Fitness-for-Service Analysis of the Interplay Between a Quarter-Circle Corner Crack and a Parallel Semi-Elliptical Surface Crack in a Semi-Infinite Solid Subjected to In-Plane Bending: Part I—The Effect on the Quarter-Circle Corner Crack

For the purpose of Fitness-For-Service analysis, the effect of a semi-elliptical surface crack on a parallel quarter-circle corner crack in a semi-infinite solid subjected to pure bending is studied using 3D finite element analyses. While keeping the geometry of the quarter-circle corner crack constant, the SIF distributions along its front are studied for various geometrical configurations of the semi-elliptical surface crack and several crack layouts. The problem is solved for a wide range of parameters, e.g., the ellipticity of the semi-elliptical b1/a1 = 0.1~1; the relative crack size of the two parallel cracks a1/a2 = 1/3~2; the normalized vertical and horizontal gaps between the two cracks, H/a2 = 0.4 and 1.2, and S/a2 = −0.5 and 1, respectively. The results indicate that the semi-elliptical surface crack might have a considerable effect on the SIF distribution along the quarter-circle corner crack both in amplifying and reducing the SIF. These effects are highly dependent on the semi-elliptical surface crack geometry and the cracks’ configuration. It is further concluded that it is necessary to perform a full 3D analysis, similar to the present one, in order to quantify the “real” effect of neighbouring cracks, in view of the existing inadequate fitness for service criteria.