The damage evolution law describes the rate of degradation of the material
stiffness once the corresponding initiation criterion has been reached. For
damage in ductile metals
Abaqus
assumes that the degradation of the stiffness associated with each active
failure mechanism can be modeled using a scalar damage variable,
${d}_{i}$
($i\in {N}_{\mathrm{act}}$),
where ${N}_{\mathrm{act}}$
represents the set of active mechanisms. At any given time during the analysis
the stress tensor in the material is given by the scalar damage equation

$$\mathit{\sigma}=\left(1-D\right)\overline{\mathit{\sigma}},$$

where D is the overall damage variable and
$\overline{\mathit{\sigma}}$
is the effective (or undamaged) stress tensor computed in the current
increment. $\overline{\mathit{\sigma}}$
are the stresses that would exist in the material in the absence of damage. The
material has lost its load-carrying capacity when $D=1$.
By default, an element is removed from the mesh if all of the section points at
any one integration location have lost their load-carrying capacity.

The overall damage variable, D, captures the combined
effect of all active mechanisms and is computed in terms of the individual
damage variables, ${d}_{i}$,
according to a user-specified rule.

Abaqus
supports different models of damage evolution in ductile metals and provides
controls associated with element deletion due to material failure, as described
in
Damage evolution and element removal for ductile metals.
All of the available models use a formulation intended to alleviate the strong
mesh dependency of the results that can arise from strain localization effects
during progressive damage.

Abaqus/CAE Usage

Property module:
material editor: :