WORKED EXAMPLE · HYPERBOLIC PARABOLOID, 400 MM ACROSS
Composite draping example: saddle
A 2D woven fabric cutting pattern generated from a 3D saddle using DrapeCut's pin-jointed net draping simulation. Warp at 0°, locking angle 45° (a 2×2 twill), seed placed by the tool. The part is a hyperbolic paraboloid, 400 mm across.
What this part shows
A saddle has negative Gaussian curvature: more surface at a given distance from the seed than a flat sheet has, not less. The tows still cannot stretch, so the crossings open the other way from the dome, and the lobes of the flat pattern are pulled in along the axes instead of out. The map looks similar in colour because shear angle is reported without sign, but the pattern is a different shape.
This is the case that a CAD flatten gets most wrong, because the surface has to be split to develop at all and the split has nothing to do with how cloth behaves. Max shear here is 17°; 0 cells are past the locking angle.
Open this example in DrapeCutChange the seed, the warp angle, the weave or the locking angle and the drape re-solves in well under a second. The DXF for an example downloads without an account.
How this page was made
The sample STL (19602 triangles) was draped by the same solver the tool runs, with these settings:
| Setting | Value |
|---|---|
| Warp direction | 0° |
| Tow pitch | 10 mm (coarse, so the net is legible; real cloth is 1–5 mm) |
| Locking angle | 45° |
| Seed | 0.7, -0.7, 0 mm (suggested by the tool) |
| Cells in the ply | 1764 |
Shear angle is pitch-independent to within the mesh resolution; cloth area and the flat size are quantised to the pitch.