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vivalargo
Dec 2, 2008, 5:30 AM
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In reviewing most of the testing done world wide, the vast majority are slow pull tests, even though no one ever falls like this, and gear is never impacted with super heavy loading (in a real world climbing situation) via slow impact. It's like mashing a car with a hydraulic compactor, instead of driving it at speed into a brick wall. If you want to know how the car actually responds in a wreck, you have to go for the head on. We need to encourage those with drop towers to start doing the work, tedious and involved as it is. JL
(This post was edited by vivalargo on Dec 2, 2008, 5:31 AM)
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suilenroc
Dec 2, 2008, 5:36 AM
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Not sure of the point to this thread... Climbing equipment manufactures are doing drop tests and independent companies/organizations are in fact doing drop tests. Ever noticed that climbing gear is rated in kN?
(This post was edited by suilenroc on Dec 2, 2008, 5:39 AM)
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rgold
Dec 2, 2008, 6:36 AM
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Right on, John. I wish the AAC was more active in supporting such testing. (I think it would be hard for them to be less active...) The distinction between the value of drop testing vs, pull testing comes into sharp relief when one sees the relatively recent tests on dyneema slings, which will break in a factor-2 fall. Nylon slings of the same sort will withstand such a fall, in spite of the fact that their pull-tests give lower tensile strengths. On the other hand, when it comes to metal gear, I think I remember Chris Harmston saying some years ago on rec.climbing that drop and pull testing yielded essentially equivalent results. Moyers has done some interesting drop-testing on what happens when gear pulls. If I can find the reference I'll send it, or maybe someone here already has it. Two things I think came from Moyers drop tests are 1. The rope does recover (spring back) in the interval between blowing the first piece and loading the next one down. Because of this, we can say that extracting a piece can reduce the load on subsequent pieces. 2. Tie-in knots absorb a small but not insignificant amount of the load. But not after the first fall when they have tightened up. The Technique and Materials section of the Italian Alpine Club has carried out and extensive drop-testing program; these guys are light-years ahead of us in their knowledge of belay forces. Some of their work is available through the Canadian Alpine Club web site. I have a translated version of their report on anchor loads somewhere. Again, maybe someone here has a link. It would be very helpful to get their reports translated from Italian. I begged the AAC to do this with little or no results that I'm aware of. It is really close to a scandal that such thorough work has not found its way to an international audience.
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truckyme
Dec 2, 2008, 6:57 AM
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Polymers like spectra and nylon are very sensitive to strain rates. All materials have a plastic flow rate. That means that each material has a rate at which it reacts to stresses. So, the faster that they are loaded the less time the material has to react to the stress. During a slow pull test alot of the energy goes into deformation. where with a fast loading like a drop test the material doesn't have time to deform enough to account for all that energy (think silly putty). IIRC spectra melts at the break due to all that energy going into such small deformation and the material cannot accommodate. Sorry if this is sorta hard to follow. I can clarify if needed.
(This post was edited by truckyme on Dec 2, 2008, 7:17 AM)
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knudenoggin
Dec 2, 2008, 7:20 AM
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rgold wrote: The distinction between the value of drop testing vs, pull testing comes into sharp relief when one sees the relatively recent tests on dyneema slings, which will break in a factor-2 fall. Which tests were these? Recall that Kolin Powick's testing of "girth-hitched" HMPE slings all showed survival of UIAA drops (near FF2)--that's a knotted sling. cf http://www.bdel.com/...ta/qc_kp.php#current [Kolin's 20061109 test of nylon & HMPE slings]
In reply to: On the other hand, when it comes to metal gear, I think I remember Chris Harmston saying some years ago on rec.climbing that drop and pull testing yielded essentially equivalent results. Not just metal gear: I know a fellow who eyed plots of force on some nylon ruptures, and they broke at same force--rapid or slow (and I think that Moyer's results so show). Kolin's results (op cit.) however showed a change in which sling (of mixed-materials cases) broke, if not also force.
In reply to: 2. Tie-in knots absorb a small but not insignificant amount of the load. But not after the first fall when they have tightened up. Hmmm, YMMV on length of fall--the knot has a fixed length of material to yield, which percentage of fall length varies. And, then, not all tie-in knots are created equal. (-;
In reply to: It would be very helpful to get their reports translated from Italian. I begged the AAC to do this with little or no results that I'm aware of. It is really close to a scandal that such thorough work has not found its way to an international audience. And translating to English directly touches more than just USA, as a national-body concern (CA, UK, AU/NZ). *kN*
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majid_sabet
Dec 2, 2008, 7:20 AM
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John Contact Mike Gibb of R4R or Tom Moyer. they have done some drop test on many climbing related gear especially daisy and cords. I have seen some of their drop test videos and does look scary. MS
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USnavy
Dec 2, 2008, 7:46 AM
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suilenroc wrote: Climbing equipment manufactures are doing drop tests and independent companies/organizations are in fact doing drop tests. Ever noticed that climbing gear is rated in kN? That statement only has some very limited truth to it. The only things that UIAA tests dynamically are ropes and helmets (and possibly via ferrata lanyards). Biners, slings, pro, and all the like are tested with a hydraulic puller. Manufacturers generally test their gear in accordance with UIAA standards since they are generally design it to meet UIAA standards.
(This post was edited by USnavy on Dec 2, 2008, 7:47 AM)
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epoch
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Dec 2, 2008, 12:17 PM
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I see some purpose in Largo's post. Why is gear not drop tested? [If this is the line of thought he is going.] Hardware is staticly pulled to failure. We know the manufacturers state the maximum dynamic loading (MDL) on their gear, or at least thier suggested failure load. Why not subject this gear in a drop rig with loads that have been calculated to meet and/or exceed the MDL of the piece. It's a great idea and it would be interesting to see the results of a load-to-failure drop on a piece of hardware.
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adatesman
Dec 2, 2008, 2:46 PM
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binrat
Dec 2, 2008, 6:56 PM
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There is an ACMG guide out by Invermere BC thathas both a slow pull machine as well as a drop tower. He was once the owner of Rigging for Rescue before Mike Gibbs bought the company. He has done lots of drop tests on many things. binrat
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vivalargo
Dec 2, 2008, 7:24 PM
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epoch wrote: I see some purpose in Largo's post. Why is gear not drop tested? [If this is the line of thought he is going.] Hardware is staticly pulled to failure. We know the manufacturers state the maximum dynamic loading (MDL) on their gear, or at least thier suggested failure load. Why not subject this gear in a drop rig with loads that have been calculated to meet and/or exceed the MDL of the piece. It's a great idea and it would be interesting to see the results of a load-to-failure drop on a piece of hardware. The climbing world would never let gear manufacturers rate a rope's fall capacities with data from a slow pull test, and yet most of the other gear and systems (cordelette, et al) are slow pulled tested even though they are subjected to falls. Claims that slow pull and drop testing yield the same results are not terribly convincing. JL
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roy_hinkley_jr
Dec 2, 2008, 8:30 PM
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vivalargo wrote: Claims that slow pull and drop testing yield the same results are not terribly convincing. Actually, there's quite a bit of testing to support the validity of static pulls for most climbing gear. On things like harnesses, it's actually more brutal. All of this was discussed extensively when there was a movement afoot to create ASTM standards. That effort was abandoned when the conclusion was reached that the UIAA standards were adequate to protect companies from lawsuits, their primary purpose. Rgold is correct that the AAC is absolutely pathetic when it comes to testing gear and improving climbing safety (cordelettes are a great example). Instead they focus money on a lame museum, a nice library, and feel-good projects and parties that don't help the majority of climbers.
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vivalargo
Dec 2, 2008, 10:02 PM
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roy_hinkley_jr wrote: vivalargo wrote: Claims that slow pull and drop testing yield the same results are not terribly convincing. "Actually, there's quite a bit of testing to support the validity of static pulls for most climbing gear." I think this is probably true per individual pieces of gear - i.e., how "strong" is this SLCD or that biner. But for systems, such as belay rianchor rigging, et al, for slow pull testing to be valid it would have to have been contrasted with drop tests, with both drop and pull test results worked up into a proper statistical model, contrasted, etc. If this has actually been done, I'd very much like to see it. "On things like harnesses, it's actually more brutal." It's likely more brutal with any single piece of gear, though I certainly don't know for sure, nor have I seen those contrasting tests that would prove it so. "All of this was discussed extensively when there was a movement afoot to create ASTM standards." When, exactly, was this, and who was it who extensively discussed it? Not doubting this information, I just am totally in the dark about the facts of this. "That effort was abandoned when the conclusion was reached that the UIAA standards were adequate to protect companies from lawsuits, their primary purpose." Again, I think this was all in reference to individual pieces of gear, such as nuts and cams and biners and ropes. But the relative strength and performance perameters of said gear is not and has never been the topic of these long winded discussions on fall factors and whether or not we should clip through the anchor and the forces involved when falling directly onto the belay anchor and rigging for equaization and no extensions cha cha cha. Clearly, pull testing would not disclose what we need to know about the above; and I question anyone who claims that it would. How would they know that without contrasting both drop and slow pull testing? "Rgold is correct that the AAC is absolutely pathetic when it comes to testing gear and improving climbing safety (cordelettes are a great example). Instead they focus money on a lame museum, a nice library, and feel-good projects and parties that don't help the majority of climbers. A very crucial point, IMO. I'm going to start putting the screws to the AAC about getting this all straightened out. At the very least we could have the extensive Italian test results translated and interpreted, and perhaps use that as a starting point. We're in dire need of hard facts; and if I learned anything from the first batch of drop tests we did (with Jim at Sterling), the results were sometimes quite diferent than what we had thought all along. JL
(This post was edited by vivalargo on Dec 2, 2008, 10:05 PM)
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gunkiemike
Dec 2, 2008, 10:32 PM
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epoch wrote: I see some purpose in Largo's post. Why is gear not drop tested? [If this is the line of thought he is going.] Hardware is staticly pulled to failure. We know the manufacturers state the maximum dynamic loading (MDL) on their gear, or at least thier suggested failure load. Why not subject this gear in a drop rig with loads that have been calculated to meet and/or exceed the MDL of the piece. It's a great idea and it would be interesting to see the results of a load-to-failure drop on a piece of hardware. I don't think I've ever seen MDL ratings...on anything. Care to point me to some from any of the major gear companies.
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roy_hinkley_jr
Dec 2, 2008, 10:55 PM
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The ASTM climbing committee was in the mid-90s. It consisted of manufacturers, retailers (mostly REI), editors, and interested public with meetings at OR and elsewhere. Shut down after a few years. A related ASTM committee did pass standards for sleeping bag ratings and pack volume. You're correct that UIAA/CEN/ASTM are only about individual gear, they have never tested systems. That's more of a BMC, DAV, CAI on their own thing...but not the good ol' AAC (or ACC). Occasionally a university prof or grad student does something somewhere too but it's very haphazard and often poorly researched. Rescue teams probably do more testing than anyone but a lot of that isn't useful for climbers (Moyers stuff for example). Sharing of info is a very weak point to this day.
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vivalargo
Dec 2, 2008, 11:46 PM
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gunkiemike wrote: epoch wrote: I see some purpose in Largo's post. Why is gear not drop tested? [If this is the line of thought he is going.] Hardware is staticly pulled to failure. We know the manufacturers state the maximum dynamic loading (MDL) on their gear, or at least thier suggested failure load. Why not subject this gear in a drop rig with loads that have been calculated to meet and/or exceed the MDL of the piece. It's a great idea and it would be interesting to see the results of a load-to-failure drop on a piece of hardware. I don't think I've ever seen MDL ratings...on anything. Care to point me to some from any of the major gear companies. Man, I've never even heard of the term, "MDL." Sounds like a very workable idea but I wonder where it has been hiding all these years - and it's not like I haven't combed through most all this stuff. Apparently not well enough. Thanks to Epoch for bringing this up. That much said, to post a valid MDL figure you would have to have drop tested to determine this, unless folks are just assigning a static pull rating to the MDL - which is total BS if so (I can hardly imagine this is the case). Like I have said elsewhere, the reason gear manufacturers (the only folks who have UIAA approved drop towers and all the required gear) only test individual components is that's all they sell. There's no money in testing rigging systems to determine how shock loading occurs, or if this or that sling configuration equalizes or not, etc. Moreover, the closer I look the less it seems that anyone really wants to do the involved drop testing when they can do the much easier slow pull tests and fob off those numbers for most everything. It remains an open question as to who is going to actually test what needs testing per the questions that keep surfacing on this and other sites per anchors, et al. JL
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epoch
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Dec 3, 2008, 12:29 AM
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gunkiemike wrote: epoch wrote: I see some purpose in Largo's post. Why is gear not drop tested? [If this is the line of thought he is going.] Hardware is staticly pulled to failure. We know the manufacturers state the maximum dynamic loading (MDL) on their gear, or at least thier suggested failure load. Why not subject this gear in a drop rig with loads that have been calculated to meet and/or exceed the MDL of the piece. It's a great idea and it would be interesting to see the results of a load-to-failure drop on a piece of hardware. I don't think I've ever seen MDL ratings...on anything. Care to point me to some from any of the major gear companies. I guess that what I meant by the manufacturers stating the MDL is the advertised maximum load of the gear. I assume that during R&D they actually take plenty of individual pieces to complete failure. I agree, though, with the opinion that the loading characteristics between a static pull and a dynamic pull are different.
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vivalargo
Dec 4, 2008, 12:25 AM
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epoch wrote: [I agree, though, with the opinion that the loading characteristics between a static pull and a dynamic pull are different. "Opinion" is right, since I don't know that the loading characteristics between a static pull and a dynamic pull are all that different. I'm not sure anyone really knows, since you'd have to do a stack of tests using both pull methods to determine the differences. Some tests, like for extention/shock-loading would have to be dynamic tests, but for others, who knows, really? JL
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rightarmbad
Dec 4, 2008, 2:04 PM
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Unless some research shows up that slow pull testing, can mask a significant failure mode under dynamic conditions, then there will be no change to testing.
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vivalargo
Dec 4, 2008, 5:53 PM
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rightarmbad wrote: Unless some research shows up that slow pull testing, can mask a significant failure mode under dynamic conditions, then there will be no change to testing. I think this logic is exactly backwards - and if this logic ever gets challenged in a court of law, I believe it will stand no chance because the assumption (that slow pull testing is all that is required to get a full picture of the consequences) is largely unproven. The "research" is basically functional, real world climbing, which involves dynamic loading scenarios. As mentioned earlier, in automotives, they don't allow accident testing to take place in a slow, hydraulic compactor - they require that cars be driven into walls, since that's an actual accident, not a replicatd accident in slow motion (compactor). Where is the testing supporting the belief that dynamic and static loading result in such similar figures that research is required for the industry to change their ways? Who decided this, when, and on the basis of what comparative (slow pull vrs. drop testing) testing? Like I said, whoever has accepted this prima facia is almost certainly in for a rude awakening if ever challenged in court, which is the main reason companies test gear in th first place (to avoid getting sued). I'm all but certain that no one actually knows that slow pull testing does not "mask a significant failure mode under dynamic conditions." Sure, this is the case with individual pieces of gear, such and cams and nuts and biners, which put out similar numbers if slow pulled or drop tested. In face, Colin at Black Diamond explained to me how they test SLCDs and biners and so forth and they dop test the crap out of stuff under far harsher conditions than you could ever encounter in the field (for instance, using static cord with static tie-ins and dropping stuf a country mile - essentially TRYING to break stuff) - but, what about systems (belay systems, rigging systems, and issues like using a redirect off the belay) - these are what remaikn huge question markms for all of us. Consider the drop tests Rock and Ice mag. did a few years ago on using a Spectra daisy chain as a belay anchor tie off. You could have slow pull tested all the components in the system - the anchor, the rigging (cordelette), the biners, the spectra daisy itself, and all would have returned high performance numbers. But when they actually dropped a 150 lb. weight onto a Spectra daisy connected directly to an anchor, shit started blowing up. Again, the testing normally done is with individual pieces of gear, whereas systems and procedures - the topic of discussion on these threads - remain huge unknowns and are IMO not going to give up thir secrets with slow pull testing. Enough said. JL
(This post was edited by vivalargo on Dec 4, 2008, 6:51 PM)
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yokese
Dec 4, 2008, 6:06 PM
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rgold wrote: It would be very helpful to get their reports translated from Italian. I begged the AAC to do this with little or no results that I'm aware of. It is really close to a scandal that such thorough work has not found its way to an international audience. Link to the Italian reports, please?.
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patto
Dec 5, 2008, 1:37 AM
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vivalargo wrote: rightarmbad wrote: Unless some research shows up that slow pull testing, can mask a significant failure mode under dynamic conditions, then there will be no change to testing. I think this logic is exactly backwards. Scientific and engineering theory support this logic. You need to realise that slow pull testing is identical to dynamic pull testing except that the time scale is significantly expanded. For this reason slow pull testing is MORE severe in most cases than 'dynamic' pull. The material is subjected to high forces for a longer period of time. Dynamic testing becomes more severe than static when the rate of onset of the force is larger than the rate at which the material can adjust to the new force. The force wave propagation in metal is EXTRAORDINARILY fast. For this reason metal gear is not a problem. Furthermore due to the presence of dynamic rope means that the onset of the force is (relatively) slow and smooth. The point being dynamic testing is not more severe than static. This is of course NOT true for the rope. Even in the case of a 0m fall. If the rope isn't pulled tight beforehand then the peak force experienced by the rope is double the weight of the purpose. This is because the rope experieces a sharp edge loading profile. Finally, I think you are missing the key difference between ROPE testing and the rest of the gear. ROPE testing isn't about testing the maximum force that it will hold, it is about testing the energy absorbing ability of the rope. It is this energy absorbing profile that determines the forces that will be exerted on the rest of the gear.
vivalargo wrote: The "research" is basically functional, real world climbing, which involves dynamic loading scenarios. As mentioned earlier, in automotives, they don't allow accident testing to take place in a slow, hydraulic compactor - they require that cars be driven into walls, since that's an actual accident, not a replicatd accident in slow motion (compactor). Not really relevent. Science, engineering and common sense indicates that compactor testing has no relevance to automobile crashes. Crashes are about a car resisting/absorbing the forces produce by its own inertia. Alot more complicated than simple tensile forces, the only way to replicate it is crashes.
vivalargo wrote: but, what about systems (belay systems, rigging systems, and issues like using a redirect off the belay) - these are what remaikn huge question markms for all of us. There is a two good reasons why these are being heavily tested. 1. They are too variabe to construct meaningful tests. 2. They are not sold.
vivalargo wrote: Consider the drop tests Rock and Ice mag. did a few years ago on using a Spectra daisy chain as a belay anchor tie off. You could have slow pull tested all the components in the system - the anchor, the rigging (cordelette), the biners, the spectra daisy itself, and all would have returned high performance numbers. But when they actually dropped a 150 lb. weight onto a Spectra daisy connected directly to an anchor, shit started blowing up. Well if you create a belay without an energy absorbing component then don't be surprised if the forces start going off the scale.
vivalargo wrote: Again, the testing normally done is with individual pieces of gear, whereas systems and procedures - the topic of discussion on these threads - remain huge unknowns and are IMO not going to give up thir secrets with slow pull testing. You are right that there might be 'secrets' to be discovered in odd non conforming systems and procedures. However considering most single pieces are large strong enough to handle a fall of any kind, in can be concluded that more complicated systems can also handle such falls. Of course if you mean by non conforming procedures such as having no energy absorber then sure extreme forces can and do happen. Your quest to discover more is very noble. However in my opinion there is little need to subject individual pieces to dynamic testing when slow pull is cheaper more measurable, reliable and repeatable.
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maldaly
Dec 5, 2008, 3:21 AM
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vivalargo, I'm sorry, but I take exception to your comment that manufacturers only test gear so we don't get sued. Bullshit. I climb and fall on the gear we make, Peter Metcalf climbs and falls on his gear, Doug Phillips climbs and falls on his gear and on and on. To say that the only reason we test gear is so we don't get sued is, ill-informed myopic and disrespectful. Shame on you. We test our gear to the best of our ability because we climb on it and, more importantly, our friends, including you, climb on it; and we HATE it when our friends get hurt. We do, however, test to industry norms in part, to cover our asses and, in part, to offer comparative results between brands and models. Without an agreed upon standard there is no possible way to compare one product against another. Whew! Now that I've got that out of my system, I'm happy to discuss if the current standards set by CE and the UIAA are appropriate. Personally, I don't think they are. The best data out there seems to indicate that the tests for metal products--cams, nuts, carabiners--are adequate but incomplete. The tests for webbing based products, however, need some work. For any test to useful, it has to be repeatable, measurable and, most importantly, relevant. It seems like recent tests--anecdotal and otherwise--have shown that tests for webbing don't really evaluate what is going on in a climbing situation. They aren't relevant and need to be revised. The flip side of this is that we're not seeing a lot of gear failures that might be avoided by refinements in testing. Carabiners always have and always will break when the gate is open. Ropes will always get cut over an edge and climbers will still get dropped when their belayer thinks that their Cinch or Grigri is autolocking and climbers will continue to die when they set up their anchors without thinking. Refined testing and more data won't solve this plague. Fewer accidents will happen when climbers stop chatting up the babe next to them and start thinking about what they are doing at the moment. Fewer accidents will happen when climbers worry less about how to rig the latest and most fashionable equalized, cordaletted anchor and start thinking about how to find and place anchors which are bomber and then make them multi-directional. Fewer accidents will happen when sport climbers begin to realize that the time to teach someone how to re-thread an anchor isn't when the climber arrives at the chains for the first time. Okay, enough rant for now. I'm in Florida and a long way from any rock worth climbing so please excuse this quick fix. More later, no doubt. Climb safe, Mal
(This post was edited by maldaly on Dec 5, 2008, 3:40 AM)
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vivalargo
Dec 5, 2008, 3:58 AM
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maldaly wrote: vivalargo, I'm sorry, but I take exception to your comment that manufacturers only test gear so we don't get sued. Bullshit." Hold on, cowboy. I never said that preventing lawsuits was the ONLY reason companies test gear. I talk to Kolin over at BD and know what's up. I probably should have said that the threat of lawsuits - amongst other reasons - necessitates testing. In any event, no disrespect intented. That much said, it's hard to imagine getting more resistance from people about the need to do more actual drop testing ON ANCHORING SYSTEMS, not on individual pieces of gear, for which slow pull tgesting is probably sufficient. Fact is, while I understand that companies do not sell anchoring systems, slow pull tests can contribute only so much here, as can other mechanical models from which things are being extrapolated. The simple truth of the matter is that we don't know the real low down on something as basic as shock loading, and what kind of forces are generatred during the cascade failure of pieces in a belay anchor. But it's late just now - I'll try and get more into this later. But for now, the big problem is that while we know the absolute holding power of many of the components of a anchor chain (nuts, cams, biners, runners, et al), our knowledge of the system is still very much lacking. JL
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altelis
Dec 5, 2008, 5:58 AM
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1) you totally cheestitted that quote 2) john, your gripe hardly seems to be with the gear manufacturers, eh? holding them accountable for not testing systems that may or may not be ubiquitious or made from their products seems like you are just lashing out. perhaps your initial impulse to look towards the AAC was more appropriate. in fact all in all the beginning of this thread was far better than the end. i must preface this next point with: i really have the utmost respect and gratitude for your work and your writing. HOWEVER, the end of this thread has not shown some of your best attributes. it has reduced you to whining and pointing blame at those who do not deserve it. i was excited by the start of this thread and by this point feel like i may just not return. hmph. ~alex
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rightarmbad
Dec 5, 2008, 11:51 AM
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I agree, soft goods, especially the newer thinner lightweight stuff, really does need some more real world testing. Most people simply underestimate how much force is involved, as testament to the look on their faces when belayers go soaring up the cliff face, and amazement at how hot a belay device gets rapping. Trying to tell most people the dangers of falling on slings when above an anchor with much slack out, is met with stares of disbelief. We are spoilt by the forgiving nature of ropes and assume that all other things will be so as well. I wish I knew how much testing manufacturers do in regards to fast pulling of spectra and the like.
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j_ung
Dec 5, 2008, 2:56 PM
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vivalargo wrote: Again, the testing normally done is with individual pieces of gear, whereas systems and procedures - the topic of discussion on these threads - remain huge unknowns and are IMO not going to give up thir secrets with slow pull testing. Enough said. JL Ah, I see now. Yeah, I don't have any beef with that statement. You and Jim pushed this notion forward by leaps and bounds, IMO, when you dropped stuff onto the standard pre-equalized cordalette.
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vivalargo
Dec 5, 2008, 5:37 PM
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altelis wrote: 1) you totally cheestitted that quote 2) john, your gripe hardly seems to be with the gear manufacturers, eh? holding them accountable for not testing systems that may or may not be ubiquitious or made from their products seems like you are just lashing out. perhaps your initial impulse to look towards the AAC was more appropriate. in fact all in all the beginning of this thread was far better than the end. i must preface this next point with: i really have the utmost respect and gratitude for your work and your writing. HOWEVER, the end of this thread has not shown some of your best attributes. it has reduced you to whining and pointing blame at those who do not deserve it. i was excited by the start of this thread and by this point feel like i may just not return. hmph. ~alex I am probably guilty of all the above, but where does this leave us if we just rap off from here? We're left with another conversation that lead to nothing conclusive, backed by a bunch of dismissals by folks who in fact know as little as I do about how the pressing questions per trad belay anchors. Again, we can (for instance) have long discussions about whether or not to clip off the lead rope to the anchor (directional) and yet despite this forum being full of very experienced trad climbers, we can arrive at no solid conclusion. Nobody really knows about the fine points of SRENE. At all. At least not in the context of an anchor system/array and in terms of it sustaining a hig impact fall. What is secure in terms of actual loading? Redundant we have ideas about, but how far should we go with it? Equalization is really anyone's guess. For years I recommended the cordelette and when we tested it I had egg on my face because it didn't equalize at all. There are other rigging systems out there but nobody knows how well they distribute over three or four placements. Many peope/engineers close to the gear trade insist that slow pull and drop testing yield the same results. I disagree, but I'd take slow pull results as a starting point on the issue of equalization. And so far as no extension goes - well, Jim and I did some tests but there needs to be much more done in this regards to understand the true nature of this and cascaded anchor failure. I hound the gear companies because they are the only ones who have the UIAA drop towers and the personel to do the testing. I hound the AAC because in other countries the alpine clubs do testing all the time. We need to know about these anchoring issues, the basic stuff that still remains contentious even amonst old pros. I feel that if these issues do not get settled, American trad routes will start following the European model by bolting all belays. Maybe that's a good thing after all . . . At this point I don't know. JL
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altelis
Dec 5, 2008, 5:52 PM
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I completely agree with your premise. 100%. There is probably nothing more dangerous than listening to advice given on "personal experience" when that experience (no matter how long and varied) does not include any real life "testing" (not in the scientific way but in the "i fell on this system and x happened way). No arguments there. And I commend you for recognizing the problem, not back-peddling when it came to your previous recommendations vs what you and Jim found about the cordallette, etc. Sorry, I actually do think I missed your earlier point about gear companies testing these systems b/c they are the ones with the drop towers. That is a very valid point. Although to my credit, you did very quickly leave that course and started hammering on the gear. And most everybody else picked up on that and we had some serious though subtle 'thread drift'. The problem comes into time, money and resources. Gear companies have the drop towers- how often are they free, what kind of liability do they or do they not face by testing anchor systems and publishing the results, do they have the personnel resources to do the testing, etc. Would looking for a grant from the AAC and renting time on a drop tower work? Would they (either the AAC or the companies) be amenable to that idea? I think that what I was trying to get across was that while I totally agree with your sentiment (at least the academic side of me) I think that pretty quickly, in this thread the means became unproductive- it simply seemed like an unwarranted lashing out at the gear companies (and the AAC, though perhaps that is more warranted...) Certainly interesting stuff here; we are not only asking questions about fundamental facts about our safety systems out on the rock, but also really about who is responsible for ensuring that our communal knowledge is accurate and up-to-date. Perhaps the AAC, most likely not the gear companies, perhaps a new organization? My gut reaction is that if any gear companies should/would get involved it makes most sense for the rope/soft goods manufacturers to, for at least at this stage of the game it seems to be the interaction between their goods and our safety systems that we want to research. But this does not mean that they are the only ones that CAN, or that they have some responsibility to do the testing, etc.
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altelis
Dec 5, 2008, 5:53 PM
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altelis wrote: I completely agree with your premise. 100%. There is probably nothing more dangerous than listening to advice given on "personal experience" when that experience (no matter how long and varied) does not include any real life "testing" (not in the scientific way but in the "i fell on this system and x happened way). No arguments there. And I commend you for recognizing the problem, not back-peddling when it came to your previous recommendations vs what you and Jim found about the cordallette, etc. Sorry, I actually do think I missed your earlier point about gear companies testing these systems b/c they are the ones with the drop towers. That is a very valid point. Although to my credit, you did very quickly leave that course and started hammering on the gear. And most everybody else picked up on that and we had some serious though subtle 'thread drift'. The problem comes into time, money and resources. Gear companies have the drop towers- how often are they free, what kind of liability do they or do they not face by testing anchor systems and publishing the results, do they have the personnel resources to do the testing, etc. Would looking for a grant from the AAC and renting time on a drop tower work? Would they (either the AAC or the companies) be amenable to that idea? I think that what I was trying to get across was that while I totally agree with your sentiment (at least the academic side of me) I think that pretty quickly, in this thread the means became unproductive- it simply seemed like an unwarranted lashing out at the gear companies (and the AAC, though perhaps that is more warranted...) Certainly interesting stuff here; we are not only asking questions about fundamental facts about our safety systems out on the rock, but also really about who is responsible for ensuring that our communal knowledge is accurate and up-to-date. Perhaps the AAC, most likely not the gear companies, perhaps a new organization? My gut reaction is that if any gear companies should/would get involved it makes most sense for the rope/soft goods manufacturers to, for at least at this stage of the game it seems to be the interaction between their goods and our safety systems that we want to research. But this does not mean that they are the only ones that CAN, or that they have some responsibility to do the testing, etc. ^^^^^ i'm not reading that!!!!
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j_ung
Dec 5, 2008, 6:01 PM
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In reply to: I hound the gear companies because they are the only ones who have the UIAA drop towers and the personel to do the testing. I hound the AAC because in other countries the alpine clubs do testing all the time. I'm very much in favor of the AAC moving into this arena. Gear companies, I'm not so sure. I don't think there's an inherent conflict of interest there, but the potential for it is undeniable. Mal and the Trango folk, Jim Ewing, the BD and Petzl guys, many more... they're all fantastic -- trustworthy -- people, IMO. But they won't always be there. As far as the AAC goes, I don't know the reasons why they haven't gone there yet. I suspect it has to do with a lack of funds and a slew of other issues. To be honest, as I sit here at the helm of a site that routinely runs the spectrum from utterly useless to somewhat relevant to the greater climbing community, I'm wondering if there's any small thing we can do to help this become a reality. We have a website with an audience, after all. Then again, perhaps the answer is as simple as helping the Italians with translations. I don't know, but I'd like this conversation to continue. Edited because I also cheesetitted the quotes.
(This post was edited by j_ung on Dec 5, 2008, 6:02 PM)
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cracklover
Dec 5, 2008, 6:31 PM
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vivalargo wrote: That much said, it's hard to imagine getting more resistance from people about the need to do more actual drop testing ON ANCHORING SYSTEMS, not on individual pieces of gear, for which slow pull tgesting is probably sufficient. Fact is, while I understand that companies do not sell anchoring systems, slow pull tests can contribute only so much here, as can other mechanical models from which things are being extrapolated. While I agree with your frustration, it's worth acknowledging that many of the gear companies have already gone above and beyond the call of duty. Two examples spring to mind: 1 - During the Alien fiasco, when CCH was stonewalling and denying any problem, the heads of several companies (including Mal Daly) put their own money on the table, and their personal reputations on the line, by buying Aliens and testing them. It wasn't until they publicly announced the results of those tests that CCH buckled. 2 - Jim Ewing, and Sterling ropes who he works for, put a lot of time, effort, and resources, into helping produce the invaluable research that went into John Largo's book. I ran into Jim shortly after that, and thanked him for volunteering his time. I asked him about some additional research (RGold, you'll know what I'm talking about) that seemed desperately needed to prove the validity of those results he came up with. He agreed with me in principle, but he was entirely justified, IMO, by suggesting that they had already done their duty for the cause. I also talked to Jim about anchoring systems. Frankly, he was sick to death about hearing about them! Remember, these guys are trying to run successful businesses. Maybe if an organization like the AAC was willing to pay Jim and Sterling what their time and expertise is worth, the story would be different. So what about the AAC? This spring, I was sitting at a campfire with Jim Donini, the President of the AAC. He was nice enough to ask me what I thought the AAC should be doing. I must admit, I probably gave him more of an answer than he bargained for! While I expressed my appreciation for the work they do, I also said that it's very disappointing to compare any and all of the European (and Canadian) clubs, with their longstanding safety committees, to what the AAC has in that regard. I also talked about the anchor testing work that J Ewing, J Largo, L Hamilton et al did, and how important it is to keep that going. I will say that Jim Donini respectfully heard me out, but he certainly did not seem interested in pursuing the issues in more detail. But I'm just a nobody weekend warrior. If more pressure could be brought to bear, at least he won't be able to say to you that it's the first time he's heard anyone express interest in it! Cheers, GO
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cracklover
Dec 5, 2008, 6:50 PM
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Pardon the thread drift, but speaking of cutting edge ideas that really deserve to be tested... I know that Jim Sterling was interested at one point in pushing the rope manufacturers to come up with a test for a rope's ability to withstand cutting over a sharp rock edge. A test that gives results that are applicable in the real world. What if a third party were to design such a test? If it was a test that could be repeated by anyone with a drop tower, and climbers really cared about the results (how could they not!) the rope manufacturers would be falling all over themselves to make a rope that did well in the test! In other words, while some manufacturers may be interested, it will take a push from outside to really get the ball rolling. GO
(This post was edited by cracklover on Dec 5, 2008, 6:51 PM)
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vivalargo
Dec 5, 2008, 7:02 PM
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j_ung wrote: In reply to: I hound the gear companies because they are the only ones who have the UIAA drop towers and the personel to do the testing. I hound the AAC because in other countries the alpine clubs do testing all the time. I'm very much in favor of the AAC moving into this arena. Gear companies, I'm not so sure. I don't think there's an inherent conflict of interest there, but the potential for it is undeniable. Mal and the Trango folk, Jim Ewing, the BD and Petzl guys, many more... they're all fantastic -- trustworthy -- people, IMO. But they won't always be there. As far as the AAC goes, I don't know the reasons why they haven't gone there yet. I suspect it has to do with a lack of funds and a slew of other issues. To be honest, as I sit here at the helm of a site that routinely runs the spectrum from utterly useless to somewhat relevant to the greater climbing community, I'm wondering if there's any small thing we can do to help this become a reality. We have a website with an audience, after all. Then again, perhaps the answer is as simple as helping the Italians with translations. I don't know, but I'd like this conversation to continue. Edited because I also cheesetitted the quotes. First things first. I have hardly talked with any gear company that was not willing to look into issues that I raised with them, and in the case of Sterling Ropes and Jim, they did an ENORMOUS amount of work, for absolutely no pay, in working up the most recent tests. I'm sure Mal and others have done a lot of pro bono work simply because they felt it was the right thing to do. My main frustration is that there is no national safety commission or anything like it that can coordinate comprehensive tests and, moreover, can amass the tests that have been made into some coherent whole. As is, we're all working on a whole lot of assumptions and/or mathmatical and engineering models that may or may not be accurate in their relationship to, say, SRENE and belays anchors. The function and performance parameters of individual pieces of gear is VERY comprehensive and well proven. Most all Companies really test the shit out of their products. But the systems we all use remain somewhat mysterious in terms of their functional parameters. Moving on . . . I was just talking yesterday with Colin at Black Diamond and he had some very insightful ideas about what it would take to do the kind of comprehensive testing wed all like to see so we can settle, once and for all, the nagging questions that remain about the most fundamental aspects of the roped safety system. Perhaps the Italians have wrestled all of this down - but I sort of doubt it. Still, getting their treatise translated should be a priority. In the meantime we could at least start formulating questions and narrowing the focus down to the key issues that need to be addressed, such as the effects of extension in a belay anchor during a factor 2 fall, etc. Once some kind of consensus is arrived at per what the real questions are, we might move to devising ways to conduct the tests that will in turn give us the best results. One thing Colin was quite sure of and I totally trust him on this one since hed been testing gear for years is that the working up of what tests need to be made and how to conduct them is totally crucial and needs to be done long before a team heads into the lab. So that, perhaps, is a starting point we can launch into on this site: What are the most pressing and unsettled issues per the roped safety system; what are the tests that can best address these issues; and how should the tests be carried out in order to yield the most definitive results. JL
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cracklover
Dec 5, 2008, 7:05 PM
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j_ung wrote: In reply to: I hound the gear companies because they are the only ones who have the UIAA drop towers and the personel to do the testing. I hound the AAC because in other countries the alpine clubs do testing all the time. I'm very much in favor of the AAC moving into this arena. Gear companies, I'm not so sure. I don't think there's an inherent conflict of interest there, but the potential for it is undeniable. Mal and the Trango folk, Jim Ewing, the BD and Petzl guys, many more... they're all fantastic -- trustworthy -- people, IMO. But they won't always be there. As far as the AAC goes, I don't know the reasons why they haven't gone there yet. I suspect it has to do with a lack of funds and a slew of other issues. I agree completely with the above. However there is the potential, I think, for the AAC to help out already. Their website lists research grants. Most of those in the past seem to have focused on ecological or sociological issues, but the potential might be there if someone has the time, the interest, and the good ideas. Jay, I think rc.com already is serving exactly the purpose it's best at - allowing a forum for the free flow of ideas. GO
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cracklover
Dec 5, 2008, 7:15 PM
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vivalargo wrote: Once some kind of consensus is arrived at per what the real questions are, we might move to devising ways to conduct the tests that will in turn give us the best results. One thing Colin was quite sure of and I totally trust him on this one since hed been testing gear for years is that the working up of what tests need to be made and how to conduct them is totally crucial and needs to be done long before a team heads into the lab. So that, perhaps, is a starting point we can launch into on this site: What are the most pressing and unsettled issues per the roped safety system; what are the tests that can best address these issues; and how should the tests be carried out in order to yield the most definitive results. JL I have some very strong opinions on what would be worthwhile to test, and how to design such tests. But I have neither the equipment nor the time to actually do it. Besides, who's to say that my ideas are the best? In short, someone with the gear and the time needs to take the lead on this. Adatesman, are you volunteering? Want to start another thread soliciting test scenarios? Or would you rather handle it by PM? Again, I'll point out that the AAC does appear to have some grant $$. Whether they'd be willing to shell it out for something like this, I don't know, but I, for one, would be willing to sign on to any grant proposal/petition. I bet lots of other folks would, too! In addition to my ideas, I'd also be willing to volunteer some time and $$, if it were helpful. GO
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adatesman
Dec 5, 2008, 7:18 PM
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reg
Dec 5, 2008, 7:26 PM
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vivalargo wrote: In reviewing most of the testing done world wide, the vast majority are slow pull tests, even though no one ever falls like this, and gear is never impacted with super heavy loading (in a real world climbing situation) via slow impact. It's like mashing a car with a hydraulic compactor, instead of driving it at speed into a brick wall. If you want to know how the car actually responds in a wreck, you have to go for the head on. We need to encourage those with drop towers to start doing the work, tedious and involved as it is. JL that's exactly right - thanks for sayin it. i believe it is possible for a piece of gear to actually see much higher forces then it's break rating at the moment of impact. am i wrong?
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j_ung
Dec 5, 2008, 7:38 PM
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adatesman wrote: j_ung wrote: To be honest, as I sit here at the helm of a site that routinely runs the spectrum from utterly useless to somewhat relevant to the greater climbing community, I'm wondering if there's any small thing we can do to help this become a reality. We have a website with an audience, after all. Then again, perhaps the answer is as simple as helping the Italians with translations. I don't know, but I'd like this conversation to continue. Sounds like you just volunteered, Jay.. Joking aside this is the kind of testing and discussion that you were looking to see here in The Lab when you came up with the idea for it, isn't it? Just throwing the idea out there, but what if we were to take The Lab to the next level and try to tackle some of these issues for the benefit of us all? Its kind of a different model than the non-profit mountaineering organizations, but there may be a way to make it work.... I'm far from convinced that RC.com is the best entity to take the lead in something like this. Plus, it's not my website. Any outlay of funds would at the very least be subject to some hefty approval from on high. And at the other end, it could very well be impossible, especially right now. It also seems like something that could grow far beyond what any of us is prepared to undertake. I assume that's one of the things the AAC considers, too. That's not a "no." That's an "I'm not there yet." Writing, talking, convincing, brainstorming... these things cost nothing but creativity, and that is where I'm (we're) at. Even later, it's more likely that I'd only get as far taking a role in fundraising, soliciting opinions, etc. And yes, this is one of the types of discussions I envisioned when RC.com opened The Lab.
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k.l.k
Dec 5, 2008, 8:09 PM
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maldaly wrote: Fewer accidents will happen when climbers worry less about how to rig the latest and most fashionable equalized, cordaletted anchor and start thinking Yes. I enjoy the armchair engineering we do here in the lab, and I support putting more pressure on the AAC to become engaged in this discussion, but the current cultural climate has drastically over-capitalized engi-dorkery and under-capitalized basic outdoor skills.
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k.l.k
Dec 5, 2008, 8:21 PM
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vivalargo wrote: j_ung wrote: I'm very much in favor of the AAC moving into this arena. Gear companies, I'm not so sure. My main frustration is that there is no national safety commission or anything like it that can coordinate comprehensive tests and, moreover, can amass the tests that have been made into some coherent whole. JL Most academic research is funded by outside granting agencies. Oftentimes, small projects are run off multiple small grants. I doubt that the AAC has anything like the dough to underwrite a serious, ongoing lab. Start-up costs can be staggeringly high, if results are to meet actual peer-review standards. So the prospect of one single, centralized and ongoing lab seems a bit optimistic. But I can imagine enlisting folks willing to undertake discreet tests for thesis or grad projects. In that sort of setting, a small grant could go a long way, especially with donated materials. I don't go to OR, but I would think that those of you who do-- and who either know or are principals at the relevant cos.--might think about creating a small grant fund for systems testing. If we had a small industry granting fund, and maybe a little bit of dough through AAC, there might be enough to get folks to write proposals and apply. No manufacturer is likely to be keen on publishing test results on systems involving gear made by other manufacturers. So far as this site is concerned, can't one of the online wonks compile a list of links to external sites that include already published research?
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nkane
Dec 5, 2008, 8:24 PM
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1. Is there a role here for the hordes of engineering students posting here who a) have access to big university labs and b) need advice for their senior design projects? 2. I'm really excited for someone to post "Hey, Viva Largo - you should go read John Long's book on anchors - he talks about these same issues!." hee hee.
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adatesman
Dec 5, 2008, 8:33 PM
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k.l.k
Dec 5, 2008, 8:48 PM
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adatesman wrote: k.l.k wrote: So far as this site is concerned, can't one of the online wonks compile a list of links to external sites that include already published research? Does this mean I'm a wonk? yes. And an engidork. But you knew that already! Can you link the Kpodas piece? And that master's or Undergraduate Thesis on ropes that came up in the rope-dancing thread? Thanks for trying to organize this. I suspect that the sticky will grow pretty fast. Has anyone with access to a research library actually done a literature search? And yeah, Adatesman, my guess is that old, ivy-covered RCU is not paying you at even the sub-standard RA wage. But there's plenty of folks who post here who do have access. We couldn't link to the articles themselves, but folks could at least have the citations. This isn't my field, or else I'd just do it myself.
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k.l.k
Dec 5, 2008, 8:52 PM
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j_ung wrote: Maybe trying to find some translating is our next step here. Thinking... At the moment, I'm too slammed to get through the Italian I need just for my own projects. But if this drags out long enough (say deep into the summer), let me know and I could try to mobilize some help. (i.e., getting one of my Italian friends drunk enough to check my translations.) Wait-- don't we have Italians here? We're pretty cosmopolitan. Guilt Slablizard into taking a break from porn, atheism, and his real job and contribute to the community.
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j_ung
Dec 5, 2008, 8:56 PM
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Slabby! Now there's an idea.
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roy_hinkley_jr
Dec 5, 2008, 9:43 PM
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vivalargo wrote: I hound the gear companies because they are the only ones who have the UIAA drop towers and the personel to do the testing. I hound the AAC because in other countries the alpine clubs do testing all the time. Not quite true. Rocky Mountain Rescue has a tower (once belonged to Forrest IIRC) and REI used to (they shut down their test lab). It isn't that complicated or expensive to build, though an elevator sure helps since it takes a LOT of up and down trips rigging and derigging each test. I don't have much hope for the AAC getting involved with gear testing. Jim retires next year and Phil is a fundraiser. Everyone on the board is focused on pet projects and they are stuck on a lot of outdated ideas on increasing membership. It's still a dinosaur of an organization even after all Donini has done (he does deserve kudos though). They have one volunteer on the UIAA Safety Committee and he has to pay his own way to go to meetings. We don't have a strong voice in standard development currently and that isn't likely to change any time soon. There just isn't enough money for this type of research and no good potential sources for funding...unless Afghanistan heats up and the military decides climbing is a priority.
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vivalargo
Dec 6, 2008, 5:59 AM
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This from the Beal Rope web site: "The Italian Alpine Club has conducted numerous practical tests, has filmed them, and has measured the loads all along the security chain. On the basis of these results Dr. Bedogni has established a mathematical model allowing the calculation of the loads developed along the security chain in all configurations." This info apparently ended up in a document or treatise, and we definately need a translation of same. JL
(This post was edited by vivalargo on Dec 6, 2008, 6:01 AM)
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vivalargo
Dec 6, 2008, 6:18 AM
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http://www.alpineclubofcanada.ca/services/safety/forms/BelayTechniques.doc http://personal.strath.ac.uk/andrew.mclaren/Turin2002/CD%20congresso/Computer%20mathematical%20models.pdf VERY bad translations of some of the Italian work. JL
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brenta
Dec 6, 2008, 1:57 PM
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If the work by the Italian CCMT is this, http://www.caimateriali.org/...odiAssicurazione.PDF, I think I can help. It will take a while, though. Probably a month. Is it possible to attach a PDF file to a post? The two links above are related to the contents of the booklet, but both predate it. The second, is the paper that Bedogni presented at the 2002 Conference on Nylon and Ropes (http://www.caimateriali.org/index.php?id=31). It's been a while since I looked at this and other papers on simulating belay systems. As I get older, my memory gets less reliable, but I seem to recall that I had reservations on how the slippage of the rope through the carabiner was modeled. Pavier does a better job on that count, but then throws in a magic adjustment in the equations to allow their forward integration to yield meaningful results. I hasten to say that this is not my field of expertise, but I got the impression that there's work left to do.
(This post was edited by brenta on Dec 6, 2008, 2:04 PM)
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rgold
Dec 6, 2008, 4:16 PM
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Brenta, I'd pay to have a good English translation of this! In fact, I think I'll get an estimate from our local technical translation service... Maybe I (we) could get the AAC to host it on their site, since it is much bigger than the .pdf limit here. If it generated some traffic, it might help to pursuade them to attend to climbing safety studies.
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greatgarbanzo
Dec 6, 2008, 4:19 PM
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So... you are saying that drops= KN strength and dead weight= lb? Oh boy.
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greatgarbanzo
Dec 6, 2008, 4:21 PM
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Hey man! if you can find a way to get me that report I will translated for you. I am super interested on the subject.
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jt512
Dec 6, 2008, 4:23 PM
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greatgarbanzo wrote: So... you are saying that drops= KN strength and dead weight= lb? Oh boy. Let's not go there in this thread, ok? Jay
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vivalargo
Dec 6, 2008, 4:36 PM
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Yo, Greatgarbonzo. ŋDonde en Venezuela vive usted? ŋMaricaibo? Eyyyy, calor! La mayor parte de mi vida familiar en Valencia. Sería fantástico si usted podría traducir el documento italiano. Buena suerte. LARGO
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rgold
Dec 6, 2008, 5:57 PM
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greatgarbanzo wrote: Hey man! if you can find a way to get me that report I will translated for you. I am super interested on the subject. Just click the link and download the .pdf.
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brenta
Dec 7, 2008, 4:06 PM
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Jay, thanks! Rgold, I'm about one third through the ordeal. Maybe the one-month estimate was a bit too conservative. I'd be curious to know the estimate by the technical translator. I'd guess $1000 or thereabout. Like everybody else here, I'd like to see a greater involvement of the AAC in these matters. I like the idea of having the Italian Alpine Club study hosted on the AAC site. I presume the authors should be contacted, especially if the English version is to incorporate the figures. Let me know if you want to see drafts of the translation.
(This post was edited by brenta on Dec 7, 2008, 5:27 PM)
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greatgarbanzo
Dec 7, 2008, 5:40 PM
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Hello there! Are you already working on the translation of the Italian article? I am already working on it and thought that it would be kind of dumb to do it twice rigth? Care to share the burden? We can do like half and half! Anyhow, if you are like really busy... well, dont worry, I will get it done pretty soon, is not like I NEED the help... Let me know your thoughs.
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brenta
Dec 7, 2008, 8:37 PM
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Greatgarbanzo, I've gotten to page 18 so far. I'll be glad to collaborate. I've translated the tables and the figure captions, but I've done nothing with the graphs and photographs. I'm typesetting the translation with LaTeX. This allows me to follow the original very closely (it is also typeset with LaTeX) while adding hyperlinks to the document (something missing from the original). I'm striving for a literal translation. As a result, some of it sounds a little stilted, but I'm going to worry about that at a later time.
(This post was edited by brenta on Dec 8, 2008, 1:17 AM)
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greatgarbanzo
Dec 8, 2008, 3:46 AM
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Allrigth! In that case, since you are way ahead of me, just let me know the pages you would like me to translate. Then, I could just send you an email with the translated text so that you can add it to whatever you are doing. Iīll do all the graphs and photographs! dont worry about those!
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brenta
Dec 8, 2008, 4:25 AM
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Very well! Why don't you start from Chapter 2? I already have the bibliography page.
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vivalargo
Dec 9, 2008, 11:37 PM
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One of the things folks could do who have a slow pull rig is to start testing the various rigs used to connect (and equalize) 3 placements into an anchor array - cordelette, equalete, et al. Might reveal some secrets. JL
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tugboat
Jul 20, 2011, 5:39 AM
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wow...lots of opinions and info to read thru and absorb here. I still need to go thru all the post, but i thought i would give my two cents that i collected from when i started my company. I bought a pull tester and started the testing after getting my hands on the UIAA standards and methods for testing manual. I was surprised at the time that all the UIAA certs of the time called for relativley slow hydraulic type pulls and not dynamic tests. So i consulted with several structural engineers at the time. My main question was; "is the force i receive from my slow hydraulic pull representative of a dynamic force number?".... Basically they said "yes"... they replied "a force is a force is a force no matter how you get there". Now in terms of general physics i understand what they are saying; eg 'if the webbing breaks at 5000lbs with a slow steady load, it willl break at the same number when it hits that number dynamically (in general....my qualification added) BUT.... Over many years of busting sewn goods and harnesses i've come to learn that there is other variables going on that come into play when testing things at slower or faster rates. some of these are, but not limited to; heat genrated over time and its dissipation and how it impacts the sewn joint. The settling of fibers in differnet forms over differnet time periods, the legth of time itself that the product is exoposed to the load....and so on. Now some of these issues are significant variables to be investigated for climging and other industrys' purposes and some are not. Spectra's heat properties come to mind. I will restrain with my comments here so as not to show ignorance to those who know much more than myself regarding these issues. On the otherhand,...when i started building stuff, i needed basic numbers to work with and basic standards to build to... UIAA and its standards and methods combined with my engineers' explanations at the time sufficed. But i do beleive that there are "dynamic" issues in certain scenarios that need to be examined and understood.
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jbrown2
Jul 20, 2011, 3:00 PM
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It would be very helpful to get their reports translated from Italian. I begged the AAC to do this with little or no results that I'm aware of. It is really close to a scandal that such thorough work has not found its way to an international audience ------ Google Translate.
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rgold
Jul 20, 2011, 3:15 PM
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Google translate does such a bad job it is hard to tell what the reports say. Both climbing and engineering terminology are not dealt with. Plus GT typically doesn't operate on tables and graphs.
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tugboat
Jul 20, 2011, 4:45 PM
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Actually, i think one of my main questions to the engineers was "does a slow pull force represent what will effect the climber/performer vs a dynamic force?"....and thats where they were emphatic that a force is a force. The variables i see in this case are time exposed to the force.... but the question still remains as to how this effects products.
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rgold
Jul 20, 2011, 5:25 PM
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Of course a force is a force. But your engineers, as far as I know, are wrong about there being no difference in whether the force builds up slowly over a relatively long period of time or builds up over very short intervals. They should know, just for one example, that things like the magnitude of viscous damping depends on velocity, and that, mysterious as frictional effects are, there seems to be a difference between static and sliding friction. They should also know that inertial effects might be significant, as in pulling paper towels off a roll slowly without separating them as opposed to a rapid snap that separates a sheet. I have seen tests on sliding-X load distribution that reached contradictory results depending on whether the tester used slow pull or weight-dropping techniques. Differing friction behavior under these different types of loads might have accounted for this. And we've all seen videos of dyneema slings breaking under dynamic impact loads when nylon slings do not, even though slow-pulling determines dyneema is stronger than nylon. If you want to know what might happen to climbing gear under leader falls, I suspect dynamic loading is the only way to get even first approximations.
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tugboat
Jul 21, 2011, 4:21 AM
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yup...Rgold... i agree with you. thats why i "qualified" what they said in my post. At the time, like i said, i didn't understand why the UIAA testing procedures were almost all non dynamic pulls.... now i know why, and understand more about how dynamic loads can change the test...
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tugboat
Jul 21, 2011, 6:27 AM
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In reply to: If you want to know what might happen to climbing gear under leader falls, I suspect dynamic loading is the only way to get even first approximations. Rgold... i would think that due to several factors "first approximations" are better achieved by using one's testing bed and load cell to get first impressions of one's product. When working on a new product, design, or variation, drop testing hundreds of samples just doesn't make sense. First i would nail down the basic loading strength with my pull tester (this can be hundreds of pulls just on one given pick point out of 25!). Then i take those samples and build a full prototype. Then, back to the testing bed and more neccessary adjustments are made. Finally once the product is proven at this stage, i would go to the drop testing step. Drop testing requires a much higher work load and time alotment than pulltesting. A single drop test, depending on one's facility, can take a full days work. Whereas, pull testing and tweaking samples of a new product can yield tens of tests and variations in a day. This process can be critical if one is working on a completly new design. Its a matter of praticality and manufacturing process. But in the end...i agree,... the product, should be drop tested. Just food for thought... Peace...
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JimTitt
Jul 21, 2011, 7:56 AM
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rgold wrote: Of course a force is a force. But your engineers, as far as I know, are wrong about there being no difference in whether the force builds up slowly over a relatively long period of time or builds up over very short intervals. They should know, just for one example, that things like the magnitude of viscous damping depends on velocity, and that, mysterious as frictional effects are, there seems to be a difference between static and sliding friction. They should also know that inertial effects might be significant, as in pulling paper towels off a roll slowly without separating them as opposed to a rapid snap that separates a sheet. I have seen tests on sliding-X load distribution that reached contradictory results depending on whether the tester used slow pull or weight-dropping techniques. Differing friction behavior under these different types of loads might have accounted for this. And we've all seen videos of dyneema slings breaking under dynamic impact loads when nylon slings do not, even though slow-pulling determines dyneema is stronger than nylon. If you want to know what might happen to climbing gear under leader falls, I suspect dynamic loading is the only way to get even first approximations. You underestimate us! We do know the difference between the application speed of loads and even have a name for it. Rate of strain graphs are commonplace for most materials. And we know a lot about friction as well! The standards and their tests are based on a mixture of theory and practical experience, we can use an item which has for many years giving trouble-free to set a standard which to the normal climber may seem a bit peculiar! The impact speeds encountered in climbing are generally so low in engineering terms that rate of strain has little relevance except in karabiners, textiles are a bit different and here one would expect the experience gained in drop tests to guide the design. To understand what is happening in a fall drop testing is useful but expensive and innacurate. Pull testing on the other hand is cheap and repeatable and for hardware isthe test of choice as the system defines them as a non-dynamic part. Only dynamic elements where the standard limits the maximum force are tested dynamically. There is no repeatable and accurate drop test available as there is no standardised rope to test with, a matter long discussed to no effect for technical reasons. We have ways to work around this but none are good enough to be acceptable to any standards organisation and one still needs to take the results with a healthy sceptiscism! And one then has to ask, "what drop test"? The UIAA test drop distance was set on the pragmatic basis of the drop towers available and the height of a standard industrial unit and is of no particular importance, to achieve "proper" drop results we are going to have to be building 200m high towers to get worst case with commonly used 70m ropes. And despite what another poster wrote, ropes used to be tested under slow pull and my first three ropes were certified using this system. Jim
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tugboat
Jul 21, 2011, 8:21 AM
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Well formulated thoughts and writing Jim,.... thanks for composing such a succint answer.
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tugboat
Jul 21, 2011, 9:11 AM
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Rgold,... given the standards in place for my work and the nature of its requirments I have found (practically) drop test of my harnesses to be less of a valuable test than highly repeptitive, cycle type testing, at lower loads. Indeed loads generated in drop tests (at least in my field of work) are madated to be very low in terms of force. The maxium allowable force for a pic point on my harnesses is 4g loading on the performer. And as a safety factor they ask for twice the 4g restraint force..... they don't mandate it!.... So in adopting (general) UIAA harness stadards for my product,.... i am far exceeding my industry's standards. Continuously, the drop tests reliabley return such low loading numbers compared to the pull tests numbers, that they have become relativley uninteresting to me as regards loading force. Indeed what i have found from my drop tests and years of watching the product practically used, is that small repetitive movements involving mere body weight can be the more dangerous variable. In many ways this info is what drop tests can reveal....not any useful max load numbers. For example, many stunt harness manufacturers use mil spec parachute buckles from the likes of Bourdon Forgecraft etc. The inherent design of these buckles and the general way in which performers use the harness, ends up with the webbing unequally loading the floater bar within the frame. Thus the webbing ends up gathering/sliding to one edge of the buckle frame and either slipping, or exposing a potential 'point loaded' edge to the webbing that could dramatically lower the initial force that would tear the webbing. Other examples of this low impact loading exist....but i hasten to go on....as most will find it incredibly droll stuff.....me included. On the other hand, to apply this logic to climbing, one might consider the new style "quick lock" buckles vs the old double pass buckles. My concern, mostley, is what happens with this buckle under general use and climbing movements,.... rather than their maxium restraint force. Indeed these buckle (i use them on my harnesses) break, without slipping, at incredibly high loads,....but what issues might arise thru general use is more interesting to me. I personally do not like them as a single buckle on a climbing harness for this very reason. I know they are strong, but their other traits concern me for climbing.
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patto
Jul 21, 2011, 10:09 AM
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Wow some great responses by Jim and tugboat here. I started a response yesterday but thought I better get sleep before work. I agree with Jim's and tugboats response regarding drop tests vs pull tests. Furthermore like Jim said the rate of strain in climbing is fairly low. Even for carabiners unless there is metal on metal moving impacts the rate of strain is still relatively low. Sure sliding-x might see differences between pull testing and drop testing but this is a system not a piece of gear. If you want to open up the equalization debate then there is another thread for that.
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JimTitt
Jul 21, 2011, 10:35 AM
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The difficulty with equaliser tests is that frictional hysterisis raises its ugly head. To bend the cord or tape around the karabiner the threads have to be displaced and the faster you pull the more resistance there is internally in the rope as the hysterisis is a time based effect. So a slow pull gives different (lower) values than a drop test . The effect is complicated by the relative amount of load and thus how much internal displacement there is so you need to work on several things at once like load, rope diameter and stiffness and speed. A relatively complex theme! Jim
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nafod
Jul 26, 2011, 5:04 PM
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JimTitt wrote: And one then has to ask, "what drop test"? The UIAA test drop distance was set on the pragmatic basis of the drop towers available and the height of a standard industrial unit and is of no particular importance, to achieve "proper" drop results we are going to have to be building 200m high towers to get worst case with commonly used 70m ropes. As an OBTW, we recently did some tests with energy absorbing devices where we wanted to verify no rate effects were lurking about. After considering a whole slew of different ways to get the rates up, we ended up using an F-350 pickup truck and 200 feet of chain to get to speeds of 45 MPH (66 fps) before loading the device. This is about equivalent to a 70 foot drop. Our goal was quasi-constant velocity over long pulls. Pretty fun test. The chain dynamics make it a poorly controlled experiment, though. We saw no rate dependence for SRDs or tear webbing.
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tugboat
Jul 26, 2011, 7:23 PM
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In reply to: Indeed these buckle (i use them on my harnesses) break, without slipping, at incredibly high loads,.... Actually...i should have said "the webbing breaks at a high load (5000 plus pounds sometimes)".... The frame sees less load than the floater/tension bar component. Thus one might sometimes see manufacturers making the top "floater bar" component thicker or made of a stronger material than the base frame. After tests i have generally seen yielding in the float bar as it wants to be pulled through the frame by the webbing as you reach extreme loads (3000lbs plus).
(This post was edited by tugboat on Jul 26, 2011, 7:24 PM)
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RDouz
Aug 2, 2011, 2:17 PM
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Do you have a reference?
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RDouz
Aug 2, 2011, 2:35 PM
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Hysteresis, as a force is applied the material exhibits one response and as the force is removed the material exhibits another. You are talking about variable impulse and the respective resistances.
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JimTitt
Aug 2, 2011, 5:21 PM
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Thanks for telling me, as it happens I already knew what hysterises is.
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RDouz
Aug 2, 2011, 5:39 PM
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Ok. You are talking about varying the impulse. What are the differences in resistance, quantitatively? How are these values impacting overall performance?
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JimTitt
Aug 2, 2011, 7:26 PM
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Itīs nothing to do with impulses, frictional hysterisis is when the static coefficient remains in force even after the object has started to move, it is properly considered a displacement effect but in real terms itīs easier to regard it as a time-based effect. For some climbing gear it is of relatively minor importance, for other items it is the difference between success and failure. For things like sliding Xīs (which was the subject of my reply) it makes a difference in the test results but no difference in reality since they donīt work as well as hoped anyway. Jim
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RDouz
Aug 2, 2011, 8:33 PM
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Are you saying that the static coefficient remaining constant and not reducing to the typical kinetic coefficient is what constitutes frictional hysteresis? Are you also stating that this phenomenon occurs when forces are applied rapidly as opposed to gradually? For example a peak force "A" achieved in a short time interval <<1s versus the same peak force "A" achieved in a long time interval >>1s.
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JimTitt
Aug 2, 2011, 10:06 PM
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RDouz wrote: Are you saying that the static coefficient remaining constant and not reducing to the typical kinetic coefficient is what constitutes frictional hysteresis? Are you also stating that this phenomenon occurs when forces are applied rapidly as opposed to gradually? For example a peak force "A" achieved in a short time interval <<1s versus the same peak force "A" achieved in a long time interval >>1s. Frictional hysteresis is the time lag (though it has been shown in fact to be a displacement function) in the frictional forces compared to the force causing the friction. It has nothing to do with how fast you apply the forces (in the general sense anyway though Rabinovitz showed the breakaway force decreases with increasing rate of strain but we are talking in milliseconds anyway). In climbing gear the velocity is important since the accelerations are slow.
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RDouz
Aug 5, 2011, 5:32 PM
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JimTitt wrote: The difficulty with equaliser tests is that frictional hysterisis raises its ugly head. To bend the cord or tape around the karabiner the threads have to be displaced and the faster you pull the more resistance there is internally in the rope as the hysterisis is a time based effect. So a slow pull gives different (lower) values than a drop test . The effect is complicated by the relative amount of load and thus how much internal displacement there is so you need to work on several things at once like load, rope diameter and stiffness and speed. A relatively complex theme! Jim Frictional hysteresis is the time lag (though it has been shown in fact to be a displacement function) in the frictional forces compared to the force causing the friction. It has nothing to do with how fast you apply the forces (in the general sense anyway though Rabinovitz showed the breakaway force decreases with increasing rate of strain but we are talking in milliseconds anyway). In climbing gear the velocity is important since the accelerations are slow. Do you have a document that you can reference for me?
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JimTitt
Aug 5, 2011, 6:21 PM
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There are a number of posters on here (and I am one of them) who take a dim view of quoted posts being altered by third persons without it being made clear that these alterations were not in the original post. If you would be so kind as to correct this. A basic overview of the topics and the various models and their justification is in http://www.lag.ensieg.inpg.fr/canudas/publications/friction/dynamic_friction_EJC_98.pdf Essential background reading for those interested in frictional phenomena is probably Engineering Tribology by Stachowiak and Batchelor or one of a number of similar books, more specific to polymers (and thus more indegestable) is Polymer Tribology by Sinha/Briscoe.
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RDouz
Aug 5, 2011, 6:42 PM
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Those are in fact your quotes, you can find them above this reply in the forum. Fitting two quotes on one message isn't misrepresentation nor is it an alteration of the facts. Implying that I have resorted to less than a sincere form of communication is the only infraction that has been made. Thanks for the references. Any comment on the content of my reply?
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JimTitt
Aug 5, 2011, 7:15 PM
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I did not underline any part of my posts. If I wanted to emphasise them I would have done so myself.
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