Problem $2$

The cold$-$drawn AISI $1040$ steel bar shown in the figure is subjected to the following loading conditions:

$($a$)$ Axial load fluctuating between $-20$ kN $($compression$)$ to $20$ kN $($tension$).$

$($b$)$ Axial load fluctuating between $10$ kN $($tension$)$ to $20$ kN $($tension$).$

For each case, estimate the fatigue factor of safety based on achieving infinite life. Also check the yielding factor of safety. If infinite life is not predicted, estimate the number of cycles to failure.

ANSWER:$($a$)$ Se$=190\mathrm{.}91$ MPa $,$ nf$=0\mathrm{.}84,$ N $=293570$ cycles b$)$ nf $=1\mathrm{.}7,$ Infinite fatigue life$)$