Norm_Hall
New member
- Location
- Wauconda, (Chicago),IL,USA
Thought this might be of interest. This is for nylon and polyester fibers only.
Cycles to Failure for Rope
- Thread starter Norm_Hall
- Start date
TreeCo
Carpal tunnel level member
Great info Norm. I bet those figures are the best that can be expected with perfectly clean ropes and ropes exposed to dirt would have even fewer CTF.
Roger_Barnett
Participating member
- Location
- Seattle, in the PNWet
I agree, Dan. But, those are pretty high numbers, and, at least with our work, most activities don't approach that 6-1 factor that the chart shows 1000 cycles for.
TheTreeSpyder
Branched out member
- Location
- Florida>>> USA
Very good, good topic you've brought up/re-minded us aboput before. Is it yours? Do ya mind if i steal it fer my sight?
Norm_Hall
New member
- Location
- Wauconda, (Chicago),IL,USA
Roger, I agree with the 5,000# load. It's a good reference to use for the "working load" though. Just use the chart with your appropriate rope and rating.
- Location
- Springpatch, IL
Hey Norm,
Is this from your personal research, or was this provided by a rope manufacturer?
Mike
Is this from your personal research, or was this provided by a rope manufacturer?
Mike
Norm_Hall
New member
- Location
- Wauconda, (Chicago),IL,USA
Hi Mike, I got this info from a US rope manufacturer. It is for public information, so feel free to pass it along.
Happy Holidays.
Happy Holidays.
- Location
- Canon City ,CO
I can't open that attachment. I'd like to see the info-I know that cycles to failure isn't well understood-A lot of people are worried who need not be.
- Location
- Canon City ,CO
Thanks Glen. I wonder about the testing parameters,-UIAA rope ratings are made my dropping a weight repeatedly for a given distance that creates an impact that is about all a human body can stand. The rope is doubled over a pin/bar that is equivalent in diameter to average 'biner stock. The drop is repeated till failure without moving the location of the bend radius or allowing the shock loaded synthetic fibers to recover. Mountaineers get paranoid about 2 minor falls on their 9 fall rated ropes without understanding that:
A. they didn't load it as much as the test.
B. They probably didn't bend it tight on one 'biner in exactly the same place each fall.
C.They had recovery time between falls-When heavily loaded synthetics(Nylon moreso than polyester) elongate but they recover somewhat and regain some elasticity if rested before heavily loading again.
I have a lot of experience with repeated high loadings of synthetic fibers-With nylon in fishing lines and polyester in bowstrings. The actual cycles to failure are really enormous numbers. A Dacron(polyester)bowstring is typically loaded at from 1 to 10 to as high as 1-4 of strength at rest, and shock loading occurs with each shot-they last for THOUSANDS of shots. I don't challenge the validity of the chart-I just wonder how the numbers are arrived at.
A. they didn't load it as much as the test.
B. They probably didn't bend it tight on one 'biner in exactly the same place each fall.
C.They had recovery time between falls-When heavily loaded synthetics(Nylon moreso than polyester) elongate but they recover somewhat and regain some elasticity if rested before heavily loading again.
I have a lot of experience with repeated high loadings of synthetic fibers-With nylon in fishing lines and polyester in bowstrings. The actual cycles to failure are really enormous numbers. A Dacron(polyester)bowstring is typically loaded at from 1 to 10 to as high as 1-4 of strength at rest, and shock loading occurs with each shot-they last for THOUSANDS of shots. I don't challenge the validity of the chart-I just wonder how the numbers are arrived at.
I've read in some informational PDFs from one (or more) of the major rope maker sites (Yale, Samson, NE) where the real factor is in the ability of the rope to recover from its elongation. If a rope is stressed so much that it will not shrink back to its original length it will have many fewer cycles available. It's also a factor for lighter loads where the rope would shrink back but gets stressed again before it does. In that case the net effect is the same as for the extremely high loading.
Orrrr, something like that...
Looks like some of this is mentioned at http://www.yalecordage.com/html/usage_arb.html but I think the arborist catalog from Samson goes into the detail I was referring to above.
Orrrr, something like that...
Looks like some of this is mentioned at http://www.yalecordage.com/html/usage_arb.html but I think the arborist catalog from Samson goes into the detail I was referring to above.
TheTreeSpyder
Branched out member
- Location
- Florida>>> USA
i think that nylon will generally give this recovery better. i think we watch the tensile more, but elasticity is the more elusive qualtiy, that fades earlier in the rope's useful life.
This finer quality can instantaneously take a degree of dynamic loading off the load(hitches and possibly person), supports, control leg, Porty/Sling and any other devices 'plugged' into the power running along the line.
i think the mountaineers watch this elemeant more and have more elastic lines; we should consider both. And in a line's later life realize it might have the strength for the task, but a newer line might be better for climbing, or other softening impact on specific rigging task/support; other ropework where the last drop of elasticity could make differrance. Conversely might use good older rope as slightly less elastic line for zrig, 5/1 where elasticity is not what ya want.
This finer quality can instantaneously take a degree of dynamic loading off the load(hitches and possibly person), supports, control leg, Porty/Sling and any other devices 'plugged' into the power running along the line.
i think the mountaineers watch this elemeant more and have more elastic lines; we should consider both. And in a line's later life realize it might have the strength for the task, but a newer line might be better for climbing, or other softening impact on specific rigging task/support; other ropework where the last drop of elasticity could make differrance. Conversely might use good older rope as slightly less elastic line for zrig, 5/1 where elasticity is not what ya want.
- Location
- Home of the New Jersey Devils
Hmmm, so, would keeping careful measurements of our lowering lines give us a hint about when top retire them before it's too late?
TreeCo
Carpal tunnel level member
Wouldn't it be ironic if pulleys, friction savers and friction devices hid internal wear as the <font color="red"> cycles to failure </font> count down continues ticking away.
knudeNoggin
New member
[ QUOTE ]
I got this info from a US rope manufacturer. It is for public information
[/ QUOTE ]
Okay, how about a citation?
The circumstances of the testing that produced this data aren't
apparent.
(And showing this for BOTH polyamide & polyester makes me wonder,
as one can find such things showing the difference between them
(with polyester being better for cyclic loading, IIRC)!)
Climbers maybe don't worry enough about some falls: big guys on light,
skinny ropes. PMI did some testing using the UIAA-defined drop but
with heavier loads--rather sobering results (in terms of the generated
peak impact force)!
And while one can (should?) probably track rope use in terms of guaging
retirement, I don't think that it's going to be quite so count-sensitive
as might be suggested by this data (as recovery time in between loading
likely matters, at least at lower loads).
*knudeNoggin*
I got this info from a US rope manufacturer. It is for public information
[/ QUOTE ]
Okay, how about a citation?
The circumstances of the testing that produced this data aren't
apparent.
(And showing this for BOTH polyamide & polyester makes me wonder,
as one can find such things showing the difference between them
(with polyester being better for cyclic loading, IIRC)!)
Climbers maybe don't worry enough about some falls: big guys on light,
skinny ropes. PMI did some testing using the UIAA-defined drop but
with heavier loads--rather sobering results (in terms of the generated
peak impact force)!
And while one can (should?) probably track rope use in terms of guaging
retirement, I don't think that it's going to be quite so count-sensitive
as might be suggested by this data (as recovery time in between loading
likely matters, at least at lower loads).
*knudeNoggin*
