Practical aspects of use
===============================

This resolution method is activated by specifying, under the simple keyword METHODE of the STAT_NON_LINE operator, METHODE = 'IMPLEX' and by specifying the law of behavior used under COMPORTEMENT.

Only certain laws of behavior are currently available with the IMPLEX method. Table 2 summarizes the laws of behavior available according to the type of elements considered.


.. csv-table::

    "**Surface or volume elements**", "**Bar elements**", "**Membrane elements and membrane_grid**"
    "ELAS "," ELAS "," ELAS"
    "VMIS_ISOT_LINE "," VMIS_ISOT_LINE ", ""
    "ENDO_ISOT_BETON ", "", ""
    "ENDO_FRAGILE ", "", ""


 **TABLEAU 2: laws of behavior available with the method** IMPLEX

For each law of behavior, the last internal variable is modified and corresponding in this case to the :math:`\frac{\Delta \alpha }{\Delta t}` ratio.

The method requires the matrix to be updated at each increment (REAC_INCR = 1) and only one iteration. The equilibrium residue is calculated, but no criteria are associated with it. We will be able to notice a possible major error by seeing that the relative residue is high.

For more information on practical aspects, refer to [:ref:`6 <6>`] and [:ref:`7 <7>`]. Method IMPLEX is illustrated through the SSNP140 [:ref:`8 <8>`] and SSLS132 test case.