Comparison of Ductile Damage Models
The prediction of damage with finite element modelling of thermo-mechanical
processes is of main interest for manufactured part optimisation. Several existing plasticity
damage theories are intended for the prediction of the growth of voids. Since the early work
of Gurson [GUR 77] improved by Tvergaard [TVE 81] and Oudin et al. [OUD 95],
constitutive dilatational plastic equations have been proposed by Gelin [GEL 95] and Boyer
[BOY 97, BOY 99]. From these dissipation potentials, dilatational plastic stress-strain laws
have been discussed and implemented in proprietary finite element software for modelling of
axisymmetric bulk forming processes. In the present work, numerical comparison of these
ductile damage theories are presented for the collar test and an industrial workability test.
The influence of the mean stress and of the deviatoric stress tensor on the void volume
fraction rate are analysed. The cases of empty voids and voids with a free inclusion are
considered. The sensitiveness of the ductile damage to shear stress is shown with the radii
changes of an initial spherical void.
Cyril BORDREUIL, Emmanuelle VIDAL-SALLÉ, Jean-Claude BOYER
Reçu le 26 juillet 2001.
Accepté le 24 octobre 2001.
Metal forming, damage, void growth.