Creating a Drop-off

A drop-off can be defined by:

• a drop-off curve and a slope angle and a height.
  • The drop-off curve is the reference curve driving the drop-off. It must be parallel to the reference surface.
    This curve is the top or the bottom of the ramp, if identified.
  • The slope is the angle or drop-off ratio (e.g. 1:20) of the ramp with respect to the reference surface.
  • The height is the height of the bottom curve. This parameter is associated with the slope to create the bottom curve.
• or a drop-off curve and a bottom curve.
  In this case, Slope and Height are not required.
• a ply border: if the top drop-off curve does not exist, you must identify a ply border that will drive the drop-off. As a consequence an offset of (thickness at top – thickness at geometrical level x) is required as input as well as Slope and Height to compute the whole ramp from top to bottom.

If necessary, you can modify the limits of the drop-off:

• Start/End limits of drop-off curve: allow an extrapolation of the drop-off curve in order to generate a greater surface
• Left/Right limits: allow to re-limit the ramp surface in width and to position it along its width (particularly valued to a tolerance to avoid gaps while intersecting the ramp with the context surfaces)

Creating a Drop-Off with a Slope Angle

1. Click Drop-off  . The Drop-off dialog box is displayed.
   A graphic icon within the dialog box illustrates the parameters required.
   

2. Select Extrude.1 as the Reference surface. The dialog box is updated accordingly.

3. Select Extract.5 as the Drop-off curve.
   
   The Drop-off direction is displayed in the 3D view.
   Click Reverse, or the arrow in the 3D view, if the Drop-off direction is not correct.

4. Key in 1.5 as the Slope angle value.

5. Click Preview:
   

6. Click OK to validate and exit the dialog box.
   The drop-off is created:
   

Creating a Drop-Off from a Drop-Off Curve and a Bottom Curve

1. Close DropOffSA1.CATPart without saving it and re-open it.
   Recall Intersect.5 from the NoShow.

2. Click Drop-off . The Drop-off dialog box is displayed.
   A graphic icon within the dialog box illustrates the parameters required.
   

3. Select Extrude.1 as the Reference surface. The dialog box is updated accordingly.

4. Select Extract.5 as the Drop-off curve.
   

5. Select Intersect.5 as the Bottom curve.
   
   Slope and Height become inactive as they are no longer required to define the drop-off.
   
   Click Preview:
   

6. Click OK to validate and exit the dialog box.
   

Creating a Drop-off from a Ply Border

1. Open DropOffSA2.CATPart.

2. Click Drop-off . The Drop-off dialog box is displayed.
   A graphic icon within the dialog box illustrates the parameters required.
   

3. Select Extrude.1 as the Reference surface. The dialog box is updated accordingly.

4. Select a ply border as shown below as the drop-off curve:
   

5. The Drop-off direction and the Offset direction are displayed in the 3D view.
   
   If they are not correct, click the arrow to reverse it, or click Reverse in the dialog box.

6. Key in an Offset value (here 10.56) and select a bottom curve
   (or key in the Slope and Height values if the bottom curve does not exist).
   Click Preview.
   

7. Click OK to validate and exit the dialog box. The drop-off is created: