On the explicit evaluation of stress intensity factors in the hybrid boundary element method

ABSTRACT The hybrid boundary element method, as based on the Hellinger‐Reissner potential for assumed singular stress fields, is suited for the explicit mathematical description of high gradients. In this paper, after an introductory overview of the method and an account of different attempts of application to fracture mechanics problems, one makes use of Westergaard complex functions for numerically handling general curved cracks, in which the exact gradient of the stress field at crack tip is considered, for any planar configurations. Modes I and II stress intensity factors are directly obtained as the primary unknowns of the problem, which eliminates the necessity of post‐processing results. Fairly good accuracy is achieved at low computational costs, as numerically assessed by means of several examples. The formulation seems to present no restrictions, for cases of both single and multiple internal cracks. At present, an extension to generally curved edge cracks as well as to kinked cracks is being investigated, as the method relies on the existence of analytical functions for the explicit description of local stress fields.