.. _R5.03.24:

**r5.03.24** Large deformation model GDEF_LOG
====================================================

**Summary:**

This paper presents a hypoelastic formulation of large deformations for von Mises-type laws of behavior called GDEF_LOG in Code_Aster.

This model, due to C.Miehe, N.Apel and M.Lambrecht [:ref:`13 <13>`] is a model of large deformations based on a logarithmic measurement, with a particular duality stress tensor. It is valid regardless of the behavior in small deformations and has the advantage of providing a symmetric tangent matrix. No modification of kinematic internal variables is necessary. It allows for an incrementally objective integration of laws of behavior (like model SIMO_MIEHE). However, like all hypoelastic laws, the laws of behavior are, from a decreasing point of view, limited to slight elastic deformations.

This document illustrates the capabilities of this model and the advantages compared to approximation PETIT_REAC.




.. toctree::
    :hidden:

    self

.. toctree::
    :maxdepth: 2
    :numbered:

    Introduction
    _criture_et_hypoth_ses
    Algorithme_
    Validit__des_mod_les_de_grandes_d_formations
    Comparaison_avec_PETIT_REAC
    Bibliographie
    Description_des_versions_du_document
    Annexe_1___Calcul_des_d_formations_logarithmiques