Description: Abaqus offers two different ways to evaluate the contour integral. The first is based on the conventional finite element method. It typically requires the user to conform the mesh to the cracked geometry, to explicitly define the crack front, and to specify the virtual crack extension direction. Detailed focused meshes are generally involved. Such an approach is quite cumbersome to obtain accurate contour integral results for a three-dimensional curved surface crack. The extended finite element method (XFEM) alleviates these shortcomings. XFEM does not require the mesh to match the cracked geometry. The presence of a crack is ensured by the special enriched functions in conjunction with additional degrees of freedom. Such an approach also removes the requirements of explicitly defining the crack front and specifying the virtual crack extension direction when evaluating the contour integral. The data required for the contour integral are determined automatically based on the level set signed distance functions at the nodes in an element.