Hi Eva,
Here’s a small modification of your file-
curved hinge - w.gh (22.2 KB)
For curved crease folding, the mesh edges which are not creases also need a hinge applied with zero rest angle, to give those parts of the paper bending resistance, so they bend instead of crumple.
If you know in advance the ruling directions it will bend along, you can also divide the surface into quads and keep those quads planar, and then it can form a single degree of freedom system so the additional bending resistance might not be needed.
Knowing these ruling directions isn’t always easy though, and for some origami they even need to change during the folding, which makes the planar quad approach unsuitable.
Here’s another example of a different approach to curved crease folding with Kangaroo using an isotropic triangular mesh:
edit - here’s a slightly updated version of the example in the above link
curvecrease_example2.gh (28.3 KB)