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*CLAY PLASTICITY
Specify the extended Cam-clay plasticity model.

This option is used to specify the plastic part of the material behavior for elastic-plastic materials that use the extended Cam-clay plasticity model.

Products: Abaqus/Standard  Abaqus/Explicit  Abaqus/CAE  

Type: Model data

Level: Model  

Abaqus/CAE: Property module

References:

Optional parameters:

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies, in addition to temperature, included in the definition of the Cam-clay parameters. If this parameter is omitted, the Cam-clay parameters may 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.

HARDENING

Set HARDENING=EXPONENTIAL (default for Abaqus/Standard) to specify an exponential hardening/softening law. This hardening law is not supported in Abaqus/Explicit.

Set HARDENING=TABULAR (default and only option for Abaqus/Explicit) to specify a piecewise linear hardening/softening relationship. The *CLAY HARDENING option must be used in this case. HARDENING=TABULAR and the use of the INTERCEPT parameter are mutually exclusive.

INTERCEPT

This parameter applies only to Abaqus/Standard analyses.

It is used as an alternative to the direct specification of the initial yield surface size, , when the exponential hardening law is specified. Set this parameter equal to , the intercept of the virgin consolidation line with the void ratio axis in a plot of void ratio versus the logarithm of pressure stress. If this parameter is included, the value given for on the data line is ignored. This parameter cannot be used when the HARDENING=TABULAR parameter is used.

Data lines to define Cam-clay plasticity: 

First line:

  1. Logarithmic plastic bulk modulus, (dimensionless). This data item is ignored if HARDENING=TABULAR.

  2. Stress ratio at critical state, M.

  3. Enter the initial yield surface size, (units of FL–2), if HARDENING=EXPONENTIAL. Enter the initial volumetric plastic strain, corresponding to according to the *CLAY HARDENING definition if HARDENING=TABULAR. A positive value must be entered. This data item is ignored if the INTERCEPT parameter is included.

  4. , the parameter defining the size of the yield surface on the “wet” side of critical state. If this value is omitted or set to zero, a value of 1.0 is assumed.

  5. K, the ratio of the flow stress in triaxial tension to the flow stress in triaxial compression. . If this value is left blank or set to zero, a value of 1.0 is assumed.

  6. Temperature.

  7. First field variable.

  8. Second field variable.

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

  1. Third 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 Cam-clay parameters on temperature and other predefined field variables.