Physical properties of a block for problems of DC Conduction.
The LabelBlockCF object represents physical data applicable to the block label for DC conduction analysis problems.
When you need to set or modify some physical parameters for the block label, you have to get the LabelBlockCF object using the Content property of the Label object, modify the LabelBlockCF object using its properties, and then put it back in the Label object assigning your LabelBlockCF to the Content property of your Label object.
The LabelBlockCF object inherits methods and properties from its base class LabelBlock. In addition, it provides properties specific for the DC conduction analysis. Those are Kxx and Kyy properties that allow getting and setting the electrical conductivity of the media in (S/m = 1 / Ohm·m). Please note that with the LabelBlockCF object you are dealing with a conductivity tensor (not resistivity as in the corresponding dialog box).
You always have to set both Kxx and Kyy properties even for isotropic materials. If the Polar property is set to True, the Kxx component is considered as a radial and Kyy - as tangential component of the conductivity tensor.
Electrical conductivity can depend on temperature. The dependency of conductivity on temperature is given in tabular form, which is automatically approximated by a cubic spline. When the conductivity depends on temperature, the material is considered as isotropic.
The Spline object represents the functional dependency of one variable from another. You use the ConductivitySpline property to get or set the conductivity spline. If the spline does not yet exist, the ConductivitySpline property returns Nothing. In that case you have to first create a new spline using the CreateConductivityCurve and then assign the returned object to the ConductivitySpline property.
The NonLinearConductivity property (of Boolean type, read-only) returns True, when the conductivity depends on temperature for this label.
The TemperatureEx property of type Variant sets/returns a priory known temperature in the block given by a number or a formula of coordinates. The formula should always give positive value.
Dim ELC As QuickField.Application
Set ELC = CreateObject("QuickField.Application")
Dim pbm As QuickField.Problem
Set pbm = ELC.Problems.Open("CF_Example1.pbm")
Dim lbl As QuickField.Label ' the block label
Dim cnt As QuickField.LabelBlockCF ' the label's content
Dim curve As QuickField.Spline ' the conductivity vs. temperature curve
' Create the new block label named "Step"
Set lbl = pbm.Labels(qfBlock).Add
lbl.Name = "Step"
Set cnt = lbl.Content
' Create a new curve (initially empty)
Set curve = cnt.CreateConductivityCurve
' Adding two point to the curve
curve.Add ELC.PointXY(20, 56000000#)
curve.Add ELC.PointXY(100, 46110000#)
' Assign the curve to the label content
cnt.ConductivitySpline = curve
' Define the temperature as a function of coordinates
cnt.TemperatureEx = "20 + 55*step(y-0.25)"
' Remember all changes made in the label's content.
lbl.Content = cnt