aluminium port-a-wrap. is that a bad idea?

TheTreeSpyder · Jul 31, 2022

Don't have access to such toys, sorry.
Mainly chasing the maths here, of what happens at what CoF, materials just representatives of those numbers.
They should be good tho, at least tested by others more reputable.
Nylon on Steel CoF from Engineering Toolbox shows the LINEAR FRICTION standards tables can see pretty much anywhere else.
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Nylon on Aluminum was the odder one found in one place, the paper for International Technical Rescue Symposium (1999) The Mechanics of Friction in Rope Rescue by Stephen W. Attaway, Ph.D. that uses the CoF example to bridge from linear to RADIAL FRICTIONS.
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i'd like to think both of these are well tested by those geared and smarter than self.
i think the math logistics is solid, just a point of what material matings are assigned at each CoF?

Bart_ · Aug 9, 2022

Attaway's paper is well done, but purely theoretical. A key missing info in the engineering table is polyester on aluminum/steel. Almost all ropes are polyester sheath, whatever core. And the contribution of the bending of the rope fibers structure is completely ignored.

I once read a 60's or 70's paper with big ship nylon ropes on bollards, but I'm picturing/recalling non-plain-cylindrical shaped bollards, more like those curvy shaped tie off posts. And they were huge nylon ropes. Huge loads too.

I detect a Neil Degrasse Tyson semi driving through the gap....

IIR correctly it might have been Donzelli who did the onset of motion style tests. But he didn't have the luxury of data recording which is a very revealing reality tool. I used two load cells but with the motion method you can get away with one.

Always appreciate your work

TheTreeSpyder · Aug 16, 2022

i have the most faith in the math describing the organic pattern; the logistics of the formulae very sound.
i have the least faith in yes people's assignment of materials mated to particular CoF values . These are meant to be guidelines, and also conditions subject to contaminants, or even purposeful Samthane(magic True Blue coating)etc. finishes.
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i believe what formula reports for .25 CoF, more than what material mix is assigned to .25 CoF. But would hope is more accurate than you reflect!
i do believe frictions by degrees/not distance for radial frictions is correct. Rope is just formable material, subject to same structural geometry laws as any other loaded material.
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TY for your own diligence sir!