Combined uniaxial tension and compression data can be used to model material behavior that is different
in tension than in compression, but such data can only be used in combination with pressure-volume
experimental data.
Volumetric behavior is specified with either experimental data or a polynomial volumetric potential
function. Incompressible behavior results if no volumetric model or data is given.
Volumetric experimental data is input as two values per data point with volume ratio as the independent
variable and pressure as the dependent variable. For uniaxial tension, uniaxial compression, equibiaxial
tension, planar shear, and combined uniaxial tension and compression deformations, the experimental
data is entered in either of these formats:
- Two values per data point: engineering strain as the independent variable and engineering stress as the
dependent variable - Three values per data point: engineering strain in the loading direction as the independent variable, en-
gineering strain in the lateral direction as the first dependent variable, and engineering stress as the
second dependent variable. For uniaxial compression data, the lateral strain is ignored and incompressib-
ility is assumed for the experimental data.
The input format must be consistent within the table for an individual experimental deformation, but
can change between tables for different experimental deformations.
For example, incompressible uniaxial tension and planar shear data are used as input to the response
function hyperelastic material defined above. Three experimental data points for incompressible uniaxial
deformation are input with the following commands:
TB,EXPERIMENTAL,1,,,UNITENSION! Activate uniaxial data table
TBFIELD,TEMP,21! Temperature for following data
TBPT,, 0.0, 0.0!
TBPT,, 0.2, 1.83! 1st data point
TBPT,, 1.0, 5.56! 2nd data point
TBPT,, 4.0, 17.6! 3rd data pointFour experimental data points for incompressible planar shear deformation are input with the following
commands:
TB,EXPERIMENTAL,1,,,SHEAR! Activate planar shear data table
TBFIELD,TEMP,21! Temperature for following data
TBPT,, 0.0, 0.0!
TBPT,, 0.24, 2.69! 1st data point
TBPT,, 0.96, 6.32! 2nd data point
TBPT,, 4.2, 19.7! 3rd data point
TBPT,, 5.1, 27.4! 4th data pointCombined uniaxial tension and compression are input via TBOPT = UNIAXIAL on the TB,EXPE command,
as shown in this example:
TB,EXPE,1,,,UNIAXIAL! Activate uniaxial data table
TBFIELD,TEMP,21! Temperature for following data
TBPT,, 0.0, 0.0!
TBPT,, 0.01, 0.0915! 1st tension data point
TBPT,, 0.2, 1.83! 2nd tension data point
TBPT,, 1.0, 5.56! 3rd tension data point
TBPT,, -0.01, -0.0915! 1st compression data point
TBPT,, -0.2, -3.66! 2nd compression data point
TBPT,, -1.0, -22.24! 3rd compression data pointFor all input data, the zero stress-strain point should be entered as a data point; otherwise, interpolation
or extrapolation of the data to zero strain should yield a value of zero stress. For combined tension and
compression data, the initial slope of the data should be the same in tension and compression.
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationModeling Material Nonlinearities