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Cylindrically Symmetric 2D Models
A number of features speed conversion of 2D models with cylindrical symmetry.
is a cross section of a pulley consisting of lines and arcs. The blue lines are a detail layer and can be hidden. In the 2D CAD selection mode (entered by 2D Selection in the CAD Objects submenu of the Graphics menu or the Select Curve button on the CAD 2D Surfaces property page), the curve closest to the cursor is drawn in blue as shown below.
A right click shows a menu containing conversion options for the curve. In addition to a plane, a line can be used to make a cylinder, cone, RCC, or TRC. These objects require the existence of another line with matching coordinates at each end in one direction and of the opposite slope. If the slope is 0, a cylinder or RCC is made. Otherwise, the object is a cone or TRC. For the body choices, the height is the length of the line in the direction of the axis. Similarly, a circle or arc can define a torus if a matching circle or arc is found.
More than one match is possible. The blue line in the above Figure can be paired in both the X and Y directions, as can the arcs that form the rounded corners. To remove the ambiguity, the direction of the symmetry axis can be specified on the CAD Objects property page (X in the case of the pulley model).
Most of the geometry can be converted using the items in the context menu. If bodies are chosen and the option to make cells from new bodies active (Make Cells checked in the Options submenu of the Bodies menu), most cells will be defined. The remaining pulley cells not defined are in the region above and below the arcs. Five additional surfaces are required: 2 planes from the vertical lines contiguous with the arcs, 2 tori made from the arcs, and a CX cylinder passing through the bottom of the top arcs (middle horizontal line in the Figure below).
To define the remaining cells, the surfaces bounding the existing bodies need to be visible and thus pickable—check Draw Body Surfaces in the Options submenu of the Bodies menu. Four cells (gold and gray in the above Figure) can then be made using these surfaces
shows the converted geometry. Most of the volume outside of the pulley can be constructed by defining RCCs using the largest cylinder and the planes of the interior RCCs and TRCs and defining cells from the outer body minus the inner body. Future versions of Moritz will contain an algorithm to automate most of the steps described above for cylindrically symmetric models.
 White Rock Science http://www.whiterockscience.com/wrs.html 505 672 1105 |
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