Imposing essential boundary conditions in the eXtended Finite Element Method

This paper is devoted to the imposition of Dirichlet type conditions within the eXtended Finite Element Method. The X-FEM method allows one to easily model surfaces of discontinuity or domain boundaries on a mesh not necessarily conforming to these surfaces. Imposing Neumann type boundary condition on boundaries running through the elements is straightforward. It is not the case for Dirichlet type boundary conditions (or the limiting case of stiff boundary conditions). In this paper, we show that the strong imposition of Dirichlet conditions inside elements leads to locking and suggest a remedy.