Example $6-2$

Given a $1050$ HR steel, estimate

$($a$)$ the rotating$-$beam endurance limit at ${10}^6$ cycles.

$($b$)$ the endurance strength of a polished rotating$-$beam specimen corresponding to ${10}^4$ cycles to failure

$($c$)$ the expected life of a polished rotating$-$beam specimen under a completely reversed stress of $385$ MPa $.$