3. Implementation in Code_Aster

3.1. Internal variables

A number of model « internal variables » in the sense of Code_Aster are created and stored. The plastic deformation tensor \({\varepsilon }^{p}\) is not stored because it is obtained by post-treatment calculation from the total stresses and deformations. The values of the internal variables at the Gauss points (VARI_ELGA) are for all models:

The VARI_34 status indicator for active mechanisms after convergence is a byte (8 digits) obtained by binary system. Each digit is associated with a plastic mechanism, by assigning the value 1 for an active mechanism and the value 0 for an unsolicited mechanism.

This makes it easy to visualize the active mechanisms with a simple scalar. For example, if VARI_34 = 10000010, then the active criteria are: deviatory \(\mathrm{XZ}\) monotonic (\({10}^{1}\)) and isotropic cyclic (\({10}^{7}\)).