There are two scenarios that may cause triangular plates:
· The surface itself is triangular
· The surface is trimmed to a triangular shape
When two corner control points have been compacted in Maxsurf a triangular surface has been created. Develop this surface by selecting “Add Surface Plate” from the plate menu.
As discussed in the “Adding a Plate” section, to be able to add a plate you first have to select four sides. If you have a trimmed surface which is triangular, one of the sides has zero length and this causes problems with the general development method. There are three different ways to develop this surface:
1. Use “Old developable” method
If you select the “Old Developable Method”, Workshop allows you to select the tip of the triangle by dragging the selection box around the point. This will be interpreted as a zero length side. After selecting the tip, you will be able to see a bold box at the edge indicating that it is selected.
2. Adding a contour line just before the tip of the triangle
Triangular plates may cause difficulties for the General plate development method. The fourth edge can be very small – just not infinitely short. It is normally possible to insert a section, waterline or buttock line or to use the surface parametric curves so that a very small fourth edge can be defined. For example:
The side plate of the skeg is a trimmed surface with a triangular contour shape.
Before adding a section just before the tip of the triangle it is good practise to display only the skeg side surface and only the required contours; in this case sections, intersections, edges and feature lines.
This looks like this:
By selecting four contours in the order as described in Adding a Plate on page 55 and selecting “add plate” from the plate menu, only one area of the surface is developed at a time.
Ø Add plate:
Ø Calculate the plate
Ø Do this for the entire plate:
Ø Until the section with the triangular tip is reached:
Because the final plate is a
triangle, it is impossible to select 4 sides. Workshop does not (yet) support
development of three, or n-sided plates.
Workshop needs the 4th side to be created before it can develop the plate. Do this by adding a section line in the grid spacing just before the tip of the triangle. That section line can then be used as the 4th side of the plate (even though it might be quite small).
Ø Add plate:
Ø Calculate plate:
The plate can be exported to AutoCAD and, if necessary, the plate edges can be extended so that the original Maxsurf surface is recreated. The stress/strain values and girth difference calculations will still be the same.
3. Develop the complete surface and use display intersection lines
See Developing Trimmed Surfaces on page 54