A recovery-type error estimator for the extended finite element method based on singular plus smooth stress field splitting

A new stress recovery procedure that provides accurate estimations of the discretization error for linear elastic fracture mechanic problems analyzed with the extended finite element method (XFEM) is presented. The procedure is an adaptation of the superconvergent patch recovery (SPR) technique for the XFEM framework. It is based oil three fundamental aspects: (a) the use of a singular+smooth stress field decomposition technique involving the use of different recovery methods (or each field: standard SPR for the smooth field and reconstruction of the recovered singular field using the stress intensity factor K for the singular field: (b) direct calculation of smoothed stresses at integation points using conjoint polynomial enhancement and (c) assembly of patches with elements intersected by the crack using different stress interpolation polynomials at each side of the crack. The method was validated by testing it oil problems with an exact solution in mode I, mode II, and mixed mode and oil it problem without analytical solution. The results obtained showed the accuracy of the proposed error estimator. Copyright (c) 2008 John Wiley & Sons. Ltd.