4. 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.

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 \(\frac{\Delta \alpha }{\Delta t}\) 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 [6] and [7]. Method IMPLEX is illustrated through the SSNP140 [8] and SSLS132 test case.