Adapted from problem $8\mathrm{.}8(25$ marks$)$ A structural component is fabricated from an alloy that has a plane strain fracture toughness of $45MPA{m}^{\frac{1}{2}}.$ It has been determined that this component fails at a stress of $300$ MPa when the maximum length of a surface crack is $0\mathrm{.}95$ mm $.$ What is the maximum allowable surface crack length $($in mm$)$ without fracture for this same component exposed to a stress of $300$ MPa and made from another alloy with a plane strain fracture toughness of $57\mathrm{.}5MPA{m}^{\frac{1}{2}}?$