Contour integral approaches for the evaluation of stress intensity factors using displacement discontinuity method

The stress intensity factors (SIFs) are of great importance for the determination of stress and displacement fields near crack tip and the prediction about crack propagations. In the context of linear elastic fracture mechanics (LEFM), this paper proposes contour integral approaches to calculate SIFs for two-dimensional cracks. The proposed approaches are derived from the conservative J- and I-integrals, in which constant elements of the displacement discontinuity method (DDM) are employed. Two numerical examples, a horizontal straight crack and a slanted straight crack under uniaxial tension at infinity, are conducted to demonstrate the validation of the approaches. Numerical results confirm that highly accurate SIFs can be extracted by integral contours remote from crack tip and increasing the total number of DDM elements can improve accuracy significantly.