The imposition of Dirichlet boundary conditions in a non conformal mesh can be done with the use of Lagrange multipliers. But this leads to an over-constrained problem that produces an unstable solution if the finite element subspace for the Lagrange multipliers field does not satisfy the inf-sup condition. A stabilization technique is presented, with on a parameter depending on the mesh size. A benchmark is resolved to validate the stability of our method.
Bricteux, G. (2011). Imposing Dirichlet boundary conditions in the eXtended Finite Element Method. Fifth International Conference on Advanced COmputationalMethods in ENgineering, Liège. https://hdl.handle.net/2078.5/39036