Specifying Creep Behavior

When you create a linear elastic material model with creep specified, you can select one of a series of supported creep laws, or you can use a user subroutine to describe a custom creep behavior.

Before you begin: Create a linear elastic data material model with creep.
See Also
Specifying the Material Model in the Numerical and FE Execution Modes
In Other Guides
CREEP
  1. From the Calibration Tools section of the action bar, click Material Model .
    The Material Model dialog box opens.
  2. Optional: Enter a descriptive Name.
  3. From the list at the top of the Material Model dialog box, select numerical execution mode .
    The dialog box updates the list of models to show the set that you can define in numerical execution mode.
  4. From the available material models, select Linear Elastic > Elastic-Creep.
  5. Click OK.
    Elastic and Creep options appear in the Calibration Setup dialog box
  6. If you want to define creep behavior using any creep model other than user-defined creep, do the following:

    For more information about each creep law, see About Creep and Creep Models.

    1. From the Law options in the Creep section, select the creep law you want to use from the following options:

      Creep Law Description
      Hyperbolic-Sine Shows exponential dependence on the stress at high stress levels and reduces to the power-law at low stress levels (with no explicit time dependence).
      Anand Defines creep using strain rate and temperature.
      Darveaux Involves both primary and secondary creep.
      Double Power Models creep in a manner equivalent to the strain hardening form.
      Power Law Models creep in a manner equivalent to the strain hardening form.
      Time Power Law Models creep in a manner equivalent to the time hardening form.

      For more information about each creep law, see About Creep and Creep Models.

    2. Adjust the creep parameters that appear to customize the selected creep behavior.
  7. For user-defined creep behavior, do the following to specify the custom creep schema you want to use:
    1. From the Law options in the Creep section, select User.
    2. Select Use custom schema.
    3. To select a schema that is already in the database, click and select the schema from the search results.
    4. To add a new schema, click , upload the new schema file from the Import Custom Schema dialog box, and accept the default values that appear in the Engineering Document dialog box that appears.

      A sample schema is available in Sample Schema for Calibrating Creep.

    5. Click to view the schema in the Creep section.

Sample Schema for Calibrating Creep 

<UserSchema>
    <ParameterTableType name=”MTR1”>
        <Schema type=”float” name=”A” units=”RATE”/>
        <Schema type=”float” name=”Sig0” units=”STRESS”/>
        <Schema type=”float” name=”An” units=”DIMENSIONLESS”/>
    </ParameterTableType>
    <AnalysisData>
        <TableCollection>
            <ParameterTable type=”MTR1”/>
        </TableCollection>
    </AnalysisData>
</UserSchema>