Müschenborn-Sonne forming limit diagram (MSFLD) damage

The MSFLD damage initiation criterion is used to predict sheet metal forming limits for arbitrary loading paths. The model works on the basis of equivalent plastic strain and assumes that the forming limit curve represents the sum of the highest attainable equivalent plastic strains. The approach requires transforming the original forming limit curve (without predeformation effects) from the space of major versus minor strains to the space of equivalent plastic strain, ε ¯ p ⁢ l , versus the ratio of principal strain rates, α = ε ˙ minor / ε ˙ major .

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Damage Initiation for Ductile Metals

Context:

Damage due to bending deformation cannot be evaluated using this model. For more information, see Damage Initiation for Ductile Metals.

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

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

  2. Choose one of the following Definitions:

    • Select MSFLD to enter data in the form of equivalent plastic strains and ratios of minor to major strain rates.

    • Select FLD to enter data in the form of major and minor principal strains and the equivalent plastic strain and to have Abaqus transform the data into the Müschenborn-Sonne form.

  3. Enter the material parameter, Accumulation power, equal to the value of the power coefficient, N.
  4. If desired, you can change the value of ω ( 0 < ω ≤ 1 ). Omega is used to filter the ratio of principal strains rates, preventing the ratio from jumping to a higher value due to sudden changes in the strain direction (deformation path); the default value is ω = 1 .
  5. To define material damage data that depend on temperature, toggle on Use temperature-dependent data.

    A column labeled Temp appears in the Data table.

  6. 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.

  7. Enter damage parameters in the Data area (parameters followed by MSFLD or FLD are used only for that definition type):

    Plastic Strain at Initiation (MSFLD)

    Equivalent plastic strain at initiation of localized necking.

    Ratio of Principal Strains (MSFLD)

    Ratio of minor to major principal strains, α .

    Major Principal Strain (FLD)

    Major principal strain at damage initiation.

    Minor Principal Strain (FLD)

    Minor principal strain at damage initiation.

    Plastic Strain Rate

    Equivalent plastic strain rate.

    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.

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

    For more information, see Damage evolution.”

  9. Click OK to exit the material editor.