Reference problem ===================== 3D geometry ------------ The structure is a straight parallelepiped with a square base. The dimensions of the bar (see []) are: :math:`\mathit{LX}\mathrm{=}5m`, :math:`\mathit{LY}\mathrm{=}5m` and :math:`\mathit{LZ}\mathrm{=}25m`. The crack (or rather the interface) is introduced by level functions (level sets) directly into the command file using the DEFI_FISS_XFEM [:ref:`U4.82.08 `] operator. The interface is present in the middle of the structure through its representation by a level set :math:`\mathit{LSN}` (see []) equation: :math:`\mathrm{LSN}` (for the interface map): :math:`Z\mathrm{-}\frac{\mathit{LZ}}{2}` **Figure** 1.1-b .. image:: images/10000000000004BE000002BA79DCF7900B347925.png :width: 4.9055in :height: 2.8508in .. _RefImage_10000000000004BE000002BA79DCF7900B347925.png: **Figure** 1.1-a **: Bar geometry and interface position** 2D geometry ------------ The structure is a rectangle. The dimensions of the bar (see []) are: :math:`\mathrm{LX}=1m`, :math:`\mathrm{LY}=5m`. The interface is introduced by a level set function directly into the command file using the DEFI_FISS_XFEM [:ref:`U4.82.08 `] operator. The interface is present in the middle of the structure through its representation by a level set :math:`\mathrm{LSN}` (see []) equation: :math:`\mathrm{LSN}` (for the interface map): :math:`Y-\frac{\mathrm{LY}}{2}` .. image:: images/1000000000000154000000FA803A0DB55E2B3B0E.png :width: 3.5409in :height: 2.6043in .. _RefImage_1000000000000154000000FA803A0DB55E2B3B0E.png: **Figure** 1.2-a **: Plate geometry and interface position** Material properties ---------------------- Young's module: :math:`E\mathrm{=}205000\mathit{MPa}` Poisson's ratio: :math:`\nu \mathrm{=}0.3` Boundary conditions and loads ------------------------------------- The nodes on the lower face of the bar are embedded and a displacement is imposed on those on the upper face. Here we want to show the possibility of separating a finite element in two with X‑FEM.