Theoretical Climbing Rope

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mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Topic Author's Original Post - Jul 6, 2016 - 06:25am PT
Not sure I'm falling for this.

Trevor Dick, shown rock climbing with a rope in Parley's Canyon near S...
Trevor Dick, shown rock climbing with a rope in Parley's Canyon near Salt Lake City, is among four University of Utah mathematicians who published a new study showing it is mathematically possible to design an ideal, dynamic climbing rope.


Credit: phys.org

http://phys.org/news/2016-07-theoretical-climbing-rope-falls.html

What do you say?
Moof

Big Wall climber
Orygun
Jul 6, 2016 - 06:30am PT
Sounds like someone smart talking out of their ass on subjects they are more ignorant about than their PhD will let them admit to themselves.
overwatch

climber
Arizona
Jul 6, 2016 - 06:34am PT
It is kind of what ropes already do is it not? That said new materials that allow it to function better would be a good thing
crankster

Trad climber
No. Tahoe
Jul 6, 2016 - 06:47am PT
Certainly a more interesting topic than what pistol I should buy.
JEleazarian

Trad climber
Fresno CA
Jul 6, 2016 - 10:24am PT
Mathematicians have also proven that it is possible to produce a generator of all prime numbers using powers of a constant. The only problem is that finding the constant is equivalent to finding all prime numbers in the first place, so it doesn't help.

I have no doubt the one may optimize rope characteristics in theory, but proving something possible differs from showing how to do it. WHen it comes to rope, I already know how to do it -- manufacture all climbing ropes to my personal specifications. Who cares if it doesn't satisfy anyone else's needs? I've got what I need. Besides, if the manufacturers do what I ask, they'll be stuck with a boatload of ropes no one but me would want, so I should be able to get it for cheap!

John
JimT

climber
Munich
Jul 6, 2016 - 10:53am PT
A more productive (and dare I say intelligent) idea was being worked on by a Japanese guy maybe ten years ago. You use a static rope and adjust the impact force at the belayer end.
This is naturally exactly how their example of how an aircraft arrestor cable works and clearly not how they think they work.
Incidentally, anyone who thinks smooth braking in a car involves constant braking force is silly, I personally hate coming to a stop with a jerk so feather the brakes off as I slow.
JEleazarian

Trad climber
Fresno CA
Jul 6, 2016 - 11:04am PT
You use a static rope and adjust the impact force at the belayer end.

Jim, the Sierra Club did that in the 1930's with the dynamic belay. Raffi Bedayn was part of the first ascent party on Shiprock specifically for his belaying prowess.

John
donini

Trad climber
Ouray, Colorado
Jul 6, 2016 - 11:07am PT
Just the rope for the theoretical climbers here. In theory it could be produced, in theory they could climb.....in actuality, none of the above.
JimT

climber
Munich
Jul 7, 2016 - 01:44am PT
Not a clue, it was just something that came up when I was doing some reasearch years ago.
The problem with any automatic system is the decision how much rope to let through is taken out of the belayers hands, you´d get the optimum low-force catch until you hit something. Sometimes a hard catch is an advantage!
Ed Hartouni

Trad climber
Livermore, CA
Jul 7, 2016 - 06:34am PT
what funny comments... who "invented" the modern climbing ropes that we use?
How do you think they actually designed that rope?

I'll attempt to get the paper and read it.

But perhaps you could think a little bit before trash talking some designers who had an interesting idea... that's how many technologies start out, many of those technologies we use in modern climbing.

I don't see many pictures of Donini using manilla ropes.
Reilly

Mountain climber
The Other Monrovia- CA
Jul 7, 2016 - 08:01am PT
The carrier arresting system isn't so simple. It is adjusted for the individual aircraft in terms
of weight and landing speed which would require the belay device to be constantly adjusted
with regard to the climber's weight and the fall factor. What could go wrong? Of course, if
it comes from MMM, Murphy Manufacturing of Modesto, then I would feel better.
rgold

Trad climber
Poughkeepsie, NY
Jul 7, 2016 - 10:14am PT
Echoing Ed, some of the ignorance on display here about how science and technology moves forward is sad. But not to worry Luddites, these developments won't be influencing any gear you'll be using.

I can't get the paper directly through my institution; only a handful of US institutions have an arrangement with the publisher. I might try inter-library loan, but that will take a while and I'm not at all sure I have the requisite interest and motivation if I can't get a copy easily. Ed, if you do get a copy, I'd appreciate seeing it if you don't mind.

The main idea behind a "constant force" rope is that, unlike the ideal spring, the tension in the rope doesn't go up as the rope stretches, at least for a broad range of elongation values. Apparently, certain viscoelastic materials can behave this way. The elongation vs. tension graph is mesa-like, a broad level plateau. The same graph for an ideal spring is an ascending straight line.

The fall energy the rope absorbs by stretching turns out to be the area under the elongation vs. tension graph (engineers call this "stress vs strain"). If the rope tension is nearly constant, then we are speaking of an area under a rectangle (the mesa) rather than an area under a right triangle (the ascending line). The rectangle need only be half as high to have the same area as the triangle, which means the peak tension in the rope could be half the value obtained by the ideal spring.

This sounds good for big falls, but maybe not for short falls, which could actually produce higher loads with such a rope than are obtained with something more like a spring, since with the "constant-tension" rope the tension very quickly approaches the constant value. The prospect of a 4 kN impact no matter what doesn't seem to me to be appealing to people whose falls are mostly quite short...
JEleazarian

Trad climber
Fresno CA
Jul 7, 2016 - 02:43pm PT
I hope my comments, above, didn't sound like those of a Luddite, Ed and Rich. My economist's knee-jerk reaction was that "ideal" really means optimal. After all, my ideal rope defies my understanding of physics, since it would have an impact force of zero while simultaneously never stretching far enough to cause me to hit anything, weigh nothing but handle perfectly, have zero rope drag (hence no friction) but be able to be held in any common belaying device, etc. etc.

On a more serious note, thanks for the discussion about energy absorption and fall length. I know the only falls I've ever taken that seriously bent gear were relatively short ones near the start of the pitch (and, obviously, with a very high fall factor), so I found your comments about impact force being highest for shorter falls interesting - and sobering.

Thanks.

John
zBrown

Ice climber
Jul 7, 2016 - 03:50pm PT
The whole world is going down (with) the Tubes


We're white punks on dope
Mommy & Daddy live in Hollywood
Hang myself when I get enough rope
Can't clean up, though I know I should
White punks on dope
White punks on dope


No rope-a-dope comments please


zBrown

Ice climber
Jul 7, 2016 - 03:58pm PT
Here's the abstract. Aparently have to sign up to get the whole article. I don't give out my email to anyone, not to mention cash. Look what happened to H. Clinton.

We consider the rope climber fall problem in two different settings. The simplest formulation of the problem is when the climber falls from a given altitude and is attached to one end of the rope while the other end of the rope is attached to the rock at a given height. The problem is then finding the properties of the rope for which the peak force felt by the climber during the fall is minimal. The second problem of our consideration is again minimizing the same quantity in the presence of a carabiner. We will call such ropes mathematically ideal. Given the height of the carabiner, the initial height and the mass of the climber, the length of the unstretched rope and the distance between the belayer and the carabiner, we find the optimal (in the sense of minimized the peak force to a given elongation) dynamic rope in the framework of nonlinear elasticity. Wires of shape memory materials have some of the desired features of the tension–strain relation of a mathematically ideal dynamic rope, namely, a plateau in the tension over a range of strains. With a suitable hysteresis loop, they also absorb essentially all the energy from the fall, thus making them an ideal rope in this sense too.
zBrown

Ice climber
Jul 7, 2016 - 04:51pm PT
Speaking architecturally or mathematically

http://art-sheep.com/10-amazing-examples-of-architecture-inspired-by-mathematics-2/
hooblie

climber
from out where the anecdotes roam
Mar 7, 2018 - 11:14am PT
bump
Reilly

Mountain climber
The Other Monrovia- CA
Mar 7, 2018 - 11:30am PT
Ironic that just the other day I read about the problems the Navy is having with their new
electro-magnetic arresting system. Of course, in this case it seems clear it wasn’t adequately
tested prior to putting it aboard ship and now that ship, the world’s costliest ever, is basically
useless.

To drift back on topic the history of science is rife with examples of theoretical knowledge
waiting for materials science to catch up.
mcreel

climber
Barcelona
Mar 7, 2018 - 12:34pm PT
Hmm, why does that not sound surprising? Maybe they should buy a few more of them and see if the others work better.
Dingus Milktoast

Trad climber
Minister of Moderation, Fatcrackistan
Mar 7, 2018 - 12:43pm PT
All well and good but what pistol should I buy?

DMT
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