Development of stress intensity factor equations for rectangular shaped surface flaws in a plate

Finite element computations and development of equations of stress intensity factors for rectangular shaped surface flaws in a plate are presented. Rectangular surface flaws rather than semi-elliptic shapes are assumed here because of the typical features of the stress corrosion crackings (SCCs) that have recently been found at welded joints in nuclear reactor structures: the SCCs are confined in the weld metal and their aspect ratios are large. The assumption of rectangular shaped flaws simplifies modeling especially for those with very large aspect ratios. A way is presented to define the stress intensity factors at the deepest and surface points of the flaws using the J-integral method. Then stress intensity factor equations are developed for a plate subject to stresses that are expressed by polynomial functions of distance from the plate surface.