In the presence of **materi_damage** ,
the **materi_stress** follows:

For the damage, the **group_materi_damage_mazars** model is available:

where

and

Here
contains the positive principal strains.
The parameter is given by the ratio
,
where contains the total strains (both negative and positive).
The parameter is the strain threshold for damage;
other material parameters are
.
Typically for concrete:

You can combine damage freely with plasticity models or other material behavior.

tochnog 2001-09-02