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*CAP PLASTICITY
Specify the Modified Drucker-Prager/Cap plasticity model.

This option is used to define yield surface parameters for elastic-plastic materials that use the modified Drucker-Prager/Cap plasticity model. It must be used in conjunction with the *CAP HARDENING option and, if creep material behavior is included in an Abaqus/Standard analysis, with the *CAP CREEP option.

Products: Abaqus/Standard  Abaqus/Explicit  Abaqus/CAE  

Type: Model data

Level: Model  

Abaqus/CAE: Property module

References:

Optional parameter:

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies, in addition to temperature, included in the definition of the Drucker-Prager/Cap parameters. If this parameter is omitted, it is assumed that the Drucker-Prager/Cap parameters are constant or depend only on temperature. See “Specifying field variable dependence” in “Material data definition,” Section 21.1.2 of the Abaqus Analysis User's Guide, for more information.

Data lines to define Drucker-Prager/Cap plasticity yield surface parameters: 

First line:

  1. Material cohesion, d, in the p–t plane (Abaqus/Standard) or in the p–q plane (Abaqus/Explicit). (Units of FL–2.)

  2. Material angle of friction, , in the p–t plane (Abaqus/Standard) or in the p–q plane (Abaqus/Explicit). Give the value in degrees.

  3. Cap eccentricity parameter, R. Its value must be greater than zero (typically ).

  4. Initial cap yield surface position on the volumetric inelastic strain axis, .

  5. Transition surface radius parameter, . Its value should be a small number compared to unity. If this field is left blank, the default of 0.0 is used (i.e., no transition surface). If creep properties are included in the material model, must be set to zero.

  6. (Not used in Abaqus/Explicit) K, the ratio of the flow stress in triaxial tension to the flow stress in triaxial compression. The value of K should be such that . If this field is left blank or a value of 0.0 is entered, the default of 1.0 is used. If creep properties are included in the material model, K should be set to 1.0.

  7. Temperature.

  8. First field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than one):

  1. Second field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the Drucker-Prager/Cap parameters on temperature and other predefined field variables.