Ductile damage

The Ductile damage initiation criterion is a model for predicting the onset of damage due to nucleation, growth, and coalescence of voids in ductile metals. The model assumes that the equivalent plastic strain at the onset of damage is a function of stress triaxiality and strain rate. The ductile criterion can be used in conjunction with the Mises, Johnson-Cook, Hill, and Drucker-Prager plasticity models, including equation of state.

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Damage Initiation for Ductile Metals
  1. From the menu bar in the Edit Material dialog box, select Mechanical Damage for Ductile Metals Ductile Damage .

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

  2. Enter the material parameter, Accumulation power, equal to the value of the power coefficient, N.
  3. To define material damage data that depend on the lode angle, toggle on Use lode-dependent data.

    A column labeled lode-dependent appears in the Data table.

  4. To define material damage data that depend on temperature, toggle on Use temperature-dependent data.

    A column labeled Temp appears in the Data table.

  5. To define behavior 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.

  6. Enter damage parameters in the Data table:

    Fracture Strain

    Equivalent fracture strain at damage initiation.

    Stress Triaxiality

    The stress triaxiality is defined as η = - p / q , where p is the pressure stress and q is the Mises equivalent stress.

    Strain Rate

    The equivalent plastic strain rate, ε ¯ ˙ p ⁢ l .

    Temp

    Temperature, θ .

    Field n

    Predefined field variables.

    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.

  7. Select Suboptions Damage Evolution to define the material degradation that takes place once damage begins.

    For more information, see Damage evolution.”

  8. Click OK to exit the material editor.