Rock Climbing Forums: Climbing Information: The Lab: Re: [brenta] Common KNs in real world falls: Edit Log

Forums: Climbing Information: The Lab: Re: [brenta] Common KNs in real world falls: Edit Log

brenta

Feb 14, 2010, 9:02 PM

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Registered: Aug 25, 2006
Posts: 50

Re: [brenta] Common KNs in real world falls Report this Post Average: (0 ratings)

brenta wrote:

y is the total amount by which the entire rope lengthens.

I finally got to play a bit more with this problem. The above quote is (rather obviously) incorrect. The total stretch is s2+y: s2 on the belayer's side and y on the climber's side. With octave's help, I got the following graph for the force at the top anchor as a function of the fall factor:

It is not terribly different from those based on Attaway's formulation, but it does show crossings. Reassuringly, for mu=0 my solution coincides with Wexler's. The graph was obtained for k=20 kN.

Of course, the assumption that a rope behaves like an ideal spring is rather crude and masks some interesting effects.

(This post was edited by brenta on Feb 15, 2010, 3:31 AM)

Edit Log:
Post edited by brenta () on Feb 15, 2010, 3:31 AM

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