Features and validation ============================= Tips for using settings -------------------------------------------- In summary, for the search for the **crack path** the necessary parameters are: * :math:`{l}_{\mathrm{orth}}` (LONG_ORTH) * :math:`{l}_{\mathrm{reg}}` (LONG_REG) * :math:`a` (PAS) * :math:`{N}_{\mathit{orth}}` (NB_POINT) * BORNE_MIN to be entered under the keyword factor RECHERCHE. The recommended range of use is as follows: * :math:`{l}_{\mathit{orth}}` must be greater than or equal to the width of the damaged band; good results are already obtained by adopting twice this width; * :math:`{l}_{\mathrm{reg}}` may be in the interval :math:`0.5\Delta \le {l}_{\mathit{reg}}\le 2\Delta`, :math:`\Delta` being the size of the finite elements in the damaged areas (compromise between sufficient smoothing and the risk of losing too much information from the unsmoothed damage profile); * :math:`a` depends on the curvature of the path and how many points the user wants to describe the crack, as an indication it can also be taken in an interval :math:`0.5\Delta \le a\le 2\Delta`; * the choice of :math:`{N}_{\mathrm{orth}}` must guarantee at least 10 points per finite element; * BORNE_MIN is the value of the field for which the search is stopped in one direction; in the case of damage, values :math:`>0.5` are taken to be sure that the crack is well formed. For the calculation of the crack opening, the parameter BORNE_MAX must be less than 0.8, if field :math:`X` is the damage. Validation ---------- The order is validated by the zzzz264 test case [:external:ref:`V1.01.264 `]. In modeling A, a crack path is sought and compared with an analytical path. In B, C modeling, we look for the crack path and the opening on a mechanical result, obtained using *Code_Aster* damage laws.