  This paper presents the first time implementation of the eXtended Finite
Element Method (XFEM) in the general purpose commercial software COMSOL
Multiphysics. An enrichment strategy is proposed, consistent with the structure
of the software. To this end, for each set of enrichment functions, an
additional Solid Mechanics module is incorporated into the numerical framework,
coupled with compatible modifications to the internal variables. The Linear
Elastic Fracture Mechanics (LEFM) is exclusively adopted for the crack
analysis. The model pre-processing, level set update, stress intensity factor
calculation and crack propagation analysis are conducted by employing COMSOL's
built-in features in conjunction with external MATLAB functions through COMSOL
LiveLink. All implementational aspects and suggested remedies for the treatment
of enriched elements, framework setup, evaluation of stress intensity factors,
and numerical integration are described in detail. The accuracy and robustness
of the proposed method are examined by several numerical examples for
stationary and propagating crack problems in 2D and 3D settings. The results
represent excellent agreement with available analytical, numerical and
experimental observations in the literature.
  Keywords:XFEM; COMSOL Multiphysics; Crack analysis; Fracture propagation
