Let the bar in Fig. $2\mathrm{.}7-1$ be loaded until all material across $AB$ is plastic. If all load is then removed, and unloading is elastic, what is the residual stress at $B,$ in terms of $K_t$ and ${}_Y?$

$($a$)$

$($b$)$

$($c$)$

FIGURE $2\mathrm{.}7-1($a$)$ Stress distribution in a plate with a circular hole. $($b$)$ Idealized stressstrain relation. $($c$)$ Approximate stress distributions for linearly elastic and fully plastic conditions.