Datum Dependent Properties
In the Define Material Properties dialog, the Datum Dependent option allows you to define material properties which vary linearly with depth from a user-defined datum elevation, or linearly with radial distance from a user-defined center. The following properties can be specified as Datum Dependent:
- Young's Modulus (only if the material Elastic Type = Isotropic)
- Cohesion and Friction Angle (only if Failure Criterion = Mohr-Coulomb and Material Type = Plastic).
To define Datum Dependent properties for a material:
- Select the Datum Dependent check box in the Define Material Properties dialog.
- Select the Define Properties button and you will see the Datum Dependent Properties dialog, in which you can define the datum dependent properties as described below.
Young's Modulus
To define Young's Modulus as a Datum Dependent property, select the Young's Modulus check box in the Datum Dependent Properties dialog, and enter the following parameters.
Datum Type
You can choose either Depth or Radial. If the Datum Type = Depth you can define properties which vary linearly with depth from a user-defined datum elevation. If the Datum Type = Radial, you can define properties which vary linearly with radial distance from a user-defined center.
Datum
The datum elevation (y-coordinate) if the Datum Type = Depth.
Center X / Center Y
The X and Y coordinates of the center point if the Datum Type = Radial.
Young's Modulus at Datum
The value of Young's Modulus at the Datum elevation (if Datum Type = Depth) or Datum center (if Datum Type = Radial). NOTE: this value is entered in the Define Material Properties dialog. It cannot be edited in the Datum Dependent Properties dialog.
Change
The rate of change of Young's Modulus with (vertical) distance from the Datum (if Datum Type = Depth) or with radial distance from the center point (if Datum Type = Radial). You can enter a positive or negative value to indicate increasing or decreasing rate of change with distance.
Cutoff / Cutoff Value
If you wish to specify a maximum (or minimum) value of Young's Modulus, select the Cutoff check box and enter a Cutoff Value. NOTE: if the rate of Change is positive, then the Cutoff Value represents the maximum Young's Modulus. If the rate of Change is negative, then the Cutoff Value represents the minimum Young's Modulus.
Residual Young's Modulus
The value of Residual Young's Modulus at the Datum elevation (if Datum Type = Depth) or Datum center (if Datum Type = Radial). NOTE: this value is entered in the Define Material Properties dialog. It cannot be edited in the Datum Dependent Properties dialog.
NOTE: datum dependent Residual Young's Modulus is only available in the Datum Dependent Properties dialog if the Residual Young's Modulus check box has been selected in the Define Material Properties dialog.
Residual Change
The rate of change of Residual Young's modulus with distance from the datum (elevation or center).
Residual Cutoff / Cutoff Value
You can specify a cutoff value for the Residual Young's modulus, see above for details.
Cohesion
Cohesion can only be defined as a Datum Dependent property for materials with Failure Criterion = Mohr-Coulomb and Material Type = Plastic.
To define Cohesion as a Datum Dependent property, select the Cohesion check box in the Datum Dependent Properties dialog, and enter the following parameters.
Datum Type
You can choose either Depth or Radial. If the Datum Type = Depth you can define properties which vary linearly with depth from a user-defined datum elevation. If the Datum Type = Radial, you can define properties which vary linearly with radial distance from a user-defined center.
Datum
The datum elevation (y-coordinate) if the Datum Type = Depth.
Center X / Center Y
The X and Y coordinates of the datum center if the Datum Type = Radial.
Peak Cohesion at Datum
The value of Cohesion (peak) at the Datum elevation (if Datum Type = Depth) or Datum center (if Datum Type = Radial). NOTE: this value is entered in the Define Material Properties dialog. It cannot be edited in the Datum Dependent Properties dialog.
Peak Change
The rate of change of Cohesion (peak) with (vertical) distance from the Datum (if Datum Type = Depth) or with radial distance from the center point (if Datum Type = Radial). You can enter a positive or negative value to indicate increasing or decreasing rate of change with distance.
Peak Cutoff / Cutoff Value
If you wish to specify a maximum (or minimum) value of Cohesion, select the Peak Cutoff check box and enter a Peak Cutoff Value. NOTE: if the rate of Change is positive, then the Cutoff Value represents the maximum peak cohesion. If the rate of Change is negative, then the Cutoff Value represents the minimum peak cohesion.
Residual Cohesion at Datum
The value of Cohesion (residual) at the Datum elevation (if Datum Type = Depth) or Datum center (if Datum Type = Radial). NOTE: this value is entered in the Define Material Properties dialog. It cannot be edited in the Datum Dependent Properties dialog.
Residual Change
The rate of change of Residual Cohesion with distance from the datum (elevation or center).
Residual Cutoff / Cutoff Value
You can specify a cutoff value for the Residual Cohesion, see above for details.
Friction Angle
Friction Angle can only be defined as a Datum Dependent property for materials with Failure Criterion = Mohr-Coulomb and Material Type = Plastic.
To define Friction Angle as a Datum Dependent property, select the Friction Angle check box in the Datum Dependent Properties dialog, and enter the Datum Dependent Friction Angle variables.
The definitions of the Datum Dependent variables for Friction Angle are the same as the definitions for Cohesion - see above for details.