The characterisation of the stress fields in proximity of crack tips is a fundamental task in fracture mechanics, providing means for the assessment of the fracture resistance or the crack growth rate. Among several methods available for the computation of the crack-tip stress intensity factor, an extremely efficient and flexible solution strategy is obtained using the distributed dislocation technique. This method has been successfully applied to several remote loading conditions and cracked geometries and can also take into account the effect of surface friction and roughness through the inclusion of an appropriate interface model. In this paper, we make use of a non-linear algorithm, which uses dislocations distributed along the crack, to compute the crack-tip stress intensity factors under remote mixed-mode stress fields. It is shown that the algorithm can be effectively applied to different geometries, notably to cases where the mode mixity originates from geometrical features, such as in the presence of notches or re-entrant corners. In particular, the effect of dilatancy is correctly captured with the adopted method, and its consequences are discussed with regard to the onset of unstable crack propagation under monotonic loading.
Near-tip stress fields of rough and frictional cracks under mixed-mode loading / Spagnoli, A.; Carpinteri, A.; Terzano, M.. - In: FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES. - ISSN 1460-2695. - 41:(2018), pp. 2099-2109. [10.1111/ffe.12765]