Criteria Settings

Overview of the criteria settings used in QI (quality index) and batch meshing, and in QI-based element checks.

Configure criteria settings using the Criteria Editor. Criteria settings can be saved to a file, and loaded for subsequent editing.

Access
Right-click on the Element Quality legend and select Edit Criteria.


Figure 1.

Switch between 2D and 3D criteria from the tree on the left of the dialog.

General criteria settings include:
Target element size
Desired element size for the mesh.
Recalculate min and max size fail values
Recalculates the minimum and maximum size values in the criteria file based on a newly entered value in the target element size.
Minimum size is recalculated as 40% of the target size and Maximum element size calculated as 175% of the target size as per recommended values. You can edit these values manually by turning this option off.
Legacy file import is not affected by this option. The min and max size values are recalculated only when you change the target element size value with this option turned on.
Row Up, Row Down (, )
Change the display order of criteria in the Element Quality Criteria legend.
Tip: If you change the order of the element criteria after you have adjusted the threshold values in the Criteria legend, the threshold values will reset to their fail values. It is best to change the order of the element criteria first, and then change the threshold values in the Criteria legend.
Calculation method
Select the solver to be used when calculating criteria checks.
Time step calculator ()
Minimum length calculator, based on TimeStep, which can be used to calculate the suggested minimum length, based on a material, time step, scale factor, Young's modulus, Poisson's ratio, and density.
A pre-defined material can be selected, or a custom material can be defined.
Apply the calculated minimum length by selecting the Use min length from timestep calculator checkbox.
Checks can be defined in the table. Each check is displayed in the Checks column, and the controls and values associated with each check are displayed in the subsequent columns to the right.
On
In the On column, use the checkbox to turn each individual check on/off.
Color
Click on the color swatch and select a new color for the element or the legend.

This can also be done by clicking a color swatch in the Element Quality legend.

Calculation method
Select a calculation method to apply for certain checks. Available methods may vary for each check. Click inside each Calculation Method list box to see if alternative methods are available for each Checks entry.
The different solver calculation methods are described in How Element Quality is Calculated. The Chordal Deviation check is currently ignored when performing batch meshing or QI meshing. It is only used to calculate the QI value from the Quality Index panel.
Fail value
In the Fail column, edit the fail value for each specific check.
Ideal, good, warn, worst, and weight value
The Ideal, Good, Warn, and Worse fields are interpolated or extrapolated automatically.
Select the Advanced checkbox to access the Weight, Ideal, Good, Warn and Worst columns and edit each check's corresponding value.
Such changes modify how the quality index value is calculated, but do not significantly impact the final mesh. Weight factors are also adjustable, but they also do not make a large difference in the final mesh, unless they are set to an order of magnitude higher than the others. Default values for the weight factors are recommended.