INFLUENCE OF THE CRACK TIP THREE-DIMENSIONALITY ON THE EVALUATION OF SIFs BY CAUSTICS

摘要

The extent of the three-dimensional region surrounding the tip of an opening-mode crack is studied experimentally by the optical method of caustics. It is shown that the state of stress changes from plane strain at the tip to plane stress at a critical distance from the tip. For the correct evaluation of stress intensity factors (SIFs) the generatrix curve of the caustic should lie in the region where the state of stress is plane stress. Use of optically anisotropic materials to compensate for the three-dimensional effect in the determination of SIFs is proposed.