Bend Ratio, Rope Angles, and Reaction Forces

Рет қаралды 22,318

10 жыл бұрын

On this episode of Climbing and Rigging, learn how the bend radius of a rope affects the fibers. Ken Palmer explains rope angle and reaction forces in a way that makes them easy to understand.

Пікірлер: 13

@dragan3290 2 жыл бұрын

And here I was studying physics and fall force etc. Now I stumbled upon your video. So much easier to see a video than from a book. Cheers from Australia just subbed.nice work

@terryhale9006 10 жыл бұрын

Thanks for another quality video. One little quibble. While a beam in pure bending will develop tension on one side and compression on the other, the same will not necessarily be true with a rigging rope. It will develop significantly concentrated tension on the outside and significantly reduced tension on the inside of the bend. In general, it is quite difficult to induce longitudinal compression in a rope, especially when the fibers are independently flexible. If the pulley has a tight radius and the sides provide enough confinement, compression does become possible, Otherwise, fibers on the inside of the bend will adjust laterally and longitudinally to avoid going into compression.

@jrapanut0 10 жыл бұрын

another great video I've tryed to explain this to other climbers but here you guys have out together a great video now there's proof that science combined with arboriculture is good .

@1cleandude 7 жыл бұрын

Very well done Arborpod on a very interesting and important topic!!

@nikoscuatro7251 3 жыл бұрын

great video!!

@65BAJA 4 жыл бұрын

How would the bend radius change if the pulley sheave diameter is still the same? I can see the bend angle changing but not the radius.

@arthurroosen 9 жыл бұрын

Great information on here. One question, if in the end scenario with the two pulleys, both ends of the blue rope were tied off onto the 50lbs block, instead of one of the ends being held by a person, is it correct to assume the force on the blue rope pulley would drop to 50lbs (so half) and therefore the force on the yellow rope pulley also drop to 100lbs?

@TheMadMagician87 3 жыл бұрын

Worlds latest answer. Yes, that's correct.

@dpeterbannister 10 жыл бұрын

Nothing wrong with what's said there. Whilst what Terry Hale says is true, in the video he doesn’t say the rope will be in compression along the primary axis, just that the inside of the bend is in compression. That is true

@terryhale9006 10 жыл бұрын

While the inside of the bend will definitely be compressed laterally (between the pulley and the rest of the rope), it is practically impossible to predict the longitudinal stress of those same fibers. If the pulley was delivering just a slight redirect, rather than 180 degrees, the whole cross section would definitely be in tension, with just a slight difference in the amount between inside and outside. If you hold a rope in your hands and bend it, you feel almost no resistance to the bending until you get down to very small radii, relative to the diameter of the rope. It is only when you make a tight enough bend to feel resistance that you have induced compression in the inside of the bend in the rope. Pulleys are designed to have a big enough radius so that the inside of the rope doesn't go into compression. Some ropes are manufactured to be much stiffer than others and would therefore be more difficult to bend to tight radii, but such ropes are generally not used in tree work. If you bend a rope around a pulley and it doesn't provide much resistance to being bent, there is very little initial compression, and any subsequent tensioning applied to the ends of the rope will only apply tension to the cross-section. There will be no induced LONGITUDINAL compression to the fibers on the inside of the bend. Depending on how the tension of the pull is distributed across the cross-section, the longitudinal tension delivered to the inside of the bend is likely to overcome any compression that was initially there due to the bend.

@dpeterbannister 9 жыл бұрын

Terry Hale Terry, sorry I'm a bit late with my reply! I dont disagree with anything you say there: to do so would just be 'spliting hairs'. But then of course, that could be quite important when talking about ropes!

@terryhale9006 9 жыл бұрын

Thanks for the great series of videos!