*UNIAXIAL TEST DATA

Used to provide uniaxial test data (compression and/or tension).

This option is used to provide uniaxial test data. It can be used only in conjunction with the *FABRIC HYPERELASTIC option, the HYPERFOAM option, the LOW DENSITY FOAM option, and the MULLINS EFFECT option.

This page discusses:

Using uniaxial test data to define a hyperelastic material
Using uniaxial test data to define an elastomeric foam
Using uniaxial test data to define a low-density foam material
Using uniaxial test data to define the Mullins effect material model

Using uniaxial test data to define a hyperelastic material

Optional parameters

SMOOTH

Include this parameter to apply a smoothing filter to the stress-strain data. If the parameter is omitted, no smoothing is performed.

Set this parameter equal to the number n such that $2 n + 1$ is equal to the total number of data points in the moving window through which a cubic polynomial is fit using the least-squares method. n should be larger than 1. The default is SMOOTH=3.

Optional parameter when the UNIAXIAL TEST DATA option is used in conjunction with the HYPERELASTIC, MARLOW option or the HYPERELASTIC, VALANIS-LANDEL option

DEPENDENCIES: Set this parameter equal to the number of field variable dependencies included in the definition of the test data. If this parameter is omitted, it is assumed that the test data depend only on temperature.

Data lines to specify uniaxial test data for hyperelasticity other than the Marlow model and Valanis-Landel model (the nominal strains must be arranged in either ascending or descending order if the SMOOTH parameter is used)

First line

Nominal stress, $T_{U}$ .
Nominal strain, $ϵ_{U}$ .

Repeat this data line as often as necessary to give the stress-strain data.

Data lines to specify uniaxial test data for the Marlow model or the Valanis-Landel model (the nominal strains must be arranged in ascending order if the SMOOTH parameter is used)

First line

Nominal stress, $T_{U}$ .
Nominal strain, $ϵ_{U}$ .
Nominal lateral strain, $ϵ_{2} = ϵ_{3}$ . Not needed if the POISSON parameter is specified on the HYPERELASTIC option or if the VOLUMETRIC TEST DATA option is used.
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the test data as a function of temperature and other predefined field variables. Nominal strains and nominal stresses must be given in ascending order.

Using uniaxial test data to define an elastomeric foam

There are no parameters associated with this option.

Data lines to specify uniaxial test data for a hyperfoam

First line

Nominal stress, $T_{L}$ .
Nominal strain, $ϵ_{U}$ .
Nominal lateral strain, $ϵ_{2} = ϵ_{3}$ . Default is zero. Not needed if the POISSON parameter is specified on the HYPERFOAM option.

Repeat this data line as often as necessary to give the stress-strain data.

Using uniaxial test data to define a low-density foam material

Required parameters

DIRECTION

Set DIRECTION=TENSION to define tensile behavior.

Set DIRECTION=COMPRESSION to define compressive behavior.

Optional parameters

DEPENDENCIES: Set this parameter equal to the number of field variable dependencies included in the definition of the test data. If this parameter is omitted, it is assumed that the test data depend only on temperature.

Data lines to specify uniaxial test data for LOW DENSITY FOAM, LATERAL STRAIN DATA=NO

First line

Nominal stress, $T_{U}$ . (Provide the absolute value if DIRECTION=COMPRESSION.)
Nominal strain, $ϵ_{U}$ . (Provide the absolute value if DIRECTION=COMPRESSION.)
Nominal strain rate, ${\dot{ϵ}}_{U}$ . (Provide positive values to specify the loading response and negative values to specify unloading.)
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the test data as a function of temperature and other predefined field variables. Nominal strains, nominal strain rates and nominal stresses must be given in ascending order.

Data lines to specify uniaxial test data for LOW DENSITY FOAM, LATERAL STRAIN DATA=YES

First line

Nominal stress, $T_{U}$ . (Provide the absolute value if DIRECTION=COMPRESSION.)
Nominal strain, $ϵ_{U}$ . (Provide the absolute value if DIRECTION=COMPRESSION.)
Nominal lateral strain, $ϵ_{2} = ϵ_{3}$ . Default is zero. The value must be negative if DIRECTION=TENSION and positive if DIRECTION=COMPRESSION. (A negative Poisson's ratio is not supported for this model.)
Nominal strain rate, ${\dot{ϵ}}_{U}$ . (Provide positive values to specify the loading response and negative values to specify unloading.)
Temperature, $θ$ .
First field variable.
Second field variable.
Third field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than three)

Fourth field variable.
Etc., up to eight field variables per line.

Using uniaxial test data to define the Mullins effect material model

There are no parameters associated with this option.

Data lines to specify uniaxial test data for defining the unloading-reloading response of the Mullins effect material model

First line

Nominal stress, $T_{L}$ .
Nominal strain, $ϵ_{U}$ .

Repeat this data line as often as necessary to give the stress-strain data.