Defining a creep law

If you are performing an Abaqus/Standard analysis, you can define classical deviatoric metal creep behavior either by specifying user subroutine CREEP or by providing parameters for some simple creep laws. See Rate-dependent plasticity: creep and swelling, for more information.

  1. From the menu bar in the Edit Material dialog box, select MechanicalPlasticityCreep.

    (For information on displaying the Edit Material dialog box, see Creating or editing a material.)

  2. Click the arrow to the right of the Law field, and select the creep law of your choice. See Creep behavior, for more information.

  3. Toggle on Use temperature-dependent data to define data that depend on temperature.

    A column labeled Temp appears in the Data table.

  4. Click the arrows to the right of the Number of field variables field to increase or decrease the number of field variables on which the data depend.

  5. If you selected the Strain-Hardening or Time-Hardening creep law, enter the following data in the Data table:

    Power Law Multiplier

    Power law multiplier, A. (Units of F-nL2⁢nT-1-m.)

    Eq Stress Order

    Equivalent deviatoric stress order, n.

    Time Order

    Total time order, m, for the Time-Hardening creep law, or strain order, m, for the Strain-Hardening creep law.

    Temp

    Temperature.

    Field n

    Predefined field variables.

    You may 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.

  6. If you selected the Hyperbolic-Sine creep law, enter the following data in the Data table:

    Power Law Multiplier

    Power law multiplier, A. (Units of T−1.)

    Hyperb Law Multiplier

    Hyperbolic sine law multiplier, B. (Units of F−1L2.)

    Eq Stress Order

    Equivalent stress order, n

    Activation Energy

    Activation energy, △⁢H. (Units of JM−1

    Univeral Gas Const

    Universal gas constant, R. (Units of JM−1θ−1.)

    Temp

    Temperature.

    Field n

    Predefined field variables.

    You may 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.

  7. If desired, select Ornl from the Suboptions menu to implement the creep rules specified by the Oak Ridge National Laboratory constitutive model. See Using the Oak Ridge National Laboratory (ORNL) constitutive model in plasticity and creep calculations” for more information.

  8. If desired, select Potential from the Suboptions menu to specify anisotropic creep behavior. See Defining anisotropic yield and creep” for more information.

  9. Click OK to create the material and to close the Edit Material dialog box. Alternatively, you can select another material behavior to define from the menus in the Edit Material dialog box (see Browsing and modifying material behaviors, for more information).