The magic 54.74 degrees
In netting analysis the fibres carry everything and the resin nothing. A ±α net carries load around a pipe and along it in the ratio tan²α, so a closed pipe, which needs 2:1, is balanced by one pair of helicals at tan²α = 2: 54.74 degrees.
Predict · at 0:58 in the video
Wind a closed pipe at plus and minus 30 degrees and pressurise it. Does it get longer, or shorter?
Shorter, and fatter. At 30 degrees the net is too weak around the pipe, so the pressure opens it like a pair of scissors. The fibres swing towards the hoop direction, the pipe swells, and its ends pull in.
This course is our own. These books go deeper.
- Composite Filament Winding, S. T. Peters (ed.), ASM International, 2011
- Filament Winding: a Unified Approach, S. Koussios, Delft University Press, 2004
Simulations in this lesson are our own. Where a number rests on an assumption, the video marks it with an asterisk and says where it comes from.
