Pleat Swing Physics?

[Bugbear]

I have no way of observing this on my own. How does a regular knife pleat move when it swings?

I'm guessing, due to the curve of the kilt, side-to-side hip motion, and the folded edge of the pleat, the pleat swings in a bit of a diagonal motion to it's surface.

Does the... springy-ness of the fabric play a role in the swing?
By springy I mean if the fabric is folded, it has a tendency to resist and unfold itself. For example, I have a swatch of my tartan. If I fold it, it does not stay folded, and I really can't make a crease in it by pinching it. I have an acrylic blanket that I can pinch a fold into, and it stays pinched. There's a slight stiffness to the tartan swatch.

Does that springy stiffness play a role in the swing of a pleat?