The plate with a circular hole in the following figure is subjected to a tensile stress of σ0 at the boundaries AB and CD. The plate is made of steel 4340 material with Sy = 1515 MPa, if b = 200 mm, a = 50 mm, and the plate thickness, t = 20 mm, determine the maximum value of σ0 that can be safety applied considering a safety factor of 1.5.
Perform another analysis to calculate the maximum value of σ0 assuming two edge cracks of 2 mm each at points E and F of the hole, in directions perpendicular to the loading direction. What is the percentage of reduction of the allowable stress (σ0) if cracks are present?