Extent of surface regions near corner points of notched cracked bodies subjected to mode-I loading

In the present paper, the extent of surface regions in cracked bodies subjected to mode-I loading was examined, which is important for a proper definition of finite element meshes. Different specimen geometries with and without lateral notches, representative of several engineering situations, were selected. Realistic crack shapes were considered in this analysis by employing a 3D-FE automatic crack growth technique. A triaxiality parameter (h) was calculated for different loading and geometrical parameters, namely thickness, crack length, crack shape and particularly radius of lateral notches. Criteria were defined to objectively define the extent of surface and near surface regions, S1 and S2, respectively (slope of h>0.9 for S1 and 0.1<slope of h<0.9 for S2). It was observed that the extent of surface region (S1) is one order of magnitude higher than the extent of the near surface region (S2). For unstable crack shapes, S1 and S2 are smaller than for stable shapes, but within the same order of magnitude. The extent of both regions was related with the elastic stress concentration factor of the corresponding uncracked geometries and a linear relationship was found. Finally, equations that account S1 and S2 through the stress concentration factor, notch radius, specimenʹs size and crack length were proposed.