Boundary element crack closure calculation of axisymmetric stress intensity factors

The boundary element method is useful for accurate calculation of stresses and displacements in axisymmetric elasticity. However, the accurate evaluation of singular quantities such as crack tip stress intensity factors requires either a special singular element or a large number of conventional elements. Here the modified crack closure integral is combined with conventional quadratic boundary elements to accurately calculate stress intensity factors. The robustness of this approach is shown through a convergence study and illustrated through several examples including a circumferential crack in a round bar, a cylindrical crack, and a circumferential crack emanating from a spherical cavity. It is concluded that the present approach leads to accurate stress intensity factors even for coarse meshes.