5.1.1.5. Property Descriptions

The properties and options available in the Details pane are described below.

Category Properties/Options/Description

Category	Properties/Options/Description
Scope	Scoping Method options: Geometry Selection: Nonlinear Adaptive Region is applied to a geometry or geometries, selected using a graphical selection tool (default). Geometry: Visible when the Scoping Method property is set to Geometry Selection. Displays the type of geometry (Body) and the number of geometric entities (1 Body, 2 Bodies) that the Nonlinear Adaptive Region has been applied to. Named Selection: Indicates that the geometry selection is defined by a Named Selection. Named Selection: Visible when the Scoping Method property is set to Named Selection. This field provides a drop-down list of available user-defined element-based (only) Named Selections. You may wish to review the Mechanical APDL References and Notes section for specific command execution information regarding these selections.
Definition	Criterion: Options included Energy, Box, or Mesh. Energy If Energy is selected, you need to enter an Energy Coefficient. Energy Coefficient: This criterion checks the strain energy of any element that is part of the defined component using the following calculation. A component is defined as the assembly of all scoped elements. where: E_e = strain energy of single target element. c₁ = user input energy coefficient. E_total = total strain energy of the component. NUME = number of elements of the component. If this criterion is satisfied at an element, the program refines the element. A smaller Energy Coefficient improves the potential to trigger the mesh regeneration for the same loads. Box If Box is selected, the following additional properties require entries: Coordinate System (default is Global Coordinate System): defines the minimum values of the box. Length X: defines the diagonal length on global X axis. Length Y: defines the diagonal length on global Y axis. Length Z (for 3D): defines the diagonal length on global Z axis. Mesh (3D Analysis) For 3D analyses, if you select the Mesh option, the Tetrahedral and Hex-Dominant categories display. Tetrahedral The Options property displays. Available options include Skewness, Jacobian Ratio, or Skewness and Jacobian Ratio (default. If the Options property is set to either Skewness or Skewness and Jacobian Ratio, you need to enter a Skewness Value for the mesh elements. The element skewness is defined as: Skewness = (V_reg - V_el) / V_reg Where: V_el is the volume of the element under calculation and V_reg is the volume of the standard tetrahedral linear element located in the same sphere as the element under calculation. When the element under calculation has an ideal shape (that of a standard tetrahedral element), V_reg = V_el and Skewness Value = 0. When the element under calculation has the least ideal shape (that of a flat element), V_el = 0 and Skewness Value = 1. Therefore, for the linear tetrahedral element, Skewness Value is always between 0 and 1, with 1 being a flat element. The default value is 0.9. The recommended Skewness Value is approximately 0.85 to 0.9. When the Option property is set to Jacobian Ratio or Skewness and Jacobian Ratio, you need to enter a Jacobian Ratio Value for the mesh elements. This value defines the maximum Jacobian ratio at element integration points. The default value is `0.1`. Hex-Dominant If the body selected in the scoping includes hexahedral mesh, then this category and its properties are applicable to solution processing. The application uses an initial hexahedral-dominant mesh which is converted to a tetrahedral mesh during the solution process once the category’s criterion is met. For a tetrahedral only mesh, application ignores this category and its properties. For this category: The Options property is read-only and the application sets it to Shape. The Maximum Corner Angle property has the default setting of `155°`. The entry range for this property is `0°` - `180°`. An element is re-meshed when any of its corner angles reach this specified value. Mesh (2D Analysis) For 2D analyses: The Options property is read-only and the application sets it to Shape. The Maximum Corner Angle property has the default setting of `160°` (recommended). The entry range for this property is `0°` - `180°`. An element is re-meshed when any of its corner angles reach this specified value. All the following common criteria properties are available for all Criterion property options as well as 2D analyses: Check At: Options included Equally Spaced Points or Specified Recurrence Rate. Value: This property further defines the Check At property. The default value is `1`. Time Range: options included Entire Load Step or Manual. When specified as Manual, you need to enter a Start Time and End Time. The End Time value must be larger than the Start Time value. Suppressed: Include (No - default) or exclude (Yes) the condition.

Scope

Scoping Method options:

Geometry Selection: Nonlinear Adaptive Region is applied to a geometry or geometries, selected using a graphical selection tool (default).
Geometry: Visible when the Scoping Method property is set to Geometry Selection. Displays the type of geometry (Body) and the number of geometric entities (1 Body, 2 Bodies) that the Nonlinear Adaptive Region has been applied to.
Named Selection: Indicates that the geometry selection is defined by a Named Selection.
Named Selection: Visible when the Scoping Method property is set to Named Selection. This field provides a drop-down list of available user-defined element-based (only) Named Selections.

You may wish to review the Mechanical APDL References and Notes section for specific command execution information regarding these selections.

Definition

Criterion: Options included Energy, Box, or Mesh.

Energy

If Energy is selected, you need to enter an Energy Coefficient.

Energy Coefficient: This criterion checks the strain energy of any element that is part of the defined component using the following calculation. A component is defined as the assembly of all scoped elements.

where:

E_e = strain energy of single target element.
c₁ = user input energy coefficient.
E_total = total strain energy of the component.
NUME = number of elements of the component.

If this criterion is satisfied at an element, the program refines the element. A smaller Energy Coefficient improves the potential to trigger the mesh regeneration for the same loads.

Box

If Box is selected, the following additional properties require entries:

Coordinate System (default is Global Coordinate System): defines the minimum values of the box.
Length X: defines the diagonal length on global X axis.
Length Y: defines the diagonal length on global Y axis.
Length Z (for 3D): defines the diagonal length on global Z axis.

Mesh (3D Analysis)

For 3D analyses, if you select the Mesh option, the Tetrahedral and Hex-Dominant categories display.

Tetrahedral

The Options property displays. Available options include Skewness, Jacobian Ratio, or Skewness and Jacobian Ratio (default.

If the Options property is set to either Skewness or Skewness and Jacobian Ratio, you need to enter a Skewness Value for the mesh elements. The element skewness is defined as:

Skewness = (V_reg - V_el) / V_reg

Where:

V_el is the volume of the element under calculation and V_reg is the volume of the standard tetrahedral linear element located in the same sphere as the element under calculation. When the element under calculation has an ideal shape (that of a standard tetrahedral element), V_reg = V_el and Skewness Value = 0.

When the element under calculation has the least ideal shape (that of a flat element), V_el = 0 and Skewness Value = 1.

Therefore, for the linear tetrahedral element, Skewness Value is always between 0 and 1, with 1 being a flat element. The default value is 0.9. The recommended Skewness Value is approximately 0.85 to 0.9.

When the Option property is set to Jacobian Ratio or Skewness and Jacobian Ratio, you need to enter a Jacobian Ratio Value for the mesh elements. This value defines the maximum Jacobian ratio at element integration points. The default value is 0.1.

Hex-Dominant

If the body selected in the scoping includes hexahedral mesh, then this category and its properties are applicable to solution processing. The application uses an initial hexahedral-dominant mesh which is converted to a tetrahedral mesh during the solution process once the category’s criterion is met. For a tetrahedral only mesh, application ignores this category and its properties. For this category:

The Options property is read-only and the application sets it to Shape.
The Maximum Corner Angle property has the default setting of 155°. The entry range for this property is 0° - 180°. An element is re-meshed when any of its corner angles reach this specified value.

Mesh (2D Analysis)

For 2D analyses:

The Options property is read-only and the application sets it to Shape.
The Maximum Corner Angle property has the default setting of 160° (recommended). The entry range for this property is 0° - 180°. An element is re-meshed when any of its corner angles reach this specified value.

All the following common criteria properties are available for all Criterion property options as well as 2D analyses:

Check At: Options included Equally Spaced Points or Specified Recurrence Rate.
Value: This property further defines the Check At property. The default value is 1.
Time Range: options included Entire Load Step or Manual. When specified as Manual, you need to enter a Start Time and End Time. The End Time value must be larger than the Start Time value.

Suppressed: Include (No - default) or exclude (Yes) the condition.