MO Granular

This model is an extension of the Drucker-Prager model that takes into account effects associated with granular materials such as powders, soil and sand. In addition to pressure hardening, the model also represents density hardening and variations in the shear modulus with density.

The yield stress is made up of two components, one dependent on the density and one dependent on the pressure,

where σy, σp and σρ denote the total yield stress, the pressure yield stress and the density yield stress respectively.

The unload/reload slope is defined by the shear modulus which is defined as a function of the zero pressure density of the material.


Note:  The yield stress is defined by a yield stress - pressure and a yield stress - density curve with up to 10 points in each curve.

The shear modulus is defined by a shear modulus - density curve with up to 10 points.

All three curves must be defined.

This model can only be applied to solid bodies.


Table 123:  Input Data

NameSymbolUnitsNotes
Yield Stress vs Pressure StressTabular data
Yield Stress vs Density Stress and DensityTabular data
Shear Modulus vs Density Stress and DensityTabular data

Custom results variables available for this model:

NameDescriptionSolidsShellsBeams
EFF_PL_STNEffective Plastic StrainYes NoNo
PRESSUREPressureYesNoNo
DENSITYDensityYesNoNo

Release 16.2 - © SAS IP, Inc. All rights reserved.