Application note: punching a sub-assy
AD2K2 provides with a tool which allows you to punch a shape in a surface.

This tool applies to a sub-assy. The punching process is based on a complex algorithm which is subject to some restrictions. The most stringent restriction is related to the punching shape which must be convex. Hopefully, you can always split a non-convex polygon into several triangles.

Let us take an example: we want to punch a gear well door in the lower part of a wing. The gear well door shape is made up of a circle and of a rectangle.

Let us create a WING sub-assy and then build the wing section and the shape.
                              
Sub-assy, New sub-assy name: WING
Template, New class Profile, 9 sides
name: WING
height: 9.0 ft - width: 2.4 ft
origin: x= 0.000   y= 0.000   z= 0.000
Template, New template height: 7.0 ft - width: 2.0 ft
origin: x= 12.000   y= 0.000   z= 0.000
Template, Cover template cover section
  select the Desk sub-assy
Draw, Shape, Circle (12) plane: top
center: x= 3.500   y= 3.900   z= 0.000
radius: 1.2 ft
Draw, Shape, Rectangle plane: top
center: x= 5.500   y= 3.900   z= 0.000
length: 1.4 ft   width: 3.0 ft

We just want to punch the intrados of the wing, don't we ? We need to split the wing into two parts: the extrados and the intrados. Let us create a sub-assy to home temporarily the intrados.
                              
Sub-assy, New sub-assy name: INTRA
  select the WING sub-assy
Sub-assy, Select chains..., bottom puts the bottom of the wing into the buffer
Selection, Move selection to sub-assy destination sub-assy: INTRA
  unselect the multiple selection mode

The punching process operates on a given sub-assy (called the sub-assy to punch) and stores the resulting triangles in a destination sub-assy. Let us create another temporary sub-assy (TEMP1) to punch the intrados with the circle.
                              
Sub-assy, New sub-assy name: TEMP1

Activate the Draw/Punch with chain menu option. An input panel is displayed on the right of the Graphic Editor window.

Select INTRA as the sub-assy to punch and TEMP1 as the destination sub-assy. Click on the Oz radio button to set the punching axis. Check the punch a hole and the cut a shape check-boxes. Select the circle by clicking on one of its vertices on the Graphic Editor display window. It is now drawn with a marroon color.

Validate the punching shape selection by clicking on the select punching shape OK button. Proceed by clicking on the OK button.

Tip: Be cautious not to click on the select punching shape OK button before you select the punching shape on the Graphic Editor window.

Tip: Nothing happens when you click on the OK button ? Are you sure you have selected the right punching axis ?

Activate the multiple selection mode. The punched part is stored into the multiple selection buffer. Create a GWELL sub-assy and move the multiple selection buffer into it.
                              
Sub-assy, New sub-assy name: GWELL
Selection, Move selection to sub-assy destination sub-assy: GWELL
  unselect the multiple selection mode
Have a look at the TEMP1 sub-assy: it is now featuring a hole in place of the circle.

We shall now punch the rectangle part of the gear well door. We need another temporary sub-assy, to be called TEMP2.
                              
Sub-assy, New sub-assy name: TEMP2

Activate the Draw/Punch with chain menu option. An input panel is displayed on the right of the Graphic Editor window.

Select TEMP1 as the sub-assy to punch and TEMP2 as the destination sub-assy. Click on the Oz radio button to set the punching axis. Check the punch a hole and the cut a shape check-boxes. Select the rectangle by clicking on one of its vertices on the Graphic Editor display window. It is now drawn with a marroon color.

Validate the punching shape selection by clicking on the select punching shape OK button. Proceed by clicking on the OK button.

Activate the multiple selection mode. The punched part is stored into the multiple selection buffer. Move it into the GWELL sub-assy.
                              
Selection, Move selection to sub-assy destination sub-assy: GWELL
  unselect the multiple selection mode
The whole gear well door is now stored into the GWELL sub-assy.

The punched intrados is stored into the TEMP2 sub-assy.

Tip: Uncheck the show hidden chains on the sub-assy panel to see the above figure.

We can now move the TEMP2 chains back into the WING sub-assy.
                              
  select the TEMP2 sub-assy
Sub-assy, Select all sub-assy chains selects the TEMP2 chains
Selection, Move selection to sub-assy destination sub-assy: WING

This is it ! Do not forget to delete the TEMP1, TEMP2 and INTRA sub-assies or to mark them as hidden otherwise they will appear when you display the model with FS.

Tip: The most common failure of the punching process occurs when a vertex of the punching shape coincide with a verrex of the sub-assy to punch when you look at them in the punching view.


copyright Hervé Devred 2003