Ratchet strap coefficient of friction for Capstan calculation

[Wiseel]

Hi All,

Apologies if this is posted in the wrong category... wasn't quite sure where to place it.

I'm trying to calculate the holding capacity of a heavy duty ratchet strap and the effect it would have being wrapped around a cylindrical object (steel bollard or scaffold tube), using the Euler-Eytelwein Capstan equation. To do so, i need to find a suitable friction coefficient for flat, 50mm wide polyester ratchet strap/webbing sling on steel.

There appears to be quite a bit of literature out there for ropes around bollards, obviously due to Maritime interest, but i suppose what i'm after is quite 'niche'. There are lots of strapping articles which point towards BS EN 12195, but i'm afraid i don't have access to it.

Possibly a long-shot, but if anyone could offer any suggestion at all, it would be greatly appreciated.

Cheers

Wise

 

[BridgeSmith]

The friction coefficient should be similar to that of a rope of the same material and construction (woven or braided polyester). If the friction coefficient for the rope is adjusted for local crushing of the fibers, the webbing might have a slightly higher coefficient, since the contact pressure would less, so there would be less flattening of the fibers.

Rod Smith, P.E., The artist formerly known as HotRod10