The damage evolution definition defines how the material degrades after one
or more damage initiation criteria are met.
Multiple forms of damage
evolution might act on a material at the same time—one for each damage initiation criterion
that was defined.
The procedure below includes data entries for every type of damage evolution
available in the Property module. The selections vary with the current damage initiation form.
When you create a damage initiation criterion in the Edit
Material dialog box, select SuboptionsDamage Evolution to specify the associated damage evolution parameters.
(For information on entering damage initiation criteria, see Defining damage.)
Select the Type of damage evolution:
Displacement
Displacement damage evolution defines damage as a function of the
total (for elastic materials in cohesive elements) or the
plastic (for bulk elastic-plastic materials) displacement after
damage initiation. This type corresponds to the
Displacement at Failure field in the
Data table.
Energy
Energy damage evolution defines damage in terms of the energy
required for failure (fracture energy) after the initiation of
damage. This type corresponds to the Fracture
Energy field in the Data
table.
Select the Softening method:
Linear
Linear softening specifies a linear softening stress-strain
response for linear elastic materials or a linear evolution of
the damage variable with deformation for elastic-plastic
materials. Linear softening is the default method.
Exponential
Exponential softening specifies an exponential softening
stress-strain response for linear elastic materials or an
exponential evolution of the damage variable with deformation
for elastic-plastic materials.
Tabular
Tabular softening specifies the evolution of the damage variable
with deformation in tabular form and is available only when you
select Displacement for the type. The
Displacement at Failure field in the
Data table is replaced by a
Damage Variable field and a
Displacement field, and you can add
additional rows to define the displacements.
Select the Mixed mode behavior (for materials associated
with cohesive elements only):
Mode-Independent
Mode-independent is the default selection.
Tabular
Tabular mixed mode behavior specifies the fracture energy or
displacement (total or plastic) directly as a function of the
shear-normal mode mix for cohesive elements. This method must be
used when you select the Displacement type
with cohesive elements.
Power Law
Power law mixed mode behavior specifies the fracture energy as a
function of the mode mix by means of a power law mixed mode
fracture criterion; it is available only when you select the
Energy type with cohesive elements. The
Fracture Energy field in the
Data table is replaced by fracture
energy in the normal mode and first direction and second
direction shear mode components.
BK
The BK mixed mode behavior
specifies the fracture energy as a function of the mode mix by
means of the Benzeggagh-Kenane mixed mode fracture criterion.
The Data table entries are the same as
those for the Power Law.
Select the Degradation to determine how Abaqus combines damage evolution when multiple forms are active:
Maximum
The maximum degradation form indicates that the current damage
evolution mechanism will interact with other damage evolution
mechanisms in a maximum sense to determine the total damage from
multiple mechanisms. Maximum is the default selection.
Multiplicative
The multiplicative degradation form indicates that the current
damage evolution mechanism will interact in a multiplicative
manner with other damage evolution mechanisms defined using this
form to determine the total damage from multiple mechanisms.
Other damage evolution mechanisms defined using the maximum
degradation will interact with the combination of those using
the multiplicative form.
Select the Mode Mix Ratio to use in conjunction with the
Mixed mode behavior definition (for cohesive
elements):
Energy
The energy mixed mode ratio defines the mode mix in terms of a
ratio of fracture energy in the different modes. This definition
is the default, and it must be used when you select
Power Law or
BK
for the Mixed mode behavior.
Traction
The traction mixed mode ratio defines the mode mix in terms of a
ratio of traction components.
When you select Power Law or
BK for the
Mixed mode behavior for cohesive elements, toggle on
Power and enter the exponent in the power law or the
Benzeggagh-Kenane criterion that defines the variation of fracture energy with
mode mix for cohesive elements.
For the Hashin damage evolution model, the Data table
contains the following fields:
To define the damage evolution data that depend on the effective rate of
separation, toggle on Use rate-dependent data.
A column labeled rate-dependent appears in the
Data table.
To define damage evolution data that depend on temperature, toggle on
Use temperature-dependent data.
A column labeled Temp appears in the
Data table.
To define damage evolution data that depend on field variables, click the
arrows to the right of the Number of field variables field
to increase or decrease the number of field variables.
Field variable columns appear in the
Data table.
Enter damage evolution parameters in the Data table.
You might need to expand the dialog box to see all the columns in the
Data table. For detailed information on how to enter
data, see Entering tabular data.
Click OK to save the damage evolution data and return to
the material editor.