On this page:
4.2.1 Bottom-Up Geometry Creation
4.2.1.1 Creating Volumes
4.2.1.1.1 Sweep Surface Along Vector
4.2.1.1.2 Sweep Surface About Axis
4.2.1.1.3 Sweep Surface Along Curve
4.2.1.1.4 Sweep Surface Perpendicular
4.2.1.1.5 Sweep Surface to a Volume
4.2.1.1.6 Offset
4.2.1.1.7 Sheet Extended from Surface
4.2.1.1.8 Sweep Curve About Axis
4.2.1.1.9 Stitch Surfaces Together
4.2.1.1.10 Loft Surfaces Together
4.2.1.1.11 Thicken Surfaces
4.2.1.1.12 Sweeping a Surface to a Plane
4.2.1.1.13 Sweep Surface along a Direction
4.2.1.1.14 Sweep Surface along Helix
4.2.1.1.15 Volume Copy
4.2.1.2 Creating Curves
4.2.1.2.1 Straight
4.2.1.2.2 Parabolic, Circular, Ellipse
4.2.1.2.3 Spline
4.2.1.2.4 Copy
4.2.1.2.5 Combine Existing Curves
4.2.1.2.6 Arc Three
4.2.1.2.7 Arc End Vertices and Radius
4.2.1.2.8 Arc Center Vertex
4.2.1.2.9 Arc Center Angle
4.2.1.2.10 From Vertex Onto Curve
4.2.1.2.11 Offset
4.2.1.2.12 From Mesh Edge
4.2.1.2.13 Close To
4.2.1.2.14 Surface Intersection
4.2.1.2.15 By Projection
4.2.1.2.16 Creating a Helix
4.2.1.2.17 Tangents
4.2.1.2.18 Examples
4.2.1.3 Creating Surfaces
4.2.1.3.1 Bounding Curves
4.2.1.3.2 Bounding Vertices or Nodes
4.2.1.3.3 Copy
4.2.1.3.4 Extended Surface
4.2.1.3.5 Planar Surface
4.2.1.3.6 Net Surface
4.2.1.3.7 Offset
4.2.1.3.8 Skinning
4.2.1.3.9 Sweeping of Curves
4.2.1.3.10 Midsurface
4.2.1.3.11 Weld Profile
4.2.1.3.12 Creating A Surface From Mesh Entities
4.2.1.3.13 Creating a Circular Surface
4.2.1.3.14 Creating a Parallelogram
4.2.1.3.15 Creating an Ellipse
4.2.1.3.16 Creating a Rectangle
4.2.1.4 Creating Vertices
4.2.1.4.1 XYZ location
4.2.1.4.2 On Curve - Fraction
4.2.1.4.3 On Curve - General
4.2.1.4.4 From Vertex
4.2.1.4.5 At Arc
4.2.1.4.6 At Intersection
4.2.2 Geometric Primitives
4.2.2.2 Creating Bricks
4.2.2.3 Creating Frustums/  Cones
4.2.2.4 Creating Pyramids
4.2.2.5 Creating Toruses
4.2.2.6 Creating Cylinders
4.2.2.7 Creating Prisms
4.2.2.8 Creating Spheres
2021.11

4.2 Geometry Creation

There are three primary ways of creating geometry for meshing in Cubit. First, Cubit provides many geometry primitives for creating common shapes (spheres, bricks, etc.) which can then be modified and combined to build complex models. Secondly, geometry can be imported into Cubit. Finally, geometry can be defined by building it from the "bottom up", creating vertices, then curves from those vertices, etc. Two of these three methods for creating geometry in Cubit will be described in detail in this section.

All of these geometry creation commands have been expressed in the GUI’s command panels. To navigate to the volume creation command panels, for example, select "Mode-Geometry", then "Operation - Create Geometry", then "Entity-Create Volumes", as shown below. Other geometry creation command panels are available for each geometry type.

Figure 105:

4.2.1 Bottom-Up Geometry Creation

Cubit supports the ability to create geometry from a collection of lower order entities. This is accomplished by first creating vertices, connecting vertices with curves and connecting curves into surfaces. Currently only ACIS bodies or volumes may not be constructed by stitching a set of surfaces together, and only in a certain number of cases; however surfaces may also be swept or rotated to create bodies or volumes. Existing geometry may be combined with new geometry to create higher order entities. For example, a new surface can be created using a combination of new curves and curves already extant in the model. Commands and details for creating each type of geometry entity are given below.

4.2.1.1 Creating Volumes

Currently, Cubit can create volumes:

  1. from surfaces by sweeping a single surface into a 3D solid,

  2. by offsetting an existing volume,

  3. by extending one or more surfaces or sheet bodies

  4. by sweeping a curve around an axis,

  5. by stitching together surfaces that can form a closed volume,

  6. by lofting from one surface to another surface, or

  7. by thickening a surface body.

Sweeping of planar surfaces, belonging either to two- or three-dimensional bodies, is allowed, and some non-planar faces can be swept successfully, although not all are supported at this time.

There are five forms of the sweep command; the syntax and details for each are given below. Common options for first four forms are:

draft_angle: This parameter specifies the angle at which the lateral faces of the swept solid will be inclined to the sweep direction. It can also be described as the angle at which the profile expands or contracts as it is swept. The default value is 0.0.

draft_type: This parameter is an ACIS-related parameter and specifies what should be done to the corners of the swept solid when a non-zero draft angle is specified. A value of 0 is the default value and implies an extended treatment of the corners. A value of 1 is also valid and implies a rounded (blended) treatment of the corners.

anchor_entity: The default behavior for the sweep command is to move the source surface along a path to create a new 3D solid. The anchor_entity option instructs the sweep to leave the source surface in its original location.

include_mesh: This option will sweep the source surface and existing mesh into a meshed 3D solid. The mesh size is automatically computed using the Default auto interval specification.

The sweep operations have been designed to produce valid solids of positive volume, even though the underlying solid modeling kernel library that actually executes the operation, ACIS, allows the generation of solids of negative volume (i.e., voids) using a sweep.

4.2.1.1.1 Sweep Surface Along Vector

Sweeps a surface a specified distance along a specified vector. Specifying the distance of the sweep is optional; if this parameter is not provided, the face is swept a distance equal to the length of the specified vector. The include_mesh option will create a volumetric mesh if the surface is already meshed as shown below. The keep option will keep the original surface while creating the volume.

To sweep a Surface

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter the value for theSurface ID(s). This can also be done using the Pick Widget function.

  5. Click on Along Vector.

  6. Enter in the appropriate values for X, Y and Z.

  7. Enter in any other desired options from this menu.

  8. Click Apply.

Sweep Surface {<surface_id_range>} Vector <x_vector y_vector z_vector> [Distance <distance_value>] [switchside] [Draft_angle <degrees>] [Draft_type <0|1>][rigid][anchor_entity][include_mesh] [keep] [merge]

Figure 106: Surface mesh swept along a vector

4.2.1.1.2 Sweep Surface About Axis

Sweeps a surface about a specified vector or axis through a specified angle. The axis of revolution is specified using either a starting point and a vector, or by a coordinate axis. This axis must lie in the plane of the surfaces being swept. The steps parameter defaults to a value of 0 which creates a circular sweep path. If a positive, non-zero value (say, n) is specified, then the sweep path consists of a series of n linear segments, each subtending an angle of [( sweep_angle ) / ( steps-1 )] at the axis of revolution. The include_mesh option will create a volumetric mesh if the surface is already meshed as shown below. The keep option will keep the original surface while creating the volume.

To sweep a Surface About an Axis

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter the value for the Surface ID(s). This can also be done using the Pick Widget function.

  5. Click on About Axis.

  6. Select the appropriate Axis of Rotation.

  7. Enter in any other desired options from this menu.

  8. Click Apply.

Sweep Surface {<surface_id_range>} Axis {<xpoint ypoint zpoint xvector yvector zvector>|Xaxis|Yaxis|Zaxis} Angle <degrees> [switchside] [Steps <number_of_sweep_steps>] [Draft_angle <degrees>] [Draft_type <0|1>][rigid][anchor_entity][include_mesh] [keep] [merge]

Figure 107: Surface swept around an axis of 50 degree angle

Specifying multiple surfaces that belong to the same body will not work as expected, as ACIS performs the sweep operation in place. Hence, if a range of surfaces is provided, they ought to each belong to different bodies.

4.2.1.1.3 Sweep Surface Along Curve

This command allows the user to sweep a planar surface along a curve:

To sweep a Surface Along a Curve

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter the value for the Surface ID(s). This can also be done using the Pick Widget function.

  5. Click on Along Curve.

  6. Enter in the Curve ID.

  7. Select any other appropriate settings from this menu.

  8. Click Apply.

Sweep Surface <surface_id_range> Along Curve <curve_id> [Draft_angle <degrees>] [Draft_type <0 | 1 | 2>][rigid][anchor_entity][include_mesh] [keep] [individual] [merge]

One of the ends of the curve must fall in the plane of the surface and the curve cannot be tangential to the surface. Sweep along curve also supports an additional draft type "2" which implies a "natural" extension of the corners from their curves.

The include_mesh option will create a volumetric mesh if the surface is already meshed. The keep option will keep the original surface while creating the volume.

Figure 108: Volume generated by sweeping a surface along a reference curve

4.2.1.1.4 Sweep Surface Perpendicular

This command allows the user to sweep a planar surface perpendicular to the surface:

To sweep a Surface Perpendicular

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter the value for the Surface ID(s). This can also be done using the Pick Widget function.

  5. Click on Perpendicular.

  6. Enter in the desired Distance.

  7. Enter in any other appropriate settings from this menu.

  8. Click Apply.

Sweep Surface <surface_id_range> Perpendicular Distance <distance> [Switchside] [Draft_angle <degrees>] [Draft_type <integer>][anchor_entity][include_mesh] [keep] [merge]

The sweeping plane must be planar in order to determine the sweep direction. The switchside option will reverse the direction of the sweep.

Figure 109: The original surface is retained with the 'keep' option. A new volume is created by sweeping the surface along the surface normal.

The include_mesh option will create a volumetric mesh if the surface is already meshed. The keep option will keep the original surface while creating the volume.

4.2.1.1.5 Sweep Surface to a Volume

This command allows users to sweep a surface to a volume.

To sweep a Surface to a Volume

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter the value for the Surface ID(s). This can also be done using the Pick Widget function.

  5. Click on Target Volume.

  6. Enter in the appropriate values for Volume ID, Direction and Plane.

  7. Click Apply.

Sweep Surface <surface_id_range> Target {Volume|Body} <id> [Direction {options}] [Plane {options}]

The direction keyword can be used to control the direction of sweep. Without it, Cubit will determine the sweep direction (usually normal to the sweeping surface). The plane option can be used to define a stopping plane.

4.2.1.1.6 Offset

The following command creates a body offset from another body or set of surfaces at the specified distance. The new surfaces are extended or trimmed appropriately. A positive distance results in a larger body; a negative distance in a smaller body.

To create a Sheet Offset from a Surface

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click the Create action button.

  3. Select Offset from the drop-down menu.

  4. Enter in the appropriate values for From Surface ID(s) and Offset Value.

  5. Enter in any other desired settings from this menu.

  6. Click Apply.

Create Body Offset [From] Body <id_range> Distance <value>

Create Sheet Offset From Surface <id_list> Offset <val> [Surface <id_list> Offset <val>] [Surface <id_list> Offset <val> ...] [Preview]

Using the second form of the command, the sheet body can be created from a list of surfaces, and the surfaces may offset by different distances. This command currently requires the original surfaces to be on solid bodies.

This option is also available for limited cases for facet-based surfaces.

4.2.1.1.7 Sheet Extended from Surface

The following command creates a body offset from another body or set of surfaces at the specified distance. The new surfaces are extended or trimmed appropriately. A positive distance results in a larger body; a negative distance in a smaller body.

To create a Sheet Extended from a Surface.

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Extended Surface from the drop-down menu.

  4. Enter in the desired value for Surface ID(s).

  5. Enter in any other appropriate settings from this menu.

  6. Click Apply.

Create Sheet Extended From Surface <id_list> [Intersecting <entity_list>] [Extended {Percentage|Absolute} <val>] [Preview]

This command allows multiple surfaces to be extended at the same time. Optionally, you can give a list of bodies to intersect for this calculation. You can also extend the size of the surface by either a percentage distance or an absolute distance of the minimum area size. The plane can be previewed with the preview option. Figure 1 shows a set of surfaces being created using the extended absolute option.

Figure 110: Sheet created from extending multiple surfaces

4.2.1.1.8 Sweep Curve About Axis

Sweeps a curve or set of curves about a given axis through a specified angle. The axis is specified the same as in the Sweep Surface About Axis command. The steps, draft_angle, and draft_type options are the same as are described above. To create the solid, the make_solid option must be specified, otherwise a surface will be created, rather than a solid. If the rigid option is specified, then the curve or set of curves will remain oriented as originally oriented, rather than rotating about the axis.

To sweep a Curve about an Axis

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter in the value for the Curve ID(s). This can also be done using the Pick Widget function.

  5. Select Axis/Angle from the Sweep Method Menu.

  6. Enter in the appropriate Axis of Rotation.

  7. Enter in any other desired settings from this menu.

  8. Click Apply.

Sweep Curve <curve_id_range> {Axis <xpoint ypoint zpoint xvector yvector zvector>|Xaxis|Yaxis|Zaxis} Angle <degrees> [Steps <Number_of_sweep_steps>] [Draft_angle <degrees>] [Draft_type <integer>] [Make_solid] [Rigid]

4.2.1.1.9 Stitch Surfaces Together

A body can be created from various surfaces that form a closed volume with command below. The geometry must be ACIS-type geometry (i.e. imported from IGES, STEP or fastq files) This option is also available for limited cases for facet-based surfaces.

The heal option will attempt to close small gaps in the surface; the noheal option disables this behavior. The keep option preserves the original surfaces.

All of the surfaces must form a closed water-tight volume for this command to succeed unless the sheet option is specified. The sheet option allows for the creation of an open body.

To create a body with the Heal Option

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select From Bounding Surfaces from the drop-down menu.

  4. Enter the value for the Surface ID(s). This can also be done using the Pick Widget function.

  5. Select any other appropriate setting from this menu.

  6. Click Apply.

Create {Body|Volume} Surface <surface_id_range> [HEAL|Noheal] [Keep] [Sheet]

4.2.1.1.10 Loft Surfaces Together

A body can be "lofted" between two surfaces to form a new body. Surfaces from solid bodies and sheet bodies may be used to create a loft body. In order to create the loft body, two surfaces coincident to the input surfaces are created. The loft body is extruded along the shortest path between the corresponding vertices that define the shapes of the two copied surfaces. This new body is solid. The surfaces used to create the loft body are unchanged.

To loft Surfaces to create a Volume

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Lofted Volume from the drop-down menu.

  4. Enter the value for Surface ID(s). This can also be done using the Pick Widget function.

  5. Select an other appropriate settings from this menu.

  6. Click Apply.

Create {Body|Volume} Loft Surface <ids> [guide curve <id_list> [global_guides]] [Takeoff_factors <one value per surface in order>=.001] [Takeoff_vector Surface <id> {direction options}] [match vertex <ids>] [closed] [preview] [show_matching_curves]

Source surface ids must be specified in lofting order

Go to Location, Direction, and Axis Specification to see the direction command description.

The following options are available for lofting:

Lofting can be used to split a body in order to create a more structured mesh. Figure 2 below shows a single volume swept from a large paved surface. Figure 3 shows this same volume after surfaces defined on the source and target surfaces have been used to create a loft body. This original body was chopped with the loft body. The resulting two bodies were merged. The yellow volume was swept as the volume in Figure 2 was but the purple volume was submapped, producing a much more structured mesh overall.

Figure 111: Mesh before loft. Single swept volume with a large paved face.

Figure 112: Mesh after loft. The yellow volume is paved and the purple volume is submapped.

4.2.1.1.11 Thicken Surfaces

A surface body can be thickened to create a volume body. The surface can be thickened in both directions using the "both" keyword, thickened in the direction of surface normal using a positive depth, or thickened in the opposite direction using a negative depth. To thicken multiple surfaces, all surface normals must be consistent.

To thicken a Surface

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Modify Volumes action button.

  3. Select Thicken from the drop-down menu.

  4. Enter the appropriate values for Volumes ID(s) and Depth.

  5. To Thicken the volume in both direction, check the Thicken in both directions box.

  6. Click Apply.

Thicken [Volume|BODY] <id> Depth <depth> [Both]

4.2.1.1.12 Sweeping a Surface to a Plane

Sweeps a surface normal to a plane and towards the plane until the swept surface reaches the plane. See plane options for ways to describe a plane.

To sweep a Surface to a Plane

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter in the desired values for Surface ID(s) and Volume ID. This can also be done by using the Pick Widget function.

  5. Click on Target Volume.

  6. Click on Plane.... Another menu will appear.

  7. Enter in the appropriate settings.

  8. Click Apply. The menu will disapear leaving the selected settings in the Plane field.

  9. Enter in any other desired settings from this menu.

  10. Click on Apply.

Sweep surface <id> target plane <options>

4.2.1.1.13 Sweep Surface along a Direction

Sweep a surface along a direction to create a volume. See direction options for ways to specify a direction.

To sweep a Surface along a Direction

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Enter in the desired values for Surface ID(s). This can also be done using the Pick Widget function.

  5. Click on Direction from the Sweep Method menu.

  6. Click on the Direction... button. Another menu will appear.

  7. Enter in the appropriate settings.

  8. Click Apply. The menu will disapear leaving the selected settings in the Direction field.

  9. Enter in any other desired settings from this menu.

  10. Click Apply.

Sweep Surface <surface_id_range> Direction (options) [switchside] [draft_angle <degrees>] [draft_type <integer>] [rigid] [anchor_entity] [include_mesh] [keep] [merge]

Figure 113: Surface extruded along -X direction without 'include_mesh' option.

4.2.1.1.14 Sweep Surface along Helix

Sweep a surface along a helix, where the helix is defined by an axis, thread_distance (distance between turns in axis direction), axis, and handedness (right_handed or left_handed.

To sweep a Surface or Curve along a Helix

  1. On the Command Panel, click Geometry.

  2. To sweep a surface, click on Volume. To sweep a curve, click on Surface.

  3. Click on the Create action button.

  4. Select Sweep from the drop-down menu.

  5. Enter in the desired Surface or Curve ID(s). This can also be done using the Pick Widget function.

  6. Select Helix from the Sweep Method menu.

  7. Click the appriapte Axis from the Axis of Rotation menu.

  8. Enter in the appropriate values for Helix Height and Rotation Angle.

  9. Enter in any other desired settings

  10. Click Apply.

Sweep {Surface|Curve} <id_range> Helix {axis <xpoint ypoint zpoint xvector yvector zvector> | xaxis | yaxis | zaxis} thread_distance <val> angle <val> [RIGHT_HANDED|left_handed] [anchor_entity] [include_mesh] [keep] [merge]

Specifying multiple Surfaces that belong to the same Body can cause the creation of invalid Bodies and is discouraged.

axis = axis about which to create the sweep

thread_distance = distance between each 360 degree segment of the helix

angle = number of degrees in rotation of the helix

handedness = right-handed or left- handed threads

Figure 114: Helical Sweep

4.2.1.1.15 Volume Copy

Create a new volume by copying an existing volume. There are a number of commands to support this function. Below is the command panel which is accessed via Geometry/Volume/Create/Copy. Notice the opportunity to copy with various transforms, include the mesh from the source volume, and include boundary conditions from the source volume.

Figure 115:

4.2.1.2 Creating Curves

Curves are created by specifying the bounding lower-order topology (i.e. the vertices) and the geometry (shape) of the curve (along with any parameters necessary for that geometry).

4.2.1.2.1 Straight

The first form of the command creates a straight line or a line lying on the specified surface. If a surface is used, the curve will lie on that surface but will not be associated with the surface’s topology.

Create Curve [Vertex] <vertex_id> [Vertex] <vertex_id> [On Surface <surface_id>]

Straight curves can be created using an axis. The syntax is as follows:

Create Curve Axis {options}

The length of the axis must be specified. Go to Location, Direction, and Axis Specification to see the axis command description.

Additionally, several connected straight curves can be created with a single command. The syntax for the polyline command is as follows:

Create Curve Polyline Location {options} Location {options} ...

Notice that two or more locations are used to define a polyline. See Location, Direction, and Axis Specification for the location command description.

4.2.1.2.2 Parabolic, Circular, Ellipse

The parabolic option creates a parabolic arc which goes through the three vertices. The circular and ellipse options create circular and elliptical curves respectively that go through the first and last vertices.

Create Curve [Vertex <vertex_id> [Vertex] <vertex_id> [[Vertex] <vertex_id> [Parabolic|Circular|ELLIPSE [first angle <val=0> last angle <val=90>]]]

If ’ellipse’ is specified, Cubit will create an ellipse assuming the vectors between vertices (1 and 3) and (2 and 3) are orthogonal. v1-v3 and v2-v3 define the major and minor axes of the ellipse and v3 defines the center point. These vectors should be at 90 degrees. If not, Cubit will issue a warning indicating the vertices are not sufficient to create an ellipse and will then default to creating a spiral.

The angle options will specify what portion of the ellipse to create. If none are specified, first angle will default to 0 and last angle to 90 and the ellipse will go from vertex 1 to vertex 2; if the vertices are free vertices they will be consumed in the ellipse creation. First angle tells Cubit where to start the ellipse – the angle from the first axis (v1 - v3) specified. Last angle tells Cubit where to end the ellipse – the angle from the first axis. The angle follows the right-hand rule about the normal defined by (v1 - v3) X (v2 - v3).

4.2.1.2.3 Spline

The spline form of the command creates a spline curve that goes through all the input vertices or locations. To create a curve from a list of vertices use the syntax shown below. The delete option will remove all of the intermediate vertices used to create the spline leaving only the end vertices.

Create Curve [Vertex] <vertex_id_list> [Spline] [Delete]

Additionally, spline curves can be created by inputting a list of locations. Where the spline will pass through all of the specified locations. The syntax is shown below:

Create Curve Spline {List of locations}

See Location, Direction, and Axis Specification to view the location specification syntax.

4.2.1.2.4 Copy

This command actually copies the geometric definition in the specified curve to the newly created curve. The new curve is free floating.

Create Curve From Curve <curve_id>

For more copy options see the general copy command.

4.2.1.2.5 Combine Existing Curves

This command creates a new curve from a connected chain of existing ACIS curves.

Create Curve combine curve <id_list> [delete]

4.2.1.2.6 Arc Three

The following command creates an arc either through 3 vertices or tangent to 3 curves. The full qualifier will cause a complete circle to be created.

Create Curve Arc Three {Vertex|Curve} <id_list> [Full]

4.2.1.2.7 Arc End Vertices and Radius

The following command creates an arc using two vertices, the radius and a normal direction. The full qualifier will cause a complete circle to be created.

Create Curve Arc Vertex <id_list>
Radius <value> Normal {<x> <y> <z>} | {direction options} [Full]

Go to Location, Direction, and Axis Specification to see the direction command description.

4.2.1.2.8 Arc Center Vertex

The next form of the command creates an arc using the center of the arc and 2 points on the arc. The arc will always have a radius at a distance from the center to the first point, unless the radius value is given. Again, the full qualifier will cause a complete circle to be created.

Create Curve Arc Center Vertex <center_id> <end1_id> <end2_id>
[Radius <value>] [Full]
[Normal {<x> <y> <z>} | {direction options}]

Go to Location, Direction, and Axis Specification to see the direction command description.

Requires 3 Vertices - first is the center, the other two are the end points of the arc. A normal direction is required when the three points are colinear. Otherwise a normal direction is optional.

4.2.1.2.9 Arc Center Angle

This form of the command creates an arc using the center position of the arc, the radius, the normal direction and the sweep angle.

Create Curve Arc Center {<x=0> <y=0> <z=0>} | {location options}
Radius <value>
Normal {<x> <y> <z>} | {direction options}
Start Angle <value=0> Stop Angle <value=360>

Go to Location, Direction, and Axis Specification to see the location and direction command descriptions.

4.2.1.2.10 From Vertex Onto Curve

The following command will create a curve from a vertex onto a specified position along a curve. If none of the optional parameters are given, the location on the curve is calculated as using the shortest distance from the start vertex to the curve (i.e., the new curve will be normal to the existing curve).

Create Curve From Vertex <vertex_id> Onto Curve <curve_id> [Fraction <f> | Distance <d> | Position <xval><yval><zval> | Close_To Vertex <vertex_id> [[From] Vertex <vertex_id> (optional for ’Fraction’ & ’Distance’)]] [On Surface <surface_id>]

Default = Normal to the Curve

4.2.1.2.11 Offset

The next command creates curves offset at a specified distance from a planar chain of curves. The direction vector is only needed if a single straight curve is given. The offset curves are trimmed or extended so that no overlaps or gaps exist between them. If the curves need to be extended the extension type can be rounded like arcs, extended tangentially (the default -straight lines are extended as straight lines and arcs are extended as arcs), or extended naturally.

Create Curve Offset Curve <id_list> Distance <val> [Direction <x> <y> <z>] [Rounded|EXTENDED|Natural]

Direction is optional for offsets of individual straight curves only

In all cases, the specified vertices are not used directly but rather their positions are used to create new vertices.

4.2.1.2.12 From Mesh Edge

This commands creates a curve from an existing mesh given a starting node and an adjacent edge.

Create Curve From Mesh Node <id> Edge <id> [Length <val>]

The adjacent edge indicates which direction to propagate the curve.
The curve will be composed of mesh edges up to the specified length.
If no length is specified the curve will propagate as far as the boundary of the mesh. Figure 116 shows a example of a curve generated from the mesh.

Figure 116: Example of curve created from mesh

The underlying geometry kernel used for this command is Mesh-Based geometry. The new curve will also be meshed with the edges it was propagated through. A related command for assigning mesh edges directly to a mesh block is the Rebar command. See Element Block Specification for more details.

Full hexes or full tets must be used to propagate the curves through the interior of volume.

4.2.1.2.13 Close To

This option takes two geometric entities and creates the shortest possible curve between the two entities at the location where the two entities are the closest. The two entities may NOT intersect. If two vertices are given, the command will create a straight line between the two vertices.

Create Curve Close_To {Vertex|Curve|Surface|Volume|Body} <id_1> {Vertex|Curve|Surface|Volume|Body} <id_2>

4.2.1.2.14 Surface Intersection

The following commandcreates curvesat surface intersections.Multiple curves can be created from a single command.

Create Curve Intersecting Surface <id_list>

4.2.1.2.15 By Projection

The project command projects curves, or the curves of a surface another a single surface or multiple surfaces of a volume or body. The command syntax is as follows:}

Project {Curve <id_list> | Surface <id_list } Onto Surface <surface_id> [Imprint [Keepcurve] [Keepbody]] [Trim]

Project { Curve <id_list> | Surface <id_list> Onto {Body <id> | Volume <id>} [Target_surface <id_list>] [Imprint [Keepcurve] [Keepbody]]}

The first form of the command takes a list of curves or surfaces, and a projection surface. If a list of curves is given, the result will be the creation of a set of free curves on top of the projection surface. If a list of surfaces is given, the result will be the same as selecting the curves of the surface (i.e. a group of free curves on the projecting surface).

The second form will imprint the list of curves (or curves of the surface(s)) onto the surfaces of the specified bodies or volumes. The Target_surface option helps when the projection is ambiguous, for example projecting curves onto a thin-walled volume where the projection could be to either side, as shown in Figure 117.

Figure 117: Example of projecting curves to specific side of thin-walled volume

4.2.1.2.16 Creating a Helix

This command will create a helical curve. The command syntax is as follows:

Create Curve Helix { axis <xpoint ypoint zpoint xvector yvector zvector> | xaxis | yaxis | zaxis } location (options) thread_distance <value> angle <value> [RIGHT_HANDED | left_handed]

axis = axis about which to create the helix

location (options) = starting point of the helix

thread_distance = distance between each 360 degree segment of the helix

angle = number of degrees in rotation of the helix

handedness = right-handed or left- handed threads

4.2.1.2.17 Tangents

This command will create a spline curve by specifying the end points and the tangents at those points. The command syntax is as follows:

create curve tangent vertex <id> [direction (options)] vertex <id> [direction (options)]

create curve tangent location (options) direction (options) location (options) direction (options)

Both forms of the command can be broken into two parts: the starting point and ending point of the curve. The tangent direction is grouped with the associated point.

The first form of the command takes an existing vertex and an optional tangent direction. If the direction is not specified, it will be taken from the tangent at the endpoint of the connected curve. If the vertex is not connected to a curve, or it is connected to multiple curves, the direction must be specified. If the vertex is not connected to a curve, it will be incorporated into the new curve. Otherwise, a new vertex will be created for the new curve.

The second form of the command takes a location and a tangent direction. The directions must be specified and vertices will be created for the locations.

The two command forms can also be mixed. A curve can be created from an existing vertex and a specified location.

4.2.1.2.18 Examples

create curve tangent location 0 0 0 direction 1 0 0 location 1 1 0 direction 1 0 0

Figure 118: Create tangent curve with locations and tangent directions

create curve tangent vertex 1 vertex 3

merge vertex all

Figure 119: Create tangent curve by specifying vertices on curves. Tangents are extracted from the curve at the vertex location.

Go to Location, Direction, and Axis Specification to see the location and direction command description.

4.2.1.3 Creating Surfaces

There are two major ways to create surfaces in Cubit. First, surfaces can be created in Cubit by fitting an analytic or spline surface over a set of bounding curves. In this case, the curves must form a closed loop, and only one loop of curves may be supplied. The second method, is by sweeping a curve about an axis, along a vector, or along another curve. The result of these surface creation commands is a "sheet body" or a body that has zero measurable volume (it does however have a volume entity). This body may be decomposed with booleans and special webcutting commands or it may be used as a tool to decompose other bodies. Booleans can be used to cut holes out of these surfaces.

4.2.1.3.1 Bounding Curves

The first form of this command produces an analytic or spline surface fit to cover the bounding curves.

To create a Surface by Bounding Curves

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Bounding Curves from the drop-down menu.

  4. Enter in the appropriate values in the Curve ID(s) field. This can also be done using the Pick Widget function.

  5. Click Apply.

Create Surface Curve <curve_id_1> <curve_id_2> <curve_id_3>...

Another version of this command creates a surface from a set of bounding curves that all lie on one surface. If the curves are selected they must lie on the surface, and they must create a closed loop. The On Surface option forces the surface to match the geometry of the underlying surface exactly.

Bound Curves with On Surface option

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Bounding Curves from the drop-down menu.

  4. Click on the On Surface button.

  5. Enter in the appropriate values for Curve ID(s) and On Surface. This can also be done using the Pick Widget function.

  6. Click Apply.

Create Surface Curve <id_list> On Surface <surface_id>

4.2.1.3.2 Bounding Vertices or Nodes

The second form of this command uses vertices to fit an analytic spline surface. The On Surface option creates the surface from a set of nodes and vertices that all lie on one surface and restrains the surface to match the geometry of the underlying surface. The project option will project the nodes or vertices to the specified surface.

To create a Surface by bounding Vertices or Nodes

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Vertex List from the drop-down menu.

  4. Select Vertex or Node from the Select menu.

  5. Enter in the appropriate value for Vertex ID(s) or Node ID(s). This can also be done using the Pick Widget function.

  6. Click on the On Surface button and enter the appropriate value in for Surface ID.

  7. Click Apply.

Create Surface [Node|Vertex| <id_list> [On Surface <surface_id> {Project} ]

4.2.1.3.3 Copy

The next form creates a surface using the same geometric description of the specified surface. The new surface will be a stand-alone sheet body that is geometrically identical to the user supplied surface.

To create a Surface by making a Copy

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Copy from the drop-down menu.

  4. Enter in the appropriate value for Surface ID(s). This can also be done using the Pick Widget function.

  5. Click on Transform Copied Surfaces and select Move, Rotate, Reflect or Scale.

  6. Enter in the appropriate settings.

  7. Click Apply.

Create Surface From Surface <surface_id>

4.2.1.3.4 Extended Surface

The fourth form of the command creates a surface that is extended from a given surface or list of surfaces. The specified surface’s geometry is examined and extended out "infinitely" relative to the current model in Cubit (i.e. extended to just beyond the bounding box of the entire model). The given surfaces are extended as shown in the table.

To create a Surface by Extending a Surface

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Extended Surface from the drop-down menu.

  4. Enter in the appropriate value for Surface ID(s). This can also be done using the Pick Widget function.

  5. Enter in any other appropriate settings.

  6. Click Apply.

Create Surface Extended From Surface <surface_id>

Table 1. Surface Extension Results

Surface Type

Resulting Extended Surface

Spherical

Shell of Full Sphere

Planar

Plane of infinite size relative to model

Toroidal

Shell of Full Torus

Conical, cone, cylinder...

Shell of outside conic axially aligned with given conic of infinite height relative to model

Spline

Surface is extended to extents of the spline definition. This may not be any further than the surface itself, so caution should be used here.

Multiple surfaces can be offset at the same time to form a sheet body, by using the Create Sheet Extended from Surface command.

4.2.1.3.5 Planar Surface

The following commands create planar surfaces. The first passes a plane through 3 vertices, the second uses an existing plane, the third creates a plane normal to one of the global axes, and the fourth creates a plane normal to the tangent of a curve at a location along the curve. By default, the commands create the surface just large enough to intersect the bounding box of the entire model with minimum surface area. Optionally, you can give a list of bodies to intersect for this calculation. You can also extend the size of the surface by either a percentage distance or an absolute distance of the minimum area size. The plane can be previewed with the command Draw Plane [with]... (where the rest of the command is the same as that to create the surface).

To create a Planar Surface through 3 vertices

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Planar Surface from the drop-down menu.

  4. Select Vertex from the Create Planar Surface With Plane menu.

  5. Enter in the appropriate values for Vertex ID 1, 2 and 3. This can also be done using the Pick Widget function.

  6. Enter in any other appropriate settings from this menu.

  7. Click Apply.

Create Planar Surface [With] Plane Vertex <v1_id> [Vertex] <v2_id> [Vertex] <v3_id> [Intersecting] Body <id_range>] [Extended Percentage|Absolute <val>]

To create a Planar Surface using an Existing Plane

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Planar Surface from the drop-down menu.

  4. Select Surface from the Create Planar Surface With Plane menu.

  5. Enter in the appropriate value for Surface ID. This can also be done using the Pick Widget function.

  6. Enter in any other appropriate settings from this menu.

  7. Click Apply.

Create Planar Surface [With] Plane Surface <surface_id> [Intersecting] Body <id_range>] [Extended Percentage|Absolute <val>]

To create a Planar Surface normal to one of the global axes

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Planar Surface from the drop-down menu.

  4. Select XYZ from the Create Planar Surface With Plane menu.

  5. Select XY Plane, ZX Plane or YZ Plane from the select menu.

  6. Enter in the desired Offset Value.

  7. Enter in any other appropriate settings from this menu.

  8. Click Apply.

Create Planar Surface [With] Plane {Xplane|Yplane|Zplane} [Offset <val>] [Intersecting] Body <id_range>] [Extended Percentage|Absolute <val>]

To create a Planar Surface normal to curve

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Planar Surface from the drop-down menu.

  4. Select Normal To Curve from the Create Planar Surface With Plane menu.

  5. Enter in the appropriate Curve ID value. This can also be done using the Pick Widget function.

  6. Select Fraction, Distance, Position or Near Vertex from the Select menu.

  7. Enter in any other appropriate settings from this menu.

  8. Click Apply.

Create Planar Surface [With] Plane Normal To Curve <curve_id>{Fraction <f>| Distance <d> | Position <xval><yval><zval> | Close_to vertex <vertex_id>} [[From] Vertex <vertex_id> (optional for ’fraction’ & ’distance’)] [Intersecting] Body <id_range>] [Extended Percentage|Absolute <val>]

4.2.1.3.6 Net Surface

Net surfaces can be created with two different commands. A net surface passes through a set of curves in the u-direction and a set of curves in the v-direction (these u and v curves would looked like a mapped mesh). The first form of the command uses curves to create the net surface. The curves must pass within tolerance of each other to work. The second form uses a mapped mesh to create the surface. The mapped mesh can be of a single surface or a collection of mapped or submapped surfaces that form a logical rectangle. By default net surfaces are healed to take advantage of any possible internal simplification.

To create a Net Surface from UV curves

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Net Surface from the drop-down menu.

  4. Select From UV Curve from the select menu.

  5. Enter in the appropriate values for U Curve ID(s) and V Curve ID(s). This can also be done using the Pick Widget function.

  6. Enter in any other appropriate settings from this menu.

  7. Click Apply.

Create Surface Net U Curve <id_list> V Curve <id_list> [Tolerance <value>] [HEAL|Noheal]

To create a Net Surface from Mapped Surface

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Net Surface from the drop-down menu.

  4. Select Mapped Surface from the select menu.

  5. Enter in the appropriate value for Surface ID(s). This can also be done using the Pick Widget function. The surface must be meshed.

  6. Enter in any other appropriate settings from this menu.

  7. Click Apply.

Create Surface Net [From] [Mapped] Surface <id_list> [Tolerance <value>] [HEAL|Noheal]

A suggested geometry cleanup method is to use a virtual composite surface to map mesh a set of complicated surfaces then create a net surface from this mesh. Then the original surfaces can be removed with the noextend option and the new net surface combined back onto the body.

4.2.1.3.7 Offset

The following command creates surfaces offset from existing surfaces at the specified distances.

To create a Surface offset from an Existing Surface

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Offset from the drop-down menu.

  4. Enter in the appropriate value for From Surface ID(s). This can also be done using the Pick Widget function.

  5. Enter in the appropriate value for Offset Value.

  6. Enter in any other approrpriate settings from this menu.

  7. Click Apply.

Create Surface Offset [From] Surface <id_list> Distance <val>

The surface offset command will only translate the existing surfaces, without extending or trimming them. An alternate form of the command for sheet bodies will maintain connections between surface by extending or trimming as they are offset, shown in Figure 120. On the left, the surfaces are offset using the surface offset command. On the left, the surface is created by using the "sheet" version of the command.

Figure 120: Offsetting surfaces to form individual surfaces or sheet bodies

4.2.1.3.8 Skinning

The following command creates a skin surface from a list of curves. An example of a skin surface is to create a surface through a set of parallel lines.

To create a Surface by Skinning

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Skin Curve from the drop-down menu.

  4. Enter in the appropriate values for Curve ID(s). This can also be done using the Pick Widget function.

  5. Click Apply.

Create Surface Skin Curve <id_list>

4.2.1.3.9 Sweeping of Curves

A curve or a set of curves can be swept along a path to create new surfaces. The path may be specified as an axis and angle, a vector and distance, by indicating another curve or set of contiguous curves, or by specifying a target plane. The following commands show the options available:

To sweep a Curve along an Axis

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Select Axis/Angle from the Sweep Method menu.

  5. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.

  6. Select the appropriate Axis from the Axis of Rotation menu.

  7. Enter in the appropriate values for Angle and Steps.

  8. Enter in any other appropriate settings from this menu.

  9. Click Apply.

Sweep Curve <curve_id_range> { Axis <xpoint ypoint zpoint xvector yvector zvector> | Xaxis | Yaxis | Zaxis } Angle <degrees> [Steps <Number_of_sweep_steps>] [Draft_angle <degrees>] [Draft_type <integer>] [Make_solid] [Include_mesh] [Keep][Rigid]

To sweep a Curve using a Vector

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Select Vector and Distance from the Sweep Method menu.

  5. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.

  6. Enter in the appropriate values in the Vector X,Y,Z field.

  7. Enter in any other appropriate settings from this menu.

  8. Click Apply.

Sweep Curve <curve_id_range> Vector <xvector yvector zvector> [Distance <distance>] [Draft_angle <degrees>] [Draft_type <integer>] [Include_mesh] [Keep] [Rigid]

To sweep a Curve along Curve

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Select Along Curve from the Sweep Method menu.

  5. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.

  6. Enter in any other appropriate settings from this menu.

  7. Click Apply.

Sweep Curve <curve_id_range> Along Curve <refcurve_id_range> [Draft_angle <degrees>] [Draft_type <integer>] [Include_mesh] [Keep] [Rigid]

To sweep a Curve using a Target Volume

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Sweep from the drop-down menu.

  4. Select Target Volume from the Sweep Method menu.

  5. Enter in the appropriate values for Volume ID and Curve ID(s). This can also be done using the Pick Widget function.

  6. Enter in the appropriate settings for Direction. Click on the Direction... button to open a separate window to specify settings.

  7. Enter in the appropriate settings for Plane. Click on the Plane... button to open a separate window to specify settings.

  8. Click Apply.

Sweep Curve <curve_id_range> Target Plane <options>

Sweep Curve <curve_id_range> Target {Volume|Body} <id> Direction {options} [Plane <options>] [Unite]

In the first command, the steps options provides a way of faceting the sweep, so instead of a smooth round sweep, there are facets to the surface. The make_solid option closes the newly-created surface to the axis, so that a solid is created instead of a surface.

In the above commands, the include_mesh option will create a surface mesh if the curve is already meshed (see figure below). The keep option will keep the original curve while creating the surface.

Figure 121:

The sweep curve target plane command sweeps a curve until it hits a target plane. The options for the target plane are described under Specifying a Plane.

The last command sweeps a curve to a target volume or body and can only be used on sheet bodies. Use the direction keyword to specify the sweep direction and the plane keyword to specify a stopping plane. The unite keyword will unite the sheet bodies after sweeping

The other options are as follows:

draft_angle: determines how much drafting in of the surface is desired

draft_type:

0 => extended (draws two straight tangent lines from the ends of each segment until they intersect)

1 => rounded (create rounded corner between segments)

2 => natural (extends the shapes along their natural curve)

rigid: normally the curve will rotate to maintain its original orientation to the sweep path. The rigid option disallows this rotation.

4.2.1.3.10 Midsurface

Multisurfaces may be created midway between pairs of surfaces using the following command:

To create a Surface midway between pairs

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Midsurface from the drop-down menu.

  4. Enter the appropriate values for Volume ID and Surface ID Pairs. This can also be done using the Pick Widget function.

  5. Click Apply.

Create Midsurface {Body|Volume} <id> Surface <id11> <id12> ... <idN1> <idN2>

where N denotes the number of pairs of surfaces. An even number of surfaces must be specified, and the command will group them by pairs in the order in which they are provided. The resulting surface will be trimmed by the specified body or volume <id>. This replaces the create midplane command in previous versions of Cubit.

Figure 122: Multisurface created with the Create Midsurface command

Figure 123: Midsurface created from 2 pairs of cylindrical surfaces

Midsufaces can also be extracted without surface pair specification if the resulting surface is a single sheet of surfaces (no T intersections).

For automatic midsurface extraction

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Auto Midsurface from the drop-down menu.

  4. Enter the appropriate values for Volume ID(s). This can also be done using the Pick Widget function.

  5. Enter the appropriate values for Lower Bounds and Upper Bounds.

  6. Enter in any other appropriate settings from this menu.

Create Midsurface {Body|Volume} <id_range> Auto [Delete] [Transparent] [Thickness] [Limit <lower_bound> <upper_bound>] [Preview]

Figure 124 shows a simple auto midsurface example. The command for the example is:

create midsurface volume 1 auto delete

Figure 124: Midsurface created from a volume

The command option descriptions are listed below.

auto enables the automatic mid-surface algorithm. Turning Auto off requires the user to specify a single surface pair to create a mid-surface.

transparent shows the successfully midsurfaced volumes as transparent in the graphics display

thickness applies a 2D property to the created mid-surface geometry.

limit search range gives the algorithm a range to find surface pairs within.

4.2.1.3.11 Weld Profile

Surfaces may be created by specifying a weld profile using the following command:

Create Surface Weld [Root] Location {options} Weld Surface <id_list> Length <val> [<val2>]

Weld surfaces can be used to create a simulated welded joint by sweeping the surface along the root curve and uniting the new body to the model. An example of the command is illustrated below. For a detailed description of the location specifier see Location Direction, and Axis Specification.

create surface weld root location vertex 25 weld surface 13 14 length 2

Figure 125: Weld Profile surface with length and root specifications

4.2.1.3.12 Creating A Surface From Mesh Entities

Surfaces may be created from the boundaries of meshed volumes, surfaces, and/or from individual quadrilateral mesh elements. The individual option makes it so you can enter multiple surfaces at once, and not have them merged together into a larger surface, but instead retain their own original boundaries. The optional tolerance value allows the user to specify a tolerance to which the resulting surface should be fit. The default value is 0.001. If surface creation fails, increasing the tolerance value can help.

Create Acis [From] {Surface <id_range> | Volume <id_range> | Face < id_range> [Individual]} [Tolerance <value>]

Figure 126: Acis Surface created from a Set of Quadrilaterals

4.2.1.3.13 Creating a Circular Surface

This command creates a 2D circular surface. The surface will be centered at the origin and on the z-plane if a plane option is not specified.

To create a Cirular Surface using a radius

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Circle from the drop-down menu.

  4. Select Radius from the Specify Circle Using menu.

  5. Enter in the appropriate Radius value.

  6. Select XPlane, YPlane or ZPlane.

  7. Click Apply.

create surface circle radius <value> {xplane|yplane|ZPLANE}

This command creates a 2D circular surface by specifying three vertices;the first vertex will be the center of the surface, the second vertex will be used to define the radius of the surface, and the third vertex will assist in defining the plane that the surface will lie in.

To create a 2D circular surface by specifying three vertices

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Circle from the drop-down menu.

  4. Select Center Vertex from the Specify Circle Using menu.

  5. Enter in the appropriate values for Center, Vertex 1 and Vertex 2. This can also be done using the Pick Widget function.

  6. Click Apply.

create surface circle center vertex <v1_id> <v2_id> <v3_id>

This command creates a 2D circular surface by forming a circular curve through three points.

To create a 2D circular surface by forming a circular curve through three points.

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Circle from the drop-down menu.

  4. Select Vertex List from the Specify Circle Using menu.

  5. Enter in the appropriate values for Vertex 1, Vertex 2 and Vertex 3. This can also be done using the Pick Widget function.

  6. Click Apply.

create surface circle vertex <v1_id> <v2_id> <v3_id>

4.2.1.3.14 Creating a Parallelogram

This command creates a 2D parallelogram surface, centered at the origin, by specifying three corner vertices.These vertices will form three consecutive corners of the parallelogram surface.

To create a 2D parallelogram surface

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Parallelogram from the drop-down menu.

  4. Enter in the appropriate values for Vertex 1, Vertex 2 and Vertex 3. This can also be done using the Pick Widget function.

  5. Click Apply.

create surface parallelogram vertex <v1_id> v2_<id> <v3_id>

4.2.1.3.15 Creating an Ellipse

This command creates a 2D elliptical surface, centered at the origin, by specifying at least a major radius.On an x-y plane this radius will be the radius along the x-direction.The minor radius will be the radius along the y-direction.By default, the surface will lie in the z-plane.

To create a 2D elliptical surface

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Ellipse from the drop-down menu.

  4. Select Radius from the Specify Ellipse Using menu.

  5. Enter in the appropriate values for Major Radius and Minor Radius.

  6. Select XPlane, YPlane or ZPlane.

  7. Click Apply.

Create Surface Ellipse major radius <value> [minor radius <value>] [xplane|yplane|ZPLANE]

This command creates a 2D elliptical surface using three vertices.The first two vertices define the major and minor radii of the ellipse surface.The third point defines the center of the ellipse.It is important to note that a line from v1_id to v3_id must be orthogonal to a line from v2_id to v3_id, otherwise the command will fail.

To create a 2D elliptical surface using three vertices

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Ellipse from the drop-down menu.

  4. Select Vertex List from the Specify Ellipse Using menu.

  5. Enter in the appropriate values for Axis 1 Vertex ID, Axis 2 Vertex ID and Origin Vertex ID. This can also be done using the Pick Widget function.

  6. Click Apply.

Create Surface Ellipse vertex <v1_id> <v2_id> <v3_id>

4.2.1.3.16 Creating a Rectangle

This command creates a rectangular surface centered at the origin.If only a width value is specified, the surface will be a square.On an x-y plane, the width value is the x-direction and the height is the y-direction.By default, the surface will lie in the z-plane.

To create a rectangular surface centered at the origin

  1. On the Command Panel, click on Geometry and then Surface.

  2. Click on the Create action button.

  3. Select Rectangle from the drop-down menu.

  4. Enter in the appropriate values for Width and Height (Optional).

  5. Select XPlane, YPlane or ZPlane.

  6. Click Apply.

Create Surface rectangle width <value> [height <value>] [xplane|yplane|ZPLANE]

4.2.1.4 Creating Vertices

The basic commands available for creating new vertices directly in Cubit are detailed in this section.

4.2.1.4.1 XYZ location

The simplest form of this command is to specify the XYZ location of the vertex. It can also be created lying on a curve or surface in the geometric model by specifying the curve or surface id; the position of the vertex will be the point on the specified entity which is closest to the position specified on the command. With all of these commands, the user is able to specify the color of the vertex.

To create a Vertex by specifying the XYZ location

  1. On the Command Panel, click on Geometry and then Vertex.

  2. Click on the Create action button.

  3. Select Coordinates from the drop-down menu.

  4. Enter in the appropriate values for X Coordinate, Y Coordinate and Z Coordinate.

  5. Select Curve or Surface from the Create On menu.

  6. Enter in the appropriate values for Curve ID or Surface ID. This can also be done using the Pick Widget function.

  7. Optionally, specify the color.

  8. Click Apply.

Create Vertex <x><y><z> [On [Curve | Surface] <id>] [Color <color_name>]

4.2.1.4.2 On Curve - Fraction

A vertex can be positioned a certain fraction of the arc length along a curve using the second form of the command.

To create a Vertex from the On Curve options

  1. On the Command Panel, click on Geometry and then Vertex.

  2. Click on the Create action button.

  3. Select On Curve from the drop-down menu.

  4. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.

  5. Select Fraction, Distance, Position, Close to Vertex, Segments or Midpoint from the Specify Location menu.

  6. Enter in the remaining appropriate information for this menu.

  7. Optionally, specify the color.

  8. Click Apply.

Fraction: Divides the selected curve into segments based on the fraction value entered and creates a vertex at the end of the first segment. Specify from which direction by seleting Start, End or Vertex. For example, create a vertex at .25 (1/4) the length of a curve.

Distance: Creates a vertex on the selected curve the specified number of units away from the starting point (start, end, vertex, curve and surface). For example, create a vertex a distance of 2 along a curve with length 5.

Position: Creates a vertex at the location entered into the X,Y and Z coordinates.

Close to Vertex: Creates a vertex on the selected curve at the closest point to a specified vertex.

Segments: Divides the selected curve into a specified number of segments and creates a vertex at each endpoint.

Midpoint: Creates a vertex at the Midpoint of the selected curve.

Vertex 3 in the following example was created with this command:

create vertex on curve 1 fraction 0.25 from vertex 1

Figure 127: Create Vertex a Fraction of the length of a Curve

4.2.1.4.3 On Curve - General

A more general purpose form of the command is also available for creating vertices on curves:

Create Vertex On Curve <id_list> { MIDPOINT | Start | End | Fraction <val 0.0 to 1.0> [From Vertex <id> | Start|End] | Distance <val> [From {Vertex|Curve|Surface} <id> | Start|End] | {{Close_To|At} Location {options} | Position <xval><yval><zval>|{Node|Vertex} <id>} | Extrema [Direction] {options} [Direction {options}] [Direction {options}] | Segment <num_segs> | Crossing {Curve|Surface} <id_list> [Bounded|Near] } [Color <color_name>]

It allows the vertex to be created at a fractional distance along the curve, at an actual distance from one of the curves ends, at the closest location to an xyz position or another vertex, or at a specified distance from a vertex, curve or surface. You can also preview the location first with the command Draw Location On Curve (where the rest of the command is identical to the Create Vertex form).

4.2.1.4.4 From Vertex

Create a vertex from an existing vertex.

Create Vertex from Vertex <id_list> [ On {Curve|Surface} <id> ] [Color <color_name>]

If ’on curve|surface’ option is used, the vertex is positioned on that curve or surface. When the ’on curve|surface’ is not used, the new vertex is positioned on the existing vertex.

4.2.1.4.5 At Arc

Another form simply creates vertices at arc or circle centers.

To create a Vertex in the Center of an Arc

  1. On the Command Panel, click on Geometry and then Vertex.

  2. Click on the Create action button.

  3. Select Arc Center from the drop-down menu.

  4. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.

  5. Optionally, specify the color.

  6. Click Apply.

Create Vertex Center Curve <id_list> [Color <color_name>]

4.2.1.4.6 At Intersection

The last form creates vertices at the intersection of two curves. If the bounded qualifier is used, the vertices are limited to lie on the curves, otherwise the extensions of the curves are also used to calculate the intersections. The near option is only valid for straight lines, where the closest point on each curve is created if they do not actually intersect (resulting in two new vertices).

To create a Vertex at an Intersection

  1. On the Command Panel, click on Geometry and then Vertex.

  2. Click on the Create action button.

  3. Select At Intersection from the drop-down menu.

  4. Enter in the appropriate values for Curve ID 1 and Curve ID 2. This can also be done using the Pick Widget function.

  5. Enter in any other appropriate settings from this menu.

  6. Optionally, specify the color.

  7. Click Apply.

Create Vertex AtIntersection Curve <id1> <id2> [Bounded] [Near] [Color <color_name>]

4.2.2 Geometric Primitives

The geometric primitives supported within Cubit are pre-defined templates of three-dimensional geometric shapes. Users can create specific instances of these shapes by providing values to the parameters associated with the chosen primitive. Primitives available in Cubit include the brick, cylinder, torus, prism, frustum, pyramid, and sphere. Each primitive, along with the command used to generate it and the parameters associated with it, are described next. For some primitives, several options can be used to generate them, and are described as well.

4.2.2.1 General Notes
4.2.2.2 Creating Bricks

Figure 128:

The brick is a rectangular parallelepiped. A cubical brick is created by specifying only the width or x dimension.

To create a Brick

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Brick from the drop-down menu.

  4. Enter in the desired values for the Brick Dimensions.

  5. Click Apply.

A brick can be specified to occupy the bounding box of one or more entities, specified on the command line.

To create a Bounding Box

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Bounding Box from the drop-down menu.

  4. Select the volume to be bounded.

  5. Enter the appropriate settings.

  6. Click Apply.

If the Tight option is specified with Bounding Box, the result is the smallest brick that can contain the entities specified, which is the default behavior of the Bounding Box option.

If the Extended option is specified with Bounding Box, the result is a brick that is extended from a "tight" brick by the input percentage or absolute value.

If a bounding box specification is used in conjunction with any of the other parameters (X, Y or Z), the parameters specified override the bounding box results for that or those dimensions.

[Create] Brick {Width|X} <width> [{Depth|Y} <depth>] [{Height|Z} <height>] [Bounding Box {entity_type} <id_range>] [Tight] [[Extended] {Percentage| Absolute} <val>]]

4.2.2.3 Creating Frustums/Cones

Figure 129:

A frustum is a general right elliptical cone with a top radius greater than 0.

To create a Cone or Frustum

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Cone from the drop-down menu.

  4. Enter in the desired values for Height, Top Radius and Radius.

  5. Select Cirular or Elliptical.

  6. Click Apply.

[Create] Frustum [Height|Z] <z-height> Radius <x-radius> [Top <top_radius>]

[Create] Frustum [Height|Z] <z-height> Major Radius <radius> Minor Radius <radius> [Top <top_radius>]

4.2.2.4 Creating Pyramids

Figure 130:

A pyramid is a general n-sided prism.

To create a Pyramid

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Pyramid from the drop-down menu.

  4. Enter the desired values for Height, Number of Sides and Top Radius.

  5. Select Circular or Elliptical.

  6. Enter the desired value for the Radius.

  7. Click Apply.

[Create] Pyramid [Height|Z] <z-height> Sides <nsides> Radius <radius> [Top <top-x-radius>]

[Create] Pyramid [Height|Z] <z-height> Sides <nsides> [Major [Radius] <x-radius> Minor [Radius] <y-radius> ] [Top <top-x-radius>]

4.2.2.5 Creating Toruses

Figure 131:

The torus command generates a simple torus

To create a Torus

  1. On the Command Planel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Torus from the drop-down menu.

  4. Enter the desired values for Major Radius and the Minor Radius.

  5. Click Apply.

[Create] Torus Major [Radius] <major-radius> Minor [Radius] <minor-radius>

4.2.2.6 Creating Cylinders

Figure 132:

The cylinder is a constant radius tube with right circular ends.

To create a Cylinder

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Cylinder from the drop-down menu.

  4. Enter in the desired values for Height and Radius.

  5. Select Circular or Elliptical.

  6. Click Apply.

[Create] Cylinder [Height|Z] <val> Radius <val>

[Create] Cylinder [Height|Z] <val> Major Radius <val> Minor Radius <val>

4.2.2.7 Creating Prisms

Figure 133:

The prism is an n-sided, constant radius tube with n-sided planar faces on the ends of the tube.

To create a Prism

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Prism from the drop-down menu.

  4. Enter in the desired values for Height, Number of Sides and Radius.

  5. Select Circular or Elliptical.

  6. Click Apply.

[Create] Prism [Height|Z] <z-val> Sides <nsides> Radius <radius>

4.2.2.8 Creating Spheres

Figure 134:

The sphere command generates a simple sphere, or, optionally, a portion of a sphere or an annular sphere.

To create a Sphere

  1. On the Command Panel, click on Geometry and then Volume.

  2. Click on the Create action button.

  3. Select Sphere from the drop-down menu.

  4. Enter the desired value for the Radius.

  5. Fill out any other desired values or options on the menu.

  6. Click Apply.

[Create] Sphere Radius <radius> [Xpositive]|[Xnegative] [Ypositive]|[Ynegative] [Zpositive]|[Znegative] [Delete] [Inner [Radius] <radius>]