*POROUS BULK MODULI

Define bulk moduli for soils and rocks.

This option is used to define the bulk moduli of solid grains and a permeating fluid such that their compressibility can be considered in the analysis of a porous medium. The POROUS BULK MODULI option cannot be used with the porous metal plasticity material model. For cohesive elements, this option can be used in conjunction with the ELASTIC, TYPE=TRACTION option to define Biot's coefficient. If this option is omitted, the bulk moduli are assumed to be infinite.

This page discusses:

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Porous Bulk Moduli

ProductsAbaqus/StandardAbaqus/CAE

TypeModel data

LevelModel

Abaqus/CAEProperty module

Optional parameters

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies included in the definition of the porous bulk moduli. If this parameter is omitted, it is assumed that the porous bulk moduli are constant or depend only on temperature.

This parameter is not active for cohesive elements.

Data lines to define bulk moduli

First line

  1. Bulk modulus of solid grains. (Units of FL−2.) If this entry is blank or zero, this value is assumed to be infinite.

  2. Bulk modulus of permeating fluid. (Units of FL−2.) If this entry is blank or zero, this value is assumed to be infinite.

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

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

  1. Sixth 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 porous bulk moduli on temperature and other predefined field variables.

Data line for cohesive elements

First (and only) data line

  1. E s ⁢ o . (Units of FL−2.)

    Biot’s coefficient then follows from the identity α 0 = 1 − E n ⁢ n / E s ⁢ o , where E n ⁢ n is given by the ELASTIC, TYPE=TRACTION option.