In the Soil Plasticity subnode you define the properties for modeling materials exhibiting soil plasticity. This material model can be used together with
Linear Elastic Material and
Nonlinear Elastic Material. It is available with the Geomechanics Module.
Select a Yield criterion —
Drucker-Prager,
Mohr-Coulomb,
Matsuoka-Nakai, or
Lade-Duncan. Most values are taken
From material. For
User defined choices, enter other values or expressions.
In the standard Drucker-Prager formulation, the material parameters are given in terms of the α and
k coefficients. Often material data is expressed in the parameters
c and
used in the Mohr-Coulomb model. You can the choose to use there parameters instead. If so, select the
Match to Mohr-Coulomb criterion check box (see
Mohr-Coulomb Criterion). If this check box is selected, the default values for
Cohesion c and the
Angle of internal friction 
are taken
From material.
If required, select the Use dilatation angle in plastic potential check box. If this check box is selected, then enter a value or expression for the
Dilatation angle ψ. Alternatively, select
From material. The dilatation angle replaces the angle of internal friction when defining the plastic potential.
If the Match to Mohr-Coulomb criterion check box is
not selected, then the default
Drucker-Prager alpha coefficient and
Drucker-Prager k coefficient are taken
From material.
If required, select the Include elliptic cap check box. Select from the list the hardening model. When
Perfectly plastic (no hardening) is selected, enter values or expressions to define the semi-axes of the ellipse under
Elliptic cap parameter pa and
Elliptic cap parameter pb. When
Isotropic hardening is selected from the list, the default
Isotropic hardening modulus Kiso, the
Maximum plastic volumetric strain εpvol,max, and the
Ellipse aspect ratio R are taken
From material (see
Elliptic Cap With Hardening). Enter a value or expression to define the initial semi-axis of the ellipse under the
Initial location of the cap pb0.
If required, select the Use dilatation angle in plastic potential check box. If this check box is selected, then enter a value or expression for the
Dilatation angle ψ. Alternatively, select
From material. The dilatation angle replaces the angle of internal friction when defining the plastic potential.
If required, select the Include elliptic cap check box. Select from the list the hardening model. When
Perfectly plastic (no hardening) is selected, enter values or expressions to define the semi-axes of the ellipse under
Elliptic cap parameter pa and
Elliptic cap parameter pb. When
Isotropic hardening is selected from the list, the default
Isotropic hardening modulus Kiso, the
Maximum plastic volumetric strain εpvol,max, and the
Ellipse aspect ratio R are taken
From material (see
Elliptic Cap With Hardening). Enter a value or expression to define the initial semi-axis of the ellipse under the
Initial location of the cap pb0.
If required, select the Match to Mohr-Coulomb criterion check box. If this check box is selected, the default
Angle of internal friction 
is taken
From material.
If the Match to Mohr-Coulomb criterion check box is
not selected, then the default
Matsuoka-Nakai mu coefficient μ is taken
From material.
If required, select the Match to Mohr-Coulomb criterion check box. If this check box is selected, then enter a value or expression for the
Angle of internal friction φ. Alternatively, select
From material.
If the Match to Mohr-Coulomb criterion check box is
not selected, then the default
Lade-Duncan k coefficient k is taken
From material.
If required, select the Include tension cut-off check box (see
Tension Cut-Off). Enter a value or expression for the
Max tensile stress σt. Use this to constrain the soil plasticity model with an extra yield surface, which limits the maximum principal stress.
Physics tab with Linear Elastic Material or
Nonlinear Elastic Material node selected in the model tree:
Attributes>Soil plasticity
and 