You can't gift-wrap a ball
A tow is a flat ribbon of fibres that barely stretch. Lay it on a curved surface and the geometry sends a bill that someone has to pay: the tow steers (its edges disagree on length, so it wrinkles or pulls), it spreads apart or piles up from its neighbours (gaps and overlaps), or it drifts off the angle the designer asked for. Robot precision doesn't make that bill go away.
Predict · at 2:42 in the video
Quick question before we go on. If you cut the tow to half the width, what happens to the tightest turn you can make? The strain is w over two R. Halve w, and you can halve R for the same strain. Half the width, twice as tight. That's exactly why narrow tows exist. An eighth-inch tow can steer where a quarter-inch tow would wrinkle.
So what's the smallest radius you can steer? Honest answer: it depends. On the material, the speed, the heat, and the roller pressure.
Automated Fiber Placement: Status, Challenges, and Evolution, Ramy Harik & Alex Brasington.
- Chapter 5, section 2.2.C
Simulations in this lesson are our own. Where the numbers are invented to show a mechanism, the video says so on screen.
