3. Operands#

3.1. Operand MODELE_IN#

♦ MODELE_IN = mo

mo: name of the initial model (also called « healthy model ») built on the mesh that was used to define the crack beforehand by the operator DEFI_FISS_XFEM [U4.82.08].

This initial model, built with the AFFE_MODELE [U4.41.01] operator, is the basis for creating the new model. It is necessary to choose a different name for the new template, editing an existing template is not allowed, the check is performed during the syntactic analysis of the command file.

3.2. Operand FISSURE#

♦/FISSURE = (fiss1,...)

(fiss1,…): list of the names of the cracks defined beforehand by the operator DEFI_FISS_XFEM [U4.82.08]. The number of cracks in a model is not limited.

3.3. Operand MODELE_THER#

/MODELE_THER = modxth

The use of this keyword is only useful in the particular case of thermo-mechanical chained calculations with X- FEM. In this case, the following checks will be carried out by the operator:

  • modxth must be the thermal model X- FEM (already produced by the operator MODI_MODELE_XFEM, with the keyword FISSURE) with which the linear thermal problem is solved by the operator THER_LINEAIRE [U4.54.01];

  • the healthy mo model must be a mechanical model, and must have been defined on the same mesh as the enriched thermal model modxth

The model produced by the operator is a mechanical model.

3.4. Operand CRITERE#

♦ CRITERE = write

crit: real value of the criterion allowing the cancellation of enriched degrees of freedom when the crack passes near a node. When the crack cuts a 3D element into two volumes, the ratio between the smallest volume and the largest volume should not exceed this criterion, otherwise, it may cause conditioning problems in the stiffness matrix, and lead to zero pivots. Thus, if the criterion is exceeded, the degrees of freedom that may lead to zero pivots are automatically eliminated. The default value for the criterion is based on simple tests [R7.02.12].

3.5. Operand CONTACT#

♦ CONTACT =/'SANS'

/'STANDARD'

/'MORTAR'

This operand makes it possible to signal if interface forces exist between the lips of the crack: they can be contact, or cohesive forces.

If this is the case, a contact load or cohesive forces must then be introduced by the DEFI_CONTACT command. For all formulations, the value STANDARDqui must be entered, except for the cohesive law CZM_LIN_MIX, which is a mixed cohesive law adapted to linear elements (see R5.03.55]), for which the value MORTAR is entered. Indeed, the latter requires the addition of several multiplier fields, which must therefore be filled in when modifying the model in order to create the appropriate elements.

3.6. Operand PRETRAITEMENT#

♦ PRETRAITEMENT S =/'AUTO'

/'SANS'

/'FORCE'

This operand makes it possible to indicate whether the algebraic preconditioning algorithms should be activated (modification of the stiffness matrix). By default, the choice is automatic (“AUTO”). You can either deactivate them (“SANS”) or force them (“FORCE”).

Note: if there are quadratic elements in the model, the pre-conditioning algorithms will be activated.

3.7. Operand DECOUPE_FACETTE#

♦ DECOUPE_FACETTE =/'DEFAUT'

/'SOUS_ELEMENTS'

This operand makes it possible to activate an alternative method (“SOUS_ELEMENTS”) for constructing contact facets than the one by default (“DEFAUT”).

The alternative method makes it possible in particular to treat the case of quadratic facets.

3.8. Operand INFO#

/    1    :
print on the file “MESSAGE” #.

# calculation steps. Of the number of finite elements in model

 
/    2    :

same printing + printing for each mesh of the enriched mesh type and its finite element type number.