaded in push$-$pull fashion by

axial force $F,$ producing fully reversed stress. Using a

design factor of $2,$ estimate the largest force $F$ that can be applied for an infinite life design.

Ignore buckling.

HINT: As with many fatigue failure problems, to solve this, it will be necessary to find

a$.$ the unmodified endurance strength, $S_s^{\text{'}}$

b$.$ the Marin factors $($assume any for which information is not given to be $1)$ and the fully$-$

modified endurance strength $S_{}$

c$.$ the theoretical and fatigue stress concentration factors

d$.$ the amplitude and midrange stresses, ${}_a$ and ${}_m$

e$.$ which infinite life theory to use, though this will be simplified because of ${}_m$