Is it possible to change a material modulus over different stages?

The modulus can be changed both at failure (to a residual modulus) and from stage to stage (hardening or softening).  See the Material Properties>Staged Material Properties dialog for more information.  Note that you should not drop the modulus to zero in finite element analyses, as this will cause numerical issues.

Phase2-stagedpropertiesdialog.PNG

Material properties can be staged in the Staged Material Properties dialog box