Introduction
=============




Choosing the type of law of behavior
------------------------------------

The choice of the law of behavior is of course a function of the material that is being modelled, but also of the phenomena to be treated: for example, the same steel will be elasto-plastic at low temperature, and visco-plastic at high temperature.

This document gives ways to make good use of elasto- (visco) -plastic behaviors (mainly for metals).

For other types of behavior, reading the following documents is recommended:


* For laws with damage (case of concrete for example), see
    :ref:`u2.05.06`
    :ref:`u2.05.06`


* For metallurgy, see
    :ref:`u2.03.04`


* For porous media in THM, see
    :ref:`u2.04.05` and
    :ref:`r7.01.11`


* For the use of CZM elements, see
    :ref:`u2.05.07`
    :ref:`u2.05.07`


* For specific laws of discrete elements, see
    :ref:`r5.03.17`


* For laws specific to 1D elements, see
    :ref:`r5.03.09`


* For hyperelastic laws (Mooney-Rivlin type) see
    :ref:`r5.03.19`


* For laws of behavior specific to fuel rods and metals under irradiation, see
    :ref:`r5.03.08` and
    :ref:`r5.03.23`


* For the laws of crystalline plasticity, see
    :ref:`r5.03.11`
    :ref:`r5.03.11`




Which elasto-plastic laws to choose: what are their capacities?
--------------------------------------------------------

In this document, elements are provided for choosing laws of behavior, according to their capacities, and the phenomena to be modelled.

Advice for the identification of parameters will be given, with emphasis on the field of validity of the models: the parameters are identified for very specific deformations, speeds, temperatures, which must correspond to the studies envisaged.

On the other hand, if the models envisaged require it, it may be necessary to conduct the identifications in the field of large deformations. For this purpose, adapted formalities can be used:


* SIMO_MIEHE for Von Mises behaviors with isotropic work hardening, laws with the effect of metallurgical phases, Rousselier's law,


* GDEF_LOG for most behaviors,


* GROT_GDEP for hyperelastic laws of the MOONEY - RIVLIN type.