What is the largest size mm external crack that a thick plat

What is the largest size (mm) external crack that a thick plate of aluminum alloy 7075-1651 can support at an applied stress of a) 0.8 of the yield strength? Assume Y-1 From Table 7.1 of the book. 7075-1651, K_IC = 24.2 MPa Squareroot m and sigma_vs = 495 MPa K_IC = Y sigma_f Squareroot pi a

Solution

Stress intensity factor K defines the severity of a cracked surface and failure will occur when K = K_IC.

Yield strength of the material, sYS = 495 [MPa]

Applied stress, sF = 0.8 * sYS = 396 [MPa]

Given: Y = geometry correction factor = 1

For a thick plate (plane stress) loading:

Critical crack size = a = (1/p) * (K_IC/Y/ sF)² = (1/p) * (24.2 MPa-m^0.5/1/396 [MPa])² = 1.19E-3 [m] = 1.19 [mm]