The ageing of ropes
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Hi, |
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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. |
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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 |
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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? |
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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? |
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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 surprisingRereading 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 ;) |
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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 ;) |
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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 capacityRapping, 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 ;) |
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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. |
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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. |
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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 ;) |
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The ropes weren´t subject to repeat falls so who knows? |
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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 ;) |
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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 |
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David Coley wrote: Hi, I'm a bit lost. What's that data about? Thankshttps://www.thebmc.co.uk/Download.aspx?id=446 ;) |
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David Coley wrote: Hi, I'm a bit lost. What's that data about? ThanksBearbreeder 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:-) |
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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% ;) |
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If I dieted I could reduce the impact force even more:-) |
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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 ;) |
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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... |
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For more on the effects of #of drops and humidity, see: |