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The ageing of ropes

Original Post
David Coley · · UK · Joined Oct 2013 · Points: 70

Hi,
does anyone know what the y-axis in this
theuiaa.org/upload_area/fil…
is? i.e. what the experiment was?

Thanks.

wivanoff · · Northeast, USA · Joined Mar 2012 · Points: 674
David Coley wrote:Hi, does anyone know what the y-axis in this theuiaa.org/upload_area/fil… is? i.e. what the experiment was? Thanks.
Isn't the y-axis UIAA drops? That's what I get from the 3rd paragraph.
David Coley · · UK · Joined Oct 2013 · Points: 70
wivanoff wrote: Isn't the y-axis UIAA drops? That's what I get from the 3rd paragraph.
Possibly, but that implies that ropes which might take say 5+ UIAA drops, won't hold a single UIAA drop after about 10,000m of use. Which sounds a bit surprising
eli poss · · Durango, CO · Joined May 2014 · Points: 525

how do they measure use by pitches climbed on? i thought that its elasticity only decreased with every lead fall. if one does 100 30m pitches without a lead fall or TR fall wouldn't the elasticity be close to the original elasticity? or is there something i am missing?

also, given the % sign, my guess would be elasticity or energy absorption capacity

20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
David Coley wrote:Hi, does anyone know what the y-axis in this theuiaa.org/upload_area/fil… is? i.e. what the experiment was? Thanks.
Why not try asking the UIAA?
wivanoff · · Northeast, USA · Joined Mar 2012 · Points: 674
David Coley wrote: Possibly, but that implies that ropes which might take say 5+ UIAA drops, won't hold a single UIAA drop after about 10,000m of use. Which sounds a bit surprising
Rereading the paragraph, I think the y-axis is percentage of original energy absorption. The y-axis has 10 units and is labeled 0, 50%, 100%

That's my final answer ;)
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
David Coley wrote:Hi, does anyone know what the y-axis in this theuiaa.org/upload_area/fil… is? i.e. what the experiment was? Thanks.
Its basically metres i believe

The folks at weightmyrack have done the math to convert the same data to pitches

from WeightMyRAck and UIAA

The implications are fairly self evident

;)
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
eli poss wrote:how do they measure use by pitches climbed on? i thought that its elasticity only decreased with every lead fall. if one does 100 30m pitches without a lead fall or TR fall wouldn't the elasticity be close to the original elasticity? or is there something i am missing? also, given the % sign, my guess would be elasticity or energy absorption capacity
Rapping, lowering, or otherwise using a rope will wear out the elasticity to a certain degree

Whether its enough for it to be very significant with all the other factors in a real life belay is another question

;)
David Coley · · UK · Joined Oct 2013 · Points: 70
bearbreeder wrote: Rapping, lowering, or otherwise using a rope will wear out the elasticity to a certain degree Whether its enough for it to be very significant with all the other factors in a real life belay is another question ;)
Well, by the look of the graph, for the lower line (half ropes) it looks like there is no energy absorbing capacity after a few years, which is either very worrying, or incorrect.

I'll ask the UIAA for the details of the experiment.
Jim Titt · · Germany · Joined Nov 2009 · Points: 490

Well sort of worrying but the ropes still worked o.k and the CMT say the dynamic properties were unchanged (holding force or impact force)in the first fall after the wear, it´s just the number of falls the rope withstands is progressively reduced by use though all the ropes held one test fall after the wear treatment. Anyone taking a FF2 onto a totally clapped out rope will probably retire it anyway as they should even a brand new one.
The word tolerated would probably be better than absorbed on the graph.

bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
Jim Titt wrote:Well sort of worrying but the ropes still worked o.k and the CMT say the dynamic properties were unchanged (holding force or impact force)in the first fall after the wear, it´s just the number of falls the rope withstands is progressively reduced by use though all the ropes held one test fall after the wear treatment. Anyone taking a FF2 onto a totally clapped out rope will probably retire it anyway as they should even a brand new one. The word tolerated would probably be better than absorbed on the graph.
I find it a bit hard to believe that the impact force is not reduced (increased) as a rope gets worn especially after falls

Beal says that it does, but they likely have a bit of a bias as they sell the softest catching ropes out there

;)
Jim Titt · · Germany · Joined Nov 2009 · Points: 490

The ropes weren´t subject to repeat falls so who knows?
Since the impact force rating of the rope is virtually irrelevant to the impact in a real fall and I rarely if ever fall off can´t say as it worries me:-)

bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
Jim Titt wrote:The ropes weren´t subject to repeat falls so who knows? Since the impact force rating of the rope is virtually irrelevant to the impact in a real fall and I rarely if ever fall off can´t say as it worries me:-)
Thats not what out friends at beal say ... But then again they might be a bit biased

BMC Technical Conference 2006

;)
David Coley · · UK · Joined Oct 2013 · Points: 70
bearbreeder wrote: Thats not what out friends at beal say ... But then again they might be a bit biased ;)
Hi, I'm a bit lost. What's that data about? Thanks
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
David Coley wrote: Hi, I'm a bit lost. What's that data about? Thanks
https://www.thebmc.co.uk/Download.aspx?id=446

;)
Jim Titt · · Germany · Joined Nov 2009 · Points: 490
David Coley wrote: Hi, I'm a bit lost. What's that data about? Thanks
Bearbreeder is agreeing with my assertion that the impact rating of the rope is vitually irrelevant to the real impact in a fall and posting data from Beal which shows for example that changing from a 7.2kN rope to a 10kN rope the force on the top piece is increased by 33%.
Add a few runners or a bit more rope drag and change the belay device and the force with the same ropes is doubled. As the chart shows using an appropriate belay device and keeping friction in the system to a minimum is the most important factor in keeping impact forces lower:-)
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
Jim Titt wrote: Bearbreeder is agreeing with my assertion that the impact rating of the rope is vitually irrelevant to the real impact in a fall and posting data from Beal which shows for example that changing from a 7.2kN rope to a 10kN rope the force on the top piece is increased by 33%. Add a few runners or a bit more rope drag and change the belay device and the force with the same ropes is doubled. As the chart shows using an appropriate belay device and keeping friction in the system to a minimum is the most important factor in keeping impact forces lower:-)
There may well be places where one has extended as much as possible and still has significant drag

Basically according to em beal bums the impact force of a rope has as much difference as the belay device

Use both a higher impact rope AND a grigri and the force on the top piece can increase by ~50-100%
;)
Jim Titt · · Germany · Joined Nov 2009 · Points: 490

If I dieted I could reduce the impact force even more:-)

bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
Jim Titt wrote:If I dieted I could reduce the impact force even more:-)
The secret to whipping on marginal gear is to eat rabbit food for the month prior and take da biggest dump before climbing

Secrets u only learn on da intrawebz

;)
dave custer · · Unknown Hometown · Joined Nov 2010 · Points: 2,411
David Coley wrote:Hi, does anyone know what the y-axis in this theuiaa.org/upload_area/fil… is? i.e. what the experiment was? Thanks.
Kantenfestigkeit (richtig: Kantenarbeitsvermoegen)

From Pit Schubert's "Sicherheit und Risiko in Fels und Eis, Band I" page 61

Roughly translates to "reduction of edge performance."

The researchers climbed and rappelled many kilometers and then did drop tests on the ropes over a variety of edge radii. (A very time consuming task, much of which was performed by military recruits with demerits...)

The conclusion is that just climbing and rappelling degrade the ability of the rope to hold a fall over an edge. At about 10000 meters of progress (up or down, it makes no difference), the rope will sustain half as many drops as it did to fresh out of the bag. So, climb and rappel 200 pitches and you've reduced this useful property of your rope by 50%. Thinner ropes have shorter "half-lives." Worth pondering if you like skinny ropes and fractured, alpine granite...
dave custer · · Unknown Hometown · Joined Nov 2010 · Points: 2,411

For more on the effects of #of drops and humidity, see:
"Water absorption and the effects of moisture on the dynamic properties of synthetic mountaineering ropes"
sciencedirect.com/science/a…

Guideline #1: Don't be a jerk.

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