Monday, March 10, 2008

Extremum and Polar Extremum Creation

Extremum and Polar Extremum Creation

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Path: Insert | Wireframe | Extremum
Insert | Wireframe | ExtremumPolar

clip_image002  Located in a fly-out on the Wireframe toolbar.

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Use this to ...

  • Create a point, line, or surface at the maximum or minimum position on a line, surface, or solid using direction or polar references.

Prerequisites

  • You should be in the Generative Shape Design workbench.
  • You must have the Generative Shape Design 2 product to use these commands.

Process: Creating an Extremum Point using Directional Reference

1. Select Insert | Wireframe | Extremum. The Extremum Definition dialog displays.

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2. In the Graphics window, pick the element that you want to create the extremum on, or select the element from the Specification Tree.

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3. Pick the first direction. CATIA enters the reference direction in the Direction box and creates the extremum.

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4. If required, pick the second direction. CATIA enters the reference direction in the Direction 2 box and modifies the extremum.

5. If required, pick the third direction. CATIA enters the reference direction in the Direction 3 box and modifies the extremum.

6. For each reference direction, activate the Max or Min option as required.

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7. Click OK to create the extremum.

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Process: Creating an Extremum Point using Polar References

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1. Select Insert | Wireframe | ExtremumPolar. The Polar Extremum Definition dialog displays.

2. In the Type list, select the required extremum.

3. In the Graphics window, pick the element that you want to create the extremum on, or select the element from the Specification Tree. CATIA enters the selected element in the Contour box.

4. Pick the support that the element lies on, or select the element from the Specification Tree. CATIA enters the selected element in the Support box.

5. In the Graphics window, pick the origin of the axis. CATIA enters the element as the Origin in the Axis area of the dialog.


6. As necessary pick a reference direction (in the case of Min or Max Angle). CATIA enters the element as the Reference direction in the Axis area of the dialog.

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7. Click OK to create the Extremum based off your axis and origin.

Options

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Extremum Reference Direction

Defines the direction that CATIA creates the extremum along. In general, CATIA creates a point extremum. However for some surfaces and solids, optional directional references are required. The following figure shows a solid where the X-axis is used as the reference direction. In this instance, the extremum is a surface and the four edges. When the Y direction is used as the optional reference direction, only one edge is the extremum. Selecting the Z-axis as the third optional direction results in a point extremum.

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Extremum Max and Min

Defines if the extremum is created at the maximum or minimum distance along the element, with respect to the reference direction and origin.

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Polar Extremum Type

Differs from the standard Extremum in that for Extremum you only define a direction, but for Polar Extremum you define an axis origin, as well as the reference direction. Within Polar Extremum, the four options available to the user are Min radius, Max radius, Min angle, and Max angle.

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Min Radius
Creates a point at the minimum distance from the reference axis origin to the picked element.

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Max Radius
Creates a point at the maximum distance from the reference axis origin to the picked element.

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Min Angle
Creates a point at the minimum angle from the reference axis origin and is measured from the reference direction.

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Max Angle
Creates a point at the maximum angle from the reference axis origin and is measured from the reference direction.

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Contour

Defines the set of curves or sketch on which the extremum is created. The contour must be planar and convex.

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Support

Defines the plane that the contour lies on. Even if the contour profile defines a plane the user must specify a support that the curves lie on. If a face is defined as the support then all of the contour must lie on the face.

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Axis

Defines the origin and orientation from which the extremum is measured.

Origin
Defines where the maximum and minimum radii and angles are measured from.

Reference Direction
Defines the direction that the maximum and minimum angles are measured from.

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Analysis

Displays the value of the radius or angle depending on your selection. Available with Polar Extremum only.


Radius
Displays the minimum or maximum radius when Min radius or Max radius is selected as the extremum type.

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Angle
Displays the minimum or maximum angle when Min angle or Max angle is selected as the extremum type.

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Tips

  • To quickly define the reference direction, right-click in the Reference direction box to access the directional pop-up menu.
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