Regions, Constitutive Models, and Properties

Divide the model into regions that have distinct materials, construction stages, loading conditions, or output requirements. Assign clear group names such as Soil, Rock, Footing, Excavation, and Runout. Groups make command ranges repeatable and reduce reliance on coordinate ranges that may become invalid after large deformation.

Direct MPoint assignment

The command mpoint cmodel assign assigns a constitutive model to the selected material points. The command mpoint property assigns the properties recognized by that model. Assign the constitutive model before its properties.

mpoint cmodel assign mohr-coulomb range group 'Soil'

mpoint property density 2000 ...
    young 50e6 poisson 0.30 ...
    cohesion 10e3 friction 30 dilation 0 ...
    range group 'Soil'

An elastic footing may be assigned separately:

mpoint cmodel assign elastic range group 'Footing'
mpoint property density 2400 young 25e9 poisson 0.20 ...
    range group 'Footing'

Zone-based assignment before import

For a zone-created model, use zone cmodel assign and zone property before mpoint import.

zone cmodel assign mohr-coulomb range group 'Soil'
zone property density 2000 young 50e6 poisson 0.30 ...
    cohesion 10e3 friction 30 range group 'Soil'

mpoint import from-zones

The imported material points normally inherit the zone constitutive model, properties, density, and groups. If an import option skips any of these quantities, assign them explicitly afterward.

Constitutive Model Selection

The constitutive model should be selected according to the expected material behavior. The selected model is assigned to the material points using mpoint cmodel assign, and its required parameters are subsequently specified using mpoint property; the constitutive model must be assigned before its properties are entered. Users should consult the Constitutive Models documentation to review the available elastic and plastic models, their assumptions, required parameters, limitations, and verification examples, and then apply the model that best represents the physical material and loading conditions of the MPoint2D or MPoint3D analysis.

Recommended assignment checks

After model assignment:

• list or plot material groups;

• plot constitutive-model names;

• inspect density and stiffness distributions;

• confirm strength units and angle units;

• verify that no active material point has a null model or zero density;

• perform a one-element or small-domain constitutive test when using a new model or a new property set.

Material changes during staged analysis

Use mpoint cmodel assign and mpoint property with group ranges to change material behavior during a construction sequence. Save the model before a major change. When replacing a constitutive model, determine whether stress, plastic strain, hardening variables, pore pressure, and other state variables remain meaningful after the change.