The guy who makes the videos often tests the same rope dynamically and statically and gets similar peak load numbers as far as I can tell, and it breaks in the same places. He has a static cell and a 10kHz dynamic one on a drop rig.
What will prob change is the force generated for a given FF between ropes of different age and use. You cannot easily estimate this from a static test unless you also measure strain and use analogues.
Much above 7kN is going to severely damage you. Thus I would think that virtually any undamaged knotted SRT rope (of any age and class B or better) will survive a fall that will kill you. So that isn’t a problem worth worrying about.
If you want a more interesting question, does binding the core to the sheath (as in some new Beal ropes) make the situation worse or better in a shock load situation with ascenders and descenders? I do wonder about ascenders in particular as the sheath sliding absorbs energy without cutting the core. Have they really tested it?
The location of the break is usually the first bend of the active rope within the knot assuming there is no defect somewhere else. See
Pieranski et al for the theory.
10 kHz is a bit slow for dynamic work. The interesting feature is the force v time plot shows a slip / stick phenomena within the knot which is visible in high speed photography (20 kHz frame rate). So when a certain force is exceeded, the rope within the knot slips feeding rope into the section between knots. In doing so it tightens the knot so eventually the knot 'grips' the rope again and stops slippage. This slip / stick phenomena is dependent upon friction and as you may be aware the behaviour of static and kinetic friction is extremely difficult to characterise. Hence my postulate that static testing could be different from dynamic testing.
One can 'measure' strain in dynamic work, we were doing it directly on the now deceased Bradford rig. However, there is also some clever maths one can use to provide a measure.
We have tested used old ropes which broke between 6 and 9 kN. It is also worth noting that the human frame has a reasonable shock absorbing capacity. So the forces seen by a human will be less than that seen using a steel mass. The 6 kN threshold used in standards relates to what an ordinary person should be able to withstand and not be harmed. The survivable force is quite high for fit youngsters, see
Crawford's work. But there have been injuries, notably one guy who severely damaged a vertebrae with a fall of just a few metres.
I'm not sure if the sheath directly contributes much strength. Its role is to compress the core so the strands in the core better share the load; hence the improved capacity of a kernmantle rope compared to a same weight per unit length of a hawser laid rope.
