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?

[Wompet]

Let me see if I can word this coherently -
In my experience, the pleats don't swing diagonally to each other as outwards from each other. Then they "flatten" as they swing back into place.
As for springiness, I think it works the other way around. Once the pleats are pressed into place, they want to return to that shape. They may splay out when you walk, but they "spring" back into place at rest.

[Riverkilt]

For sure there's a doctoral thesis in Physics or Textiles lurking in the question....

Ron

[Bugbear]

All right, I have looked at all the different fabric I have around here and given it the pinch test. There is something about that springy-ness of the wool that is interesting to me. My wool kilt seems to have that; though not quite as much as my tartan swatch. It allows the fabric to bend and move, but not crimp or bend into a sharp fold.

My guess is that a fabric without this springy-ness would flop around and rumple instead of swinging. It's like a tendency to flatten out across the fabric surface if suspended.

[Barb T]

I'll ask my physicist daughter/piper/Highland dancer to see what she thinks....

[Bugbear]

Thanks, Barb.

I forget what the term for that springy-ness is... I don't think it's tinsile strength, and I don't know that it would be considered compression.

[ChattanCat]

Hey Ted,
I find that while wearing a tank, the pleats tend to swing side to side. Of course, I only see the end of the swing that I catch when it swings out to the right or the left. Wool has an interesting quality in that with heat and pressure it takes a crease and holds it. While the swing is in progress, the pleats unfold and allow the material to swing sideways. If you don't continue to add momentum, side to side by your walking stride, they return to the original position as pressed.

I'm an engineer but not a textile engineer and this is only my observation.

[Bugbear]

Hey Ted,
I find that while wearing a tank, the pleats tend to swing side to side. Of course, I only see the end of the swing that I catch when it swings out to the right or the left. Wool has an interesting quality in that with heat and pressure it takes a crease and holds it. While the swing is in progress, the pleats unfold and allow the material to swing sideways. If you don't continue to add momentum, side to side by your walking stride, they return to the original position as pressed.

I'm an engineer but not a textile engineer and this is only my observation.

Thanks, ChattanCat.

I'm just a ceramics sculptor, and I really don't deal with this springy-ness much. Although, it is like a material with a lot of flexability and a bit of memory on a small scale that adds up across the whole surface...

BTW, I've had the end of the tartanswatch pinned in a fold for several weeks. I unpinned it and it does have a curve, but no sharp fold. Most other materials would either have a crease or smooth out without any trace of the fold. It's a little bit like some plastics.

[george7]

I would suggest a simple physics experiment. Measure the length of your kilt and the cadence of your typical walk. I'm willing to wager that a good kilt swing is a harmonic of your cadence and the pendular motion of your kilt.

[ChattanCat]

Thanks, ChattanCat.

I'm just a ceramics sculptor, and I really don't deal with this springy-ness much. Although, it is like a material with a lot of flexability and a bit of memory on a small scale that adds up across the whole surface...

BTW, I've had the end of the tartanswatch pinned in a fold for several weeks. I unpinned it and it does have a curve, but no sharp fold. Most other materials would either have a crease or smooth out without any trace of the fold. It's a little bit like some plastics.

Yup, you need to add steam and pressing. If you want to feel the crease, I suggest that you use a pressing cloth (pillow case would work) and spray the cloth with water, then fold the tartan fabric, put the pressing cloth on the fabric and apply an iron. Give it a shot of steam or so, remove the cloth, and place the tartan fabric on a flat surface. After it dries, put the fold apart, the refold it. The crease should be still there. This is what happens when the pleats swing.