An explicit application of partition of unity approach to XFEM approximation for precise reproduction of a priori knowledge of solution

SUMMARY: The application of the XFEM to fracture mechanics is effective, because a crack can be modeled independently from the meshes and a complex remeshing procedure can be avoided. However, the classical XFEM has an essential problem in the approximation of partially enriched elements, that is, blending elements, which causes a lack of accuracy. For the weighted XFEM, although the numerical results show the effective improvements, it was found that the issue of blending elements still remains upon detailed examination. In the present paper, the PU-XFEM is formulated as an explicit application of the partition of unity (PU) approach to the XFEM, in order to precisely reproduce a priori knowledge of the solution by enrichment. The PU-XFEM is applied to two-dimensional linear fracture mechanics, and its effectiveness is verified. It is consequently found out that the PU-XFEM precisely reproduces a priori knowledge of the solution and is therefore effective to completely solve the problem of the blending elements.