*POROUS ELASTIC

Optional parameters

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies included in the definition of the parameters, in addition to temperature. If this parameter is omitted, it is assumed that the parameters depend only on temperature.

SHEAR

This parameter is relevant only when TYPE=LOGARITHMIC.

Set SHEAR=G to define the deviatoric behavior with a constant shear modulus G.

Set SHEAR=POISSON (default) to compute the instantaneous shear modulus from the bulk modulus and Poisson's ratio. The Poisson's ratio should be given on the data lines.

STIFFNESS

This parameter is relevant only when TYPE=POWER LAW.

Set STIFFNESS=TANGENT (default) to indicate that the porous elastic material constants define the tangent modulus.

Set STIFFNESS=SECANT to indicate that the porous elastic material constants define the secant modulus.

TYPE

Set TYPE=LOGARITHMIC (default) to define a logarithmic relationship between the pressure and the volumetric elastic strain.

Set TYPE=POWER LAW to define a power-law relationship between the pressure and the Young's modulus.

Data lines to define the deviatoric behavior with a constant shear modulus G for SHEAR=G and TYPE=LOGARITHMIC

First line

Value of the logarithmic bulk modulus, $κ$ . (Dimensionless.)
Value of the shear modulus, G.
Value of the elastic tensile limit, $p_{t}^{e l}$ . (This value cannot be negative.)
Temperature, $θ$ .
First field variable.
Etc., up to four field variables.

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

Fifth 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 material parameters $κ$ , G, and $p_{t}^{e l}$ on temperature and field variables.

Data lines to define the instantaneous shear modulus from the bulk modulus and Poisson's ratio for SHEAR=POISSON and TYPE=LOGARITHMIC

First line

Value of the logarithmic bulk modulus, $κ$ . (Dimensionless.)
Value of Poisson's ratio, $ν$ .
Value of the elastic tensile limit, $p_{t}^{e l}$ . (This value cannot be negative.)
Temperature, $θ$ .
First field variable.
Etc., up to four field variables.

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

Fifth 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 material parameters $κ$ , $ν$ , and $p_{t}^{e l}$ on temperature and field variables.

Data lines for TYPE=POWER LAW

First line

Reference Young's modulus, $E_{r e f}$ .
Reference pressure, $p_{r e f}$ .
Material parameter, $p_{0}$ (units of pressure). This value must satisfy $p_{0} > 0$ and $(p_{r e f} + p_{0}) > 0$ .
Material parameter, $n$ . This value must be greater than or equal to zero.
Poisson's ratio, $ν_{\infty}$ , corresponding to the limit $p \to \infty$ .
Poisson's ratio, $ν_{0}$ , corresponding to $p = 0$ .
Material parameter, $m$ . This value must be greater than zero.
Temperature, $θ$ .

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

First field variable.
Second 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 material parameters on temperature and field variables.