UKC

Hi,
anyone have a readable version of the graph presented in:
http://theuiaa.org/upload_area/files/1/About_Ageing_of_Climbing_Ropes.pdf
and know what the y-axis is (i.e. what the experiment was)?
Thanks.

In reply to David Coley:
One of the less-easier-to-use-graphics...Let us know what you find out. I've wondered the same.


I read a Y scale from 0-100, with 50 marked and ticks every 10. On the Y scale label I read:

Energy ....... (%)

From the text I've always taken a stab in the dark at the Y label to be a bit like this:

Energy absorption capacity......(%)

In reply to David Coley:

The Y axis is the energy absorption capacity of a new rope (100%) decreasing with use as a proportion of the new value for the rope in%.
The X axis is the number of pitches climbed (1 pitch = 30m ascent and 30m abseiled).
The upper curve is a 10+falls rated rope and the lower for 5-9 fall rated rope.

I´m not exactly convinced that energy absorption is the correct term since if the rope had absorbed the energy from abseiling 400 times it would be glowing in the dark at the very least, energy dissapation would possibly be a better description but still probably wrong since a climbing ropes function is to act as an impact attenuator.

In reply to jimtitt:
Agreed : y-axis is the 'energy absorbing capacity' expressed as a percentage of that of the rope when new.
(Energy is absorbed in the form of elastic potential energy when the rope is loaded, and then released again during the recoil and when the rope is unweighted, hence 'absorbing capacity' - it's just a posh way of saying 'old/used ropes stretch less')

The x-axis is "metres of use", and in the text above is explained as "metres of climbing + metres of abseiling". This seems a bit odd, since the amount of load placed on the rope during normal (non-fall) climbing would be minimal compared to that of abseiling and would obviously vary between trad and worked sport / indoor climbing, but it gives a more reasonable comparison with the anmount of rope usage than simply looking at "number of severe falls" or "age since manufacture".

In reply to jimtitt:

Thanks Jim. Any idea how the energy absorption was measured? Was it an impact-like test?

In reply to Ron Rees Davies:

From what I remember the results are really a agglomeration of a number of tests done by CMT and the DAV, the Italians built a simulated wear machine which reproduces abseiling (or lowering) and also did real abseiling tests as well. They wanted a reasonable figure for days of climbing use so included that part as well, while the wear is lower the rope is still dragged around over the rock, through karabiners and naturally through the belay device so there is still going to be appreciable use and in fact the collection of grit which causes much of the damage is far more likely climbing than abseiling. I´ve a vague memory that the DAV did their tests climbing and lowering indoors but that might be wrong.
The impact force was then measured on a Dodero test (UIAA drop test).

The problem with using energy absorbtion as the y axis is it gives a wierd view, the rope must always absorb all the fall energy otherwise the drop weight wouldn´t stop, If it doesn´t then where does the energy go?. The measure we are interested in is how much energy is dissapated by convertion ultimately to heat by internal friction or permanent rope damage and how much stored and given back to the climber as rebound. As the graph is presented we don´t know since we don´t have the 100% values and so it´s a bit confusing.

In reply to jimtitt:

Thanks again Jim. I guess what we want to know is if the y-axis is equivalent to the number of UIAA drop tests the rope might be expected to pass, expressed as a fraction of that given by the manufacturer when the rope was new.

If so, then for 9mm ropes, if this was 10 drops when the rope was new, then if seems like it is less than 1 after a few years. Which sounds worrying.

On the other hand if it is in terms of peak kN on the falling mass in the UIAA drop test, again as a fraction of the force given when the rope was new, this is even more worrying as it would be 10 times the normal force, which I'm guessing would snap a climber in half.

In reply to David Coley:

This is so, it´s the number of test falls the rope survives after the wear which is why absorbed seems a strange word, tolerate describes it better.