A direct evaluation of stress intensity factors using the Extended Dual Boundary Element Method

We introduce an alternative method in computational fracture mechanics to evaluate Stress Intensity Factors (SIFs) directly using the Extended Dual Boundary Element Method (XBEM) for 2D problems. Like other enrichment approaches, the new approach is able to yield accurate results on coarse discretisations, and the enrichment increases the problem size by only two degrees of freedom per crack tip. The BEM equations formed by collocation at nodes are augmented by two additional equations that enforce continuity of displacement at the crack tip. The enrichment approach provides the values of SIFs KI and KII directly in the solution vector and without any need for postprocessing such as the J-integral. Numerical examples are used to compare the accuracy of these directly computed SIFs to J-integral processing of both conventional and enriched boundary element approximations.