*SOFT ROCK HARDENING

Optional parameters

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies, in addition to temperature, included in the definition of the hydrostatic pressure stress. If this parameter is omitted, the hydrostatic pressure stress may depend only on the volumetric plastic strain and, possibly, on the temperature. See Material Data Definition for more information.

SR

This parameter is relevant only when it is used in conjunction with the SOFTENING REGULARIZATION option.

Set SR=ON (default) to use softening regularization for the soft rock hardening data.

Set SR=OFF if softening regularization is not required.

TYPE

Set TYPE=COMPRESSION (default) to define the hardening behavior by providing the hydrostatic compression yield stress, $p_{c}$ , as a function of volumetric plastic strain.

Set TYPE=TENSION to define the hardening behavior by providing the hydrostatic tension yield stress, $p_{t}$ , as a function of volumetric plastic strain.

Compression hardening must always be defined. Tensile hardening is optional and can be specified, if needed, by repeating the SOFT ROCK HARDENING option with TYPE=TENSION.

Data lines to define hardening for soft rock plasticity

First line

Value of the hydrostatic pressure stress at yield, $p_{c}$ or $p_{t}$ . $p_{c}$ is given as a positive value and must increase with increasing plastic strain. $p_{t}$ can be zero or negative and must decrease with increasing plastic strain.
Absolute value of the corresponding compressive volumetric plastic strain. The first tabular value must always be zero.
Temperature.
First field variable.
Second field variable.
Etc., up to five field variables.

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

Sixth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the yield surface size on volumetric plastic strain and, if needed, on temperature and other predefined field variables.