Mode-I stress intensity factors for cracked special-shaped shells under bending

The slender special-shaped shells possess both shell and beam characteristics, which are widely used in practical engineering. A slender special-shaped shell under bending with some complex cracks, such as a frost flower-shaped crack and circumferential periodic cracks in a pipeline, is actually a typical three-dimensional complex crack problem with many different singular stress fields and stress intensity factors. In the present article, a very simple and practical technique based on the elementary mechanics and the concept of the conservation law is proposed to determine the stress intensity factors. The results from present method are shown to agree well with available solutions and FEM. In particular, the present method can also be easily applied to the other similar cracked structural shells.