Current Attempt in Progress

A specimen of a $4340$ steel alloy with a plane strain fracture toughness of is exposed to a stress of $2075$ MPa $(301000$ psi$).$ Assume that the parameter Y has a value of $1\mathrm{.}11.$

$($a$)$ If the largest surface crack is $)$ long, determine the critical stress ${}_c$

MPa

$($b$)$ Will this specimen experience fracture?