(1) A microalloyed steel, quenched and tempered at 250C, has a yield strength (y) of 1,750 MPa and a plane-strain fracture toughness KIcof 43.50 MPa m1/2. What is the largest disk-type inclusion, oriented most unfavorably, that can be tolerated in this steel at an applied stress of 0.5y?

(2) Consider a maraging steel plate of thickness (B) 3 mm. Two specimens of width (W) equal to 50 mm and 5 mm were taken out of this plate. What is the largest through-the-thickness crack that can be tolerated in the two cases at an applied stress of =0.6y, wherey(yield stress)= 2.5 GPa? The plane-strain fracture toughnessKIcof the steel is 70 MPa m1/2. What are the critical dimensions in the case of a single-edge notch specimen?

(3) Engineers are designing a ceramic component for a jet engine. The ceramic has a fracture toughness of 8 MPa m1/2. The ceramic is subjected to a maximum tensile stress of 500 MPa. Calculate the maximum size of surface flaws that the part can have

(4) A cylindrical pressure vessel (length of 10 m; diameter of 1 m) is made from a high strength steel withKIc=100 MPA m1/2 and a yield strength of 1,600 MPa. The thickness of the vessel is 25 mm. NDE has revealed a longitudinal crack penetrating 7 mm into the cylinder wall.

(a)What maximum pressure can the cylinder be loaded to?

(b)What is the percentage reduction in maximum pressure due to the presence of flaw?