Transform Faces
Using the Transform Faces operation you can apply a linear transform (consisting of displacement, rotation, and isotropic scaling) on a selection of faces on 3D geometry objects. The transformed faces and their adjacent faces are extended or trimmed to cover any wounds that may result. Alternatively, the wounds are filled by inserting step faces.
To add a Transform Faces node to a geometry sequence, from the Geometry toolbar, Editing () menu, select Transform Faces(). You can also right-click the Geometry node and add this node from the context menu.
Enter the properties of the Transform Faces operation using the following sections:
Faces
Select the faces that you want to transform in the Graphics window. They then appear in the Faces to transform list. If the geometry sequence includes user-defined selections above the Transform Faces node, choose Manual to select faces, or choose one of the selection nodes from the list next to Faces to transform.
Click the Activate Selection button to toggle between turning ON and OFF the Faces to offset selections.
Select the Keep input objects checkbox if you want to use the selected geometry objects for further geometry operations.
Coordinate System
The coordinate system in which the point coordinates, displacements, and axis of rotation are interpreted for the linear transformation. From the Work plane list, select xy-plane (the default, for a standard global Cartesian coordinate system) or select any work plane defined above this node in the geometry sequence. If you choose a work plane, the work plane and its coordinate system appears in the Graphics window, using an extra coordinate triad with the directions xw, yw, and zw (which are then used to specify the coordinates, displacements, and the rotation axis position).
Center
Specify a point on the axis of rotation, and the centerpoint of the scaling by specifying x, y, and z; xw, yw, and zw if a work plane is selected as the coordinate system. This is the point that stays fixed during the scaling (that is, the point that the scaled faces approach when the scale factor goes to zero).
Rotation
From the Specify list, choose Axis of rotation (the default), Euler angles (Z-X-Z), or Edge as the way to specify the rotation.
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For Axis of rotation, select an Axis type: x-axis, y-axis, z-axis (the default), Cartesian, or Spherical. For any choice, enter an Angle (SI unit: degrees; default 0) to specify the rotation. If Cartesian is selected, enter Cartesian coordinates values for x, y, and z (default values 0, 0, and 1, respectively, corresponding to the global z-axis) to specify the axis vector. If Spherical is selected, specify the axis vector using spherical angles theta and phi in degrees (default: 90 and 0, respectively).
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For Euler angles (Z-X-Z), enter values for the intrinsic Z-X-Z Euler angles α, β, and γ in the corresponding text fields (in degrees; the default values are 0).
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For Edge, choose a straight edge as the axis of rotation and add it to the Straight edge list. Then enter an Angle (SI unit: degrees; default 0) to specify the rotation angle.
Scaling
Specify the isotropic scaling factor in the Factor field.
Displacement
Enter values or expressions to specify the x, y, and z displacements (SI unit: m).
Options
To decide how the step faces, which connect the bounding edges of the transformed faces with the adjacent faces, are created, select one of the available options for Create step faces:
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Select Yes to create step faces for all bounding edges of the transformed faces.
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Select Where faces meet with continuous tangent (default) to create step faces at all bounding edges where the selected faces meet the adjacent faces with tangent continuity.
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Select No to not create step faces.
When Create step faces is set to Yes you can select the checkbox Merge step faces with adjacent face, cleared by default, to extend and merge, if possible, the neighboring faces with the step faces.
When Create step faces is set to Where faces meet with continuous tangent you can select the checkbox Except if faces at ends of edge can be merged, cleared by default, to extend and merge, if possible, the neighboring faces at the two ends of those bounding edges where faces meet with continuous tangent.
Use the Overflow handling setting to determine how to handle the case when a transformed face moves beyond a nearby face in such a way that a wound (hole) appears. The following options are available:
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Automatic (default). The operation determines how to cover the wound caused by the overflow.
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Extend transformed faces. With this option the transformed faces are extended to cover the wound caused by the overflow.
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Extend other faces. With this option the faces that are not transformed are extended to cover the wound caused by the overflow.
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Cap faces. The wound caused by the overflow is covered by creating new faces based on the edges surrounding the wound.
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Disallow. This option will return an error message if overflow happens.
Selections of Resulting Entities
If you want to make the resulting entities contribute to a cumulative selection, select a cumulative selection from the Contribute to list (the default, None, gives no contribution), or click the New button to create a new cumulative selection (see Cumulative Selections in the COMSOL Multiphysics Reference Manual).
Select the Resulting objects selection checkbox to create predefined selections (for all levels — objects, domains, boundaries, edges, and points — that are applicable) in subsequent nodes in the geometry sequence. To also make all or one of the types of resulting entities (domains, boundaries, edges, and points) that the resulting objects consist of available as selections in all applicable selection lists (in physics and materials settings, for example), choose an option from the Show in physics list: All levels, Domain selection, Boundary selection, Edge selection, or Point selection. The default is Domain selection, which is suitable for use with materials and physics defined in domains. For use with a boundary condition, for example, choose Boundary selection. These selections do not appear as separate selection nodes in the model tree. Select Off to not make any selection available outside of the geometry sequence.
Selections on Input Objects
If you have Named Selections that include entities on the input objects, select the Propagate selections to resulting objects (selected by default) checkbox to update the selections to corresponding entities on the output objects, when possible. Clear the checkbox to not propagate the selection to the resulting objects. Selecting this option can be useful in combination with selecting the Keep input objects checkbox so that the selections refer only to the input objects.
Assigned Attributes
From the Construction geometry list choose On to make the resulting objects available only in the feature’s geometry sequence. The default option Inherit from input means that the resulting objects become construction geometry if all input objects are construction geometry. Choose Off to never output construction geometry objects. For more information see Construction Geometry in the COMSOL Multiphysics Reference Manual.