4. Summary of results

The results are satisfactory and validate the interface between Code_Aster and UMAT in small deformations.

• the results are valid when the physical unit of the problem changes (\(\mathrm{Pa}\) in \(\mathrm{Mpa}\)), or following a rotation or symmetry of the load

• the results converge correctly with the time step, and the integration schemes are robust, since they allow large time steps to be used. However, for these models using viscosity, it should be noted that they are more sensitive to the time step than for elasto-plastic models.

• the tangent matrices are correct because they are similar to the tangent matrices calculated by disturbance.