Defining rate-dependent yield with yield stress ratios

Create a material model as described in described in one of the following sections:

• Using an isotropic hardening model to define classical metal plasticity”

• Using the Johnson-Cook hardening model to define classical metal plasticity”

• Defining Drucker-Prager hardening”

From the Suboptions menu in the Edit Material dialog box, select Rate Dependent.

A Suboption Editor appears.

Click the arrow to the right of the Hardening field, and select a method for defining hardening dependencies:

• Select Power Law to define yield stress ratios with the Cowper-Symonds overstress law.

• Select Tabular to enter yield stress ratios directly in tabular form as a function of equivalent plastic strain rates.

• Select Johnson-Cook to use an analytical Johnson-Cook form to define R.

If applicable, toggle on Use temperature-dependent data to define data that depend on temperature.

A column labeled Temp appears in the Data table.

If applicable, 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.

If you selected Power Law from the list of Hardening options, enter the following data in the Data table:

Mulitiplier

Material parameter, D.

Exponent

Material parameter, n.

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.

If you selected Yield Ratio from the list of Hardening options, enter the following data in the Data table:

Yld Stress Ratio

Yield stress ratio, $R=\overline{\sigma }/{\sigma }^0$.

Eq Plastic Strain Rate

Equivalent plastic strain rate, ${\dot{\overline{\epsilon }}}^{pl}$ (or $\left|{\dot{\epsilon }}_{axial}^{pl}\right|$, the absolute value of the axial plastic strain rate in uniaxial compression, for the crushable foam model).

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.

If you selected Johnson-Cook from the list of Hardening options, enter the following data in the Data table:

C

Material constant, C, which is independent of temperature and field variables.

Epsilon dot zero

Material constant, ${\dot{\epsilon }}_0$, which is independent of temperature and field variables.

For detailed information on how to enter data, see Entering tabular data.

Click OK to return to the Edit Material dialog box.