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Marks Question 3 (20 Marks Total) A defect assessment is to be carried out on a steel component. The steel has yield strength o, = 550 MPa, Young's modulus E = 210 GPa, Poisson's ratio, v=0.3 and fracture toughness Je = 0.15 MPa m. A Ramberg-Osgood material law has been fitted to the tensile behaviour of the material, m o e() E o = - + c Ey Oy with n = 7, a = 1 and 5 = 2.6 x 10. Following an inspection an embedded defect of size 2a = 2.50 cm has been detected in the component. The cross sectional area of the component (2W x B) is 0.2 m x 0.05 m and the tensile load P is 4.5 MN. The assessment is to be carried out using the GE-EPRI scheme. (a) Determine the value of Kg and the corresponding... value to be used in the GE-EPRI J estimation scheme using the plane stress plastic zone correction. The K solution for a centre crack under tension is: 10 P K= F(a/W) = Fla/W); 1 πα πα 4W B/W cos zw 10 (b) Evaluate the total and determine if the defect is safe. The plane strain limit load for the geometry is P. = 2.30984W -a). Using the h calibration functions in Table 03, the corresponding., equation is: 7+1 Jp =< £90,0(1-0). P n=1 R=3 = 7 Plane strain 2.80 4.06 n=5 4.35 4.47 4.33 1 8 a/W Plane stress 2.80 4.01 4.65 2a 3.29 a/W = #1 1 4 3.18 3.11 3.20 Plane strain 2.54 Plane stress 2.54 Plane strain 2.34 Plane stress 2.34 3.21 3.14 2.65 2.52 3 2.51 لا | 2W a/W 2.25 2.17 2.35 Table Q3 GE-EPRI h-functions for a centre cracked panel Page 4 of 5