International Guild of Knot Tyers Forum
General => New Knot Investigations => Topic started by: xarax on April 25, 2014, 03:22:18 PM
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After losing some more time in practicing the usual tit-for-tat among knot tyers, it is about time to proceed, and tie some knots ! :)
A bowline-like PET loop is a versatile and a useful knot - so a TIB PET loop, is even more versatile, and at least as useful as a non-TIB one. It would be great if we could discover and tie the same ONE knot ( instead of tying two different knots ) either when we want/need to tie a loop in the end of the rope, or when we want/need to tie a loop in the bight, in the middle of the rope - provided, of course, that we do not jeopardise the qualities required from the different knots we are accustomed to use in each of the two cases.
There are many PET TIB loops we already know, and, as I believe, there are many more that we will discover in the future. The eyeknot presented in this thread was known to me for some time now, but I had not noticed that it was TIB - probably because I was not searching for PET and TIB eyeknots when I had first tied it. You have to be lucky to tie a new knot, but "Chance favors the prepared mind", and, at that time, it seems that my mind was not prepared yet for this... :)
It is a very simple two-collar secure bowline, but it is somehow tricky, because the Tail End is not going through the nipping loop, as it happens in most similar eyeknots - and that is what could had been, I think, the main reason it has not been tied already - iff it has not been tied already, of course.
At the present, it is my favourite mistress / loop :) - and I say mistress, because I think of the loops as having a female gender... Perhaps this is due to the two adjacent o s in the word "loop" :) - or to the fact that, in my native tongue { in which I translate, using the Google translator, as it was kindly suggested to me by roo, everything is said against me in this Forum, in order to become able to understand it :) }, the ancient and modern Greek word for "loop" is "θηλεια" [/i]( pronounced : thileia ), which is etymologically directly related to the word "θηλυκο" ( pronounced ; thiliko ), meaning "female". Now, why on earth somebody would had ever thought to relate the "loop" to the "female", is something I leave to the imagination of the reader.
P.S. Perhaps in order to rime with the two o s, or in order to be stronger, the same loop can be tied with two nipping loops ( = a double nipping loop ). I had decided to present only the single-nipping-loop version in this post, so the reader would not be confused with the more complex image of a double Ampersand loop( two collars + two nipping loops). Also, as we have not yet tested the theory, that a double nipping loop is really stronger than a single one ( based upon the idea that, in such a double nipping loop, the distribution of the tensile forces coming from the Standing End, which is loaded with 100% of the load, would be spread more evenly along the rope and inside the knot s nub ), I believe we have to be cautious in suggesting such double nipping loop bowlines. Having said that, I would like to mention that, in the double Ampersand loop, the Standing part is following a very gentle curved path before it winds up and forms the two nipping loops, and that may also be beneficial to the strength of the loop.
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in the double Ampersand loop, the Standing part is following a very gentle curved path before it winds up and forms the two nipping loops, and that may also be beneficial to the strength of the loop.
See the attached pictures of the Double Ampersand bowline, where this "very gentle curved path" is clearly shown.
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I believe this variation to be a secure addition to the bowline family.
That said, I don't believe that a strength increase is what necessarily follows. The dual coil nipping area may give a cushioning effect, but that will allow more frictive crushing to occur.
And it doesn't actually change the contested area of failure's angle.
Consider the offering of Mark Gomer's "Analysis" I have attached.
Also, tie a #1010 standard bowline and this or a "water bowline" and compare the two at this place indicated by the red arrow in the attachment while pulling them very taught. The interference angle is the same, to my eyes.
I would like to see how this would perform in the "magic rope" :) due to its perceived security increase.
SS
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it doesn't actually change the contested area of failure's angle.
What this gentle curve is supposed to do, is to reduce the amount of load which is directly applied on the one end of the nipping coils s "first curve" before the tensile forces reach it. That is, to insert an intermediate additional, new curve, in between the Standing end and the nipping coil : in short, to make the previous sharp "first" curve, second ! :). Even if this added gentle curve is very wide, it may work as a cushion, which will absorb a part, however small, of the total amount of the tensile forces running through the line, and will distribute it on its adjacent / surrounding segments.
Am I sure that this will happen ? That this gentle curve will not be straightened up, during heavy loading ? That, even if it will remains curved, it will not be rotated, as a whole, as a solid arc, and just deliver to its second, lower end exactly the same amount of load which is inserted into it at the first, upper end ? Nooope ! :) Although a knot seems such a simple thing ( knots were invented tenths of thousands of years before the wheel...), as a mechanism, it is very complex - we do not even know the exact form of the path of the rope in a compact overhand knot !
The fact that the rope will probably break or melt at another point, and not at a point along this wide intermediate curve or the sharp "first" curve at the area of the nipping coil, does not mean much, IMHO. I believe that the ropes do not break at the area of maximum loading - but also that it is this area of maximum loading which triggers and propagates the breakage.
It may be proved that all this will be proven to be nothing but hand-weaving arguments, OR that it is a sound theory, indeed - all that is required, is a series of careful , unbiased, repeatable tests ! :) We have the knots, we have the knot tyers, but we do not have the knot tests, so we our basis where we think we stand is not so stable, I am afraid !
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What this gentle curve is supposed to do, is to reduce the amount of load which is directly applied on the one end of the nipping coils s "first curve" before the tensile forces reach it. That is, to insert an intermediate additional, new curve, in between the Standing end and the nipping coil : in short, to make the previous sharp "first" curve, second ! :).
Putting this conjecture to a simple hand strength test, comparing this latest offering and the standard bowline, I don't see any meaningful difference in the approach angle leading to the hard nip first curve. In fact depending on how hard one dresses this knot, the angle just after the standing part enters the collar is more severe. See photo attached.
I believe that the ropes do not break at the area of maximum loading - but also that it is this area of maximum loading which triggers and propagates the breakage.
Care to elaborate on the quote?
I don't believe that we can eliminate the starting or ending point of a rope breaking. It is at that maximum load (at a specific time that may not even be the equal of the rope's stated or unknotted test breaking point) that the chain of failure events lead to rope degradation.
Imo, for synthetic cordage, it is a melting of a few fibers that pass their heat to the neighboring fibers and so on...
In natural type fibers, the load released of one is then passed to the next and so on...
For slippery HMPE the straight line molecular bonds, which are so darn strong, do not like curves and so give them up in severe turns. Add poor heat resistance to this and we can see the need for the slippery coatings. http://en.wikipedia.org/wiki/Ultra_high_molecular_weight_polyethylene (http://en.wikipedia.org/wiki/Ultra_high_molecular_weight_polyethylene)
If there were enough tests done (whenever they are), I believe that the greater portion of the failed bowline style loop knots will have broken in this load nexus area.
SS
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the approach angle leading to the hard nip first curve.
THAT was the subject of my previous post ! :) I did not say anything, anywhere in the previous post about " the angle of approach " ! ( If there was something before the first curve, to make it wider, I would had characterized it as a "deflexion" ). I said something about an intermediate curve, which is NOT supposed to make this angle wider, but ...( Here, you are referred to the previous post ! :))
Also, my comparison, right from my first post, was between the single ( = one nipping loop ) and the double ( = two nipping loops ) Ampersand bowline. The second coil ( of the double Ampersand bowline ), makes the inserted intermediate curve longer, so wider ( than the corresponding curve of the single Ampersand bowline ). ( Read the P.S. of the first post )
I believe that the ropes do not break at the area of maximum loading - but also that it is this area of maximum loading which triggers and propagates the breakage.
The point of the line where the rope breaks is not at the location of the maximum tension - so those two events do not coincide spatially ( or, for that matter, they do not coincide temporally, too, because there may be an hysteresis between the moment the maximum loading is applied, and the moment the rope breaks ). HOWEVER, it is the later which is the cause of the former - but in a strange way we do not know, what happens in the point of maximum tension/elognation triggers the initiation and development of the many complex phenomena that lead to the fracture of the material = the rupture of the line, far away from the source of the whole event. About this issue, I know as much as everybody - that is, next to nothing ! In engineering, when we have such complex catastrophic events, far away from the region of the elastic deformation of the material, the only thing we can do is to raise the margin of security...That is how the "working load" has been lowered to even the 1 /15 of the MBS ! :)
Imo, for synthetic cordage, it is a melting of a few fibers that pass their heat to the neighboring fibers and so on...
So, let us insert some oil in between the fibers, to cool, locally, the heated area, by dissipating the heat generated there within a greater volume ! Try it, using a humble syringe ! :) (1)
1. http://igkt.net/sm/index.php?topic=4246
P.S. The single nipping loop of the common bowline is more free to twist around itself, and so it can be oriented and settle in a position where the deflexion before the first curve is substantial, indeed. The double nipping loop bowlines * the "nipping tube" ) is more rigid regarding this, so both coils are forced to remain at right angle with the Standing Part, and this may lead to a smaller deflexion, and a sharper first curve. You win something, you lose something - the question is, do we really win anything at all, by this duplication of the nipping loop ?
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THAT was the subject of my previous post ! :) I did not say anything, anywhere in the previous post about " the angle of approach " ! ( If there was something before the first curve, to make it wider, I would had characterized it as a "deflexion" ). I said something about an intermediate curve, which is NOT supposed to make this angle wider, but ...( Here, you are referred to the previous post ! :))
Approach angle was my term, yes. And I was talking about the double loop version.
Also, my comparison, right from my first post, was between the single ( = one nipping loop ) and the double ( = two nipping loops ) Ampersand bowline. The second coil ( of the double Ampersand bowline ), makes the inserted intermediate curve longer, so wider ( than the corresponding curve of the single Ampersand bowline ). ( Read the P.S. of the first post )
I did read the entire writing, including the P.S., I just went on from a further point in the discourse. The angle where I see the challenge is not between the collar and the nipping loop, it is at the nipping loop where the standing part and working part contact.
I believe that the ropes do not break at the area of maximum loading - but also that it is this area of maximum loading which triggers and propagates the breakage.
Your quote, not mine
The point of the line where the rope breaks is not at the location of the maximum tension - so those two events do not coincide spatially ( or, for that matter, they do not coincide temporally, too, because there may be an hysteresis between the moment the maximum loading is applied, and the moment the rope breaks ). HOWEVER, it is the later which is the cause of the former - but in a strange way we do not know, what happens in the point of maximum tension/elognation triggers the initiation and development of the many complex phenomena that lead to the fracture of the material = the rupture of the line, far away from the source of the whole event. About this issue, I know as much as everybody - that is, next to nothing ! In engineering, when we have such complex catastrophic events, far away from the region of the elastic deformation of the material, the only thing we can do is to raise the margin of security...That is how the "working load" has been lowered to even the 1 /15 of the MBS ! :)
And why wouldn't the point where the rope breaks not be the maximum tension achieved at that moment? It makes sense that the load would be relatively equal up to that position, in these knots, on their standing parts. Then the knot performs a drastic change in load dynamics.
In this link http://iopscience.iop.org/1367-2630/9/3/065/fulltext/ (http://iopscience.iop.org/1367-2630/9/3/065/fulltext/) it shows what is happening to a monofiliment, which is what a rope is made of (many of them bundled), so extrapolating out from the single filament that breaks, the next and next do so as the load is transferred to them.
My thought is that the inner section of synthetic rope is crushed to a point of high enough temperature to melt, allowing the molecular bonds to release, then the subsequent tensile parts tear.
With natural fibers, it will be the fibers with the greatest tensile strain, the outer ones.
Imo, for synthetic cordage, it is a melting of a few fibers that pass their heat to the neighboring fibers and so on...
So, let us insert some oil in between the fibers, to cool, locally, the heated area, by dissipating the heat generated there within a greater volume ! Try it, using a humble syringe ! :) (1)
1. http://igkt.net/sm/index.php?topic=4246
There are thermal images that show this heat http://www.youtube.com/watch?v=s3fHYGY3YTo (http://www.youtube.com/watch?v=s3fHYGY3YTo) and I don't know that adding a contaminate is useful at this stage of non-testing. ;-)
P.S. The single nipping loop of the common bowline is more free to twist around itself, and so it can be oriented and settle in a position where the deflexion before the first curve is substantial, indeed. The double nipping loop bowlines * the "nipping tube" ) is more rigid regarding this, so both coils are forced to remain at right angle with the Standing Part, and this may lead to a smaller deflexion, and a sharper first curve. You win something, you lose something - the question is, do we really win anything at all, by this duplication of the nipping loop ?
I still believe that both loop knots are going to try and straighten this curve at the nipping area.
In fact if you look at the single nip vs. the double, the standing part has a lower angle. The single approx. 45 degrees and the double near 90. Perhaps that is a contributor to the latter's security, but not necessarily breakage inhibition. Unless the doubled material does indeed provide a non-detrimental cushioning effect. (?) Although it changes the angle at just inside the collar. (Which could then be the point of break.)
SS
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The angle where I see the challenge is not between the collar and the nipping loop, it is at the nipping loop where the standing part and working part contact.
You mean, "where the continuation of the Standing end, and the continuation of the returning eye leg" contact. Yes, this is right on, or very close to, the area of maximum curvature. It is good to try to make this angle wider, but, as I said, when you have a semi-rigid nipping "tube", which is forced to be aligned / remain parallel to the Standing End, you have to make a 90 degrees turn, so you can not do much. The humble common bowline, with its ability to twist the plane of its single nipping loop, can adjust itself better, as you had noticed. As I tried to explain in my previous post, the wider angle of the single vs. double bowlines, in general, should be expected. As you say :
In fact if you look at the single nip vs. the double, the standing part has a lower angle. The single approx. 45 degrees and the double near 90.
However, I repeat that my point was about the intermediate arc, the added longer and wider curved segment, not about the angle of the first curve.
( Also, I had not said anything about the angle "between the collar and the nipping loop" ! I can not even imagine if this angle ( meaning, the angle of the two corresponding planes ) has anything to do with anything ! :) )
Your quote, not mine
I know ! :) I tried to elaborate a little about this quote, as you had asked me to do.
And why wouldn't the point where the rope breaks not be the maximum tension achieved at that moment ?
Good question - if this question is not a rhetoric one. I do not know, and I have not found anybody who knows much more ! :) However, this is what is happening, indeed :
http://iopscience.iop.org/1367-2630/3/1/310/fulltext/
P.S. Thanks for the link. Very interesting ! I should had known this - and perhaps I had, indeed, in the past, but I have forgotten it... This is how one can SEE inside the rope - which is something it would be great if we could apply in the many superficially "similar", yet altogether different knots we have.
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I had read this article in the past, but I have not found it very useful - so it was expected that I will forget it soon ! :) It is about a correlation between the crossing number of stoppers and the point where they break - something that it is interesting, but can not be generalized in the case of a bend or a loop knot, for example ( where we have more than one loaded strings, entangled to each other, some of them been loaded by the one side only, etc. ). I re-post its conclusions here, for an easily accessible summary.
Effects of knot characteristics on tensile breaking of a polymeric monofilament
Hiroki Uehara1, Hiroyuki Kimura, Asami Aoyama, Takeshi Yamanobe and Tadashi Komoto
Department of Chemistry, Gunma University, Kiryu, Gunma 376-8515, Japan
Conclusions
When the torus series of knots were made in a PVDF monofilament, the tensile strength gradually decreased with increasing crossing number. The two reasons for this phenomenon were squeezing and rotation of the filament. At lower crossing numbers, the knot was significantly squeezed due to the lower rotation of the filament. Therefore, breaking occurred at the shoulder position within the knot, where the highest bending was obtained. When the crossing number was increased, the enhanced filament rotation induced torsion within the knot, resulting in breaking at one of the entrances of the knot before squeezing into the entire knot. These effects of filament squeezing and rotation led to a breaking-position shift from inside to outside the knot with increasing crossing number. These results suggest that both squeezing and rotation, which are characteristic for a given knot, dominate the breaking position of the knotted strands.
New Journal of Physics 9 (2007) 65 (http://www.njp.org/)
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Good question - if this question is not a rhetoric one.
Not a bit.
Even if the break is minutely away from the initiation point, that point is still part of it. So, that has to be the maximum load attained, regardless of the rope's breaking strength.
You're welcome, for the link. It is interesting and I believe I've shared it before elsewhere. Memory is a fleeting thing, I know. ;-)
The thermography with the Fig 8 testing video is eye opening too.
However, I repeat that my point was about the intermediate arc, the added longer and wider curved segment, not about the angle of the first curve.
I'm unsure what you mean in the above, apparently.
The longer curved segment I see in the knot is between the collar and the nipping area, ultimately straightens out under higher loads or closer to straight in the double nipping "tube" variation, whereas the single nip allows even a straighter standing part respectively.
Perhaps it does shed some minute amount of force into the nub body. (?) Infrared imaging might just show this.
Maybe there is a smart phone app for this. lol
SS
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I had read this article in the past, but I have not found it very useful - so it was expected that I will forget it soon ! :) It is about a correlation between the crossing number of stoppers and the point where they break - something that it is interesting, but can not be generalized in the case of a bend or a loop knot, for example ( where we have more than one loaded strings, entangled to each other, some of them been loaded by the one side only, etc. ). I re-post its conclusions here, for an easily accessible summary.
Effects of knot characteristics on tensile breaking of a polymeric monofilament
Hiroki Uehara1, Hiroyuki Kimura, Asami Aoyama, Takeshi Yamanobe and Tadashi Komoto
Department of Chemistry, Gunma University, Kiryu, Gunma 376-8515, Japan
Conclusions
When the torus series of knots were made in a PVDF monofilament, the tensile strength gradually decreased with increasing crossing number. The two reasons for this phenomenon were squeezing and rotation of the filament. At lower crossing numbers, the knot was significantly squeezed due to the lower rotation of the filament. Therefore, breaking occurred at the shoulder position within the knot, where the highest bending was obtained. When the crossing number was increased, the enhanced filament rotation induced torsion within the knot, resulting in breaking at one of the entrances of the knot before squeezing into the entire knot. These effects of filament squeezing and rotation led to a breaking-position shift from inside to outside the knot with increasing crossing number. These results suggest that both squeezing and rotation, which are characteristic for a given knot, dominate the breaking position of the knotted strands.
New Journal of Physics 9 (2007) 65 (http://www.njp.org/)
I think this quoted conclusion helps to sell a braid more than a knot or why a splice is so strong.
But, the following quote is very informative. "Up to now in our considerations we neglected the effect of friction on knot breakage. Tightening of real knots is opposed by increasing friction between segments that are pressed together. At some point this friction can be so strong that the string entering a knot will rather break than move further. Therefore real knots may never reach the maximally tight form which could be obtained with ideal frictionless tubes. Studies of the friction in knotted ropes [12] demonstrated that friction is greatly enhanced in the contact regions with high curvature. Therefore when the contribution of friction is not negligible the regions with high curvature at the entrance to the knot will effectively block further tightening of the knot. The level of possible tightening of real knots depends on factors such as the coefficient of inter-segmental friction and the strength of the material from which the knot is made. We decided to follow changes in the curvature of knots during their simulated tightening, although in our simulations friction was not present. Figure 7 shows sequential maps of curvature of a simulated overhand knot during its tightening and the simulated trajectories of overhand knots corresponding to the first and last curvature profiles obtained during progressive tightening. It is visible that both shapes can be considered as very tight and are practically indistinguishable upon visual inspection, however there are differences in the position of the regions with highest curvature (see the colour coding). In a slightly loosened knot the highest curvature is localized shortly after the entrance to the knot and its position corresponds to the experimentally observed breaking points in knotted spaghetti (see figures 5 and 6). In the maximally tight state (that may be only accessible to very slippery materials such as fishing lines) the region of highest curvature is localized deeper in the knot. "
SS
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Even if the break is minutely away from the initiation point, that point is still part of it.
So, that has to be the maximum load attained, regardless of the rope's breaking strength.
I do not see how the first sentence implies the second ! There is a point A, where there is a maximum tension. OK. There is a point B, where the rope starts to break. OK. Why should those two points have to be the same ? If there is flow of temperature involved, vibrations and minute shock waves, propagation of microscopic cracks, etc, there will be a lot of other factors that can separate those two points, causally, spatially and temporally.
I believe that the situation is far too complex to be analysed in separate, partial images, which can then be brought together and paint a coherent larger one. In general, I do not trust the approximations one is forced to accept in his effort to explain the phenomena in such critical situations, because one can not predict how a minute, apparently insignificant side effect can nevertheless trigger a whole cascade of significant ones, and lead to a catastrophic failure. To the degree I can follow the "reasoning" of such analyses, there is too much of hand-weaving arguments and over-simplifications... At the end of the day, nobody has ever predicted where exactly a tensioned overhand knot will break, for KnotGod s sake !
The longer curved segment I see in the knot is between the collar and the nipping area, ultimately straightens out under higher loads or closer to straight in the double nipping "tube" variation
First : HOW MUCH will it be able to straighten out ? It is not alone in empty space, there are other loaded segments near by, forcing it to bent, and remain curved.
Second : Even if, at the end, it will be straightened, would nt it be the case that, in the mean time, during that straightening ( which will not happen instantaneously, of course...), the friction between it and the adjacent segments would have already absorbed a portion, however small, of the impact of the loading force ? Imagine the possibility of an elongated knot, where we can have many such arcs formed in the direct continuation of the Standing End, the one after the other. The whole knot will be able to function like a spring absorber, because the force that will be required to straighten out them will be subtracted from the force that will be able to reach the sharp curve after them - which now we can not even call "first" curve !
In short, one thing is to try to make the angle between the straight continuation of the Standing End and the start of the nipping "tube" as wide as possible. A second thing is to try to make the nipping coils themselves as wide as possible, so the "first curve" will be less sharp. A third thing is to insert some "deflexion" in the recipe, so the continuation of the Standing End is not parallel to the axis of loading, when it reaches the "nipping tube", which is aligned to it, more or less. And a FOURTH thing is to insert an intermediate, however small, wide curve in between the straight Standing End and the "first curve", which can work in tandem with the later, and absorb some tension before it reaches the more critical points.
As you might remember (1), I had even tried to make the continuation of the Standing End follow a helical path, before it reaches the nipping loop - and, doing this, I had discovered that such a curved segment is able to do the whole job by itself, alone, without the help of any nipping loop at all ! This made me to appreciate what a curved segment formed on the Standing Part can do - and when I see one, however small, I welcome it ! :)
1. http://igkt.net/sm/index.php?topic=3020.msg21688#msg21688
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The passage quoted in Reply#10 is very interesting, indeed. However, it speaks about the relation of the point where the line breaks, to the point of maximal curvature - which in not directly related to the point of maximal load ! What happens when the maximal curvature is deep inside the knot s nub, in its core, well after the "first curve" ? The authors claim that, in that case, the line will break somewhere inside the nub - but this, by definition, would NOT be the point where the load is maximum. A lot of tensile forces would had been absorbed till they would be able to reach this point, by their contact to the segments at the outer shells of the nub.
We have to accept the fact that dew people bother about knots, and even fewer about knot strength ! So, we should expect that the scientific studies on this obscure issue will be few, and of a questionable quality. Till we have some real brek through, we are forced to tie knots, and test them - or hope/pray that thee will appear somebody else out there, who will test them - that is, rely on OPT ( other people s tests). :)
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The authors claim that, in that case, the line will break somewhere inside the nub - but this, by definition, would NOT be the point where the load is maximum. A lot of tensile forces would had been absorbed till they would be able to reach this point, by their contact to the segments at the outer shells of the nub.
I don't necessarily agree with your assertion , that by definition...
The force will still be there at the first curve attempting to further constrict the first curve and beyond. Since the nub is maximally tight something has to give. So, the weakest link in the rope is the first curve, even within the knot. It can't be any further than that, because by definition, it is maximally tight. I think the "outer shell" may restrict the escape of forces outward, but not linearly.
And with real rope, I don't think we will come very close to the theoretical/simulated maximally tight one they have offered.
SS
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Even if the break is minutely away from the initiation point, that point is still part of it.
So, that has to be the maximum load attained, regardless of the rope's breaking strength.
I do not see how the first sentence implies the second ! There is a point A, where there is a maximum tension. OK. There is a point B, where the rope starts to break. OK. Why should those two points have to be the same ? If there is flow of temperature involved, vibrations and minute shock waves, propagation of microscopic cracks, etc, there will be a lot of other factors that can separate those two points, causally, spatially and temporally.
Yes, we can go about frequencies and gamma ray generation ;), but a weak place starts where the crack etc. starts. Even down at nano and smaller. We'll have to take this elsewhere if we care to delve further.
But, my point was that once a crack/tear/whatever starts, I believe that is the end of the maximum force attained. The major break destruction can or most likely be away from that point as the tensile force diminishes in the direction of force flow. As broken rope shows the non clean rupture results.
I believe that the situation is far too complex to be analysed in separate, partial images, which can then be brought together and paint a coherent larger one. In general, I do not trust the approximations one is forced to accept in his effort to explain the phenomena in such critical situations, because one can not predict how a minute, apparently insignificant side effect can nevertheless trigger a whole cascade of significant ones, and lead to a catastrophic failure. To the degree I can follow the "reasoning" of such analyses, there is too much of hand-weaving arguments and over-simplifications... At the end of the day, nobody has ever predicted where exactly a tensioned overhand knot will break, for KnotGod s sake !
It is complex, I agree, but I don't think it is beyond comprehension. I think that I could predict where a piece of glass will break if I score a insignificant line across it. A couple of rope's fibers weakened by some outside force, in an extreme load scenario, surely could be predictable. Say touch a knife to the side of it.
Even though my hand waving and over simplifications are not scientific, by any means, they are correct. Hmm, I don't think I've been parroting anybody. :)
I myself am not qualified to go to the molecular side of things, I have no formal training there. But, for this simple mind, the analogies make sense.
For the purpose of this thread and many others, some simple pull and drop tests should suffice.
I think that the double nipping loop version of the Ampersand bowline will test out to be very secure and I believe that it will do well in a drop test too.
SS
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The "by definition" was referring to the "inside" - a point "inside" the knot s nub, is a point which can be reached only ( if the flow of the force has already gone ) through the "outside" - so, only if some load, however small, has already been uploaded, at the segments occupying this "outside", "at the segments at the outer shells of the nub", as I wrote. In short, I do not believe that the point of the maximum load can be located deep inside the nub, at its core - most probably, it will be located at its outer shell, right after the entry of the straight continuation of the Stranding End into the nub, where the tensile forces are still at their peak, at the 100%. However, the line seldom breaks there - why ?
I think that the breaking point is determined ( if we can use this word, for such a mess...) by a combination of many factors - where the maximum load is, where the minimum curvature is, where the maximum temperature, generated by friction, flows, which part is compressed, which is elongated, and who knows by what else, but it does not coincide with any of them.
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once a crack/tear/whatever starts, I believe that is the end of the maximum force attained.
Nooo ! You confuse the cause and the effect ! The cause is the existence of the nano-crack at this particular point, and nowhere else, the impurity in the composition of the material which makes its "local" MBS lower, etc. The force which will break the rope at this point, can well be less than the maximum load. The chain breaks at its weakest link - BECAUSE this link is weak ! The maximum force may well be attained elsewhere, where it may be confronted by a stronger link...
For the purpose of this thread and many others, some simple pull and drop tests should suffice.
I am not sure about what "the purpose of a thread" really is ! :) Perhaps the purpose of a thread is the purpose of the thread : just to be long, continuous, and connect many things together - but never end ! :)
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The most important segment of the ampersand-shaped collar structure, is the last segment of the Tail End, which is squeezed in between, and it is nipped by, four segments of the nipping structure, from four sides :
1 : From the "lower" side, it is nipped by the arced continuation of the Standing End into the nipping loop ( near the nipping loop s crossing point) which is also part of the first curve of the Standing Part.
2: From the "upper" side, it is nipped by the arced continuation of eye leg of the Standing Part into the nipping loop ( near the nipping loop s crossing point ) which is also part of the first curve of the eye leg.
3: From the "rear-right" side, it is nipped by the first leg of the collar - which, in its turn, is pushed towards it by the first curve of the eye leg of the Standing Part.
4: From the "front-left" side, it is nipped by the second leg of the collar - which, in its turn, is pushed towards it by the first curve of the Standing part.
Moreover, at all those four points, the last segment of the Tail End meets the segments of the nipping structure at an angle very near the right angle ( which right angle, is the right angle, indeed, two segments which are squeezed onto each other should better meet, in order to be able to bite hard and deep into the flesh of the material, and block the mutual sliding / slippage more efficiently ).
Until this last segment, where the blockage of the sliding/slipping takes place, the Tail follows this easy ampersand-shaped path, so I guess that, in a tight nub, the whole collar structure will be tensioned - so, when the knot will have closed around itself, there will be no parts that will run the danger to remain rather slack, and do not participate in the working of the knot as much as the rest.
All this sounds nothing else - and it may well be nothing else - but boring blah-blah, of course ! All the interested reader is kindly requested to do, is to take the cord which happens to be closer to him, form a nipping loop, attach within it an ampersand-shaped double collar, draw the eyeknot taught, and see, by his own eyes of his own mind, what happens ! :)
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0.
So, you do want to tie the Ampersand bowline in-the-bight... Evidently, you have to start from a bight ! :) Place its tip at the right side, so you will tie it using mostly your right hand. ( Left-handed people should do the exact opposite. )
1.
With your right hand, twist this bight three times, 180 degrees each time, clockwise, like you turn a screw : righty-tighty.
Why "three" times ? Because there are "three" bights in a bowline : the eye, the collar and the nipping loop.
Have you swallowed this "because" ? I hope not ! :) Just remember to twist the initial bight three times, 180 degrees each time. I guess that there should be a number of other mnemonic ways to remember the number "three" :) - I have just utilised one which, although it means absolutely no-thing about why, in this particular tying method, this particular bight of this particular TIB bowline should be twisted three times, it does mean something about the three bights of the bowline, in general... :)
2.
At the "upper" line leading to the twisted three times bight, and with your left, now, hand, form a right-handed nipping loop, and hold it by squeezing its crossing point in between your thumb and your index finger. Notice that, when they hold the nipping loop by squeezing its two legs at its crossing point, the thumb and the index finger themselves form an eye, too, symmetric to the eye of the nipping loop :) . Notice also that, if you have formed a right-handed nipping loop, indeed, and not a left-handed one, both its legs would be perpendicular to the corresponding finger they are in contact - not parallel to it. If you would find out that your fingers are parallel to the legs of the nipping loop they are in contact, you would have formed the nipping loop wrongly : straighten it out, and then form it again, with the correct handedness. ( I like this haptic way of self-assuring that a nipping loop is right-handed, by just touching it - so one may use this way even if he ties the bowline in the dark ).
3a.
( This 3a is step used only to paint an easy to remember mental image, and to describe its various parts. It can be bypassed after some time and practice ).
Push the tip of the twisted bight somewhat to the left, towards its twisted legs, in order to form two smaller sub-bights : the "upper" one, which will become the collar of the bowline, and the "lower" one, which will become the eye of the bowline. So, now we have the three bights of the bowline we were talking about when we were trying to memorize the number "three" ( we have to twist the initial bight "three" times, 180 degrees each time, clockwise - remember ? :) ). In fact, we don t even need to separate the initial twisted bight into two smaller ones : we can just grab the "upper" half part of the initial twisted bowline, move it to the left, and reeve it through the nipping loop, following a "first under / then over" path, leaving the remaining half part outside the nipping loop, at the right. After we will complete this stage, we will need two, only, moves, to tie the Ampersand bowline.
3b.
Reeve the "upper" bight ( the one which is going to become the collar of the bowline ) through the nipping loop, from "right" and "below", to "left" and "above" of the nipping loop. So, now the "upper" bight has been moved, and it is located in the left side, and the "lower" and "right" bight has remained where it was, in the right side. We can now see the nipping loop, and the collar which goes through it - but, how on earth will this collar manage to encircle the Stranding and the Tail End, which do not penetrate it at this stage?
4.
Piece of cake :) ! By pure knotting magic :) : Just reeve the whole knotted part of the line you have already formed through the "upper"/left" bight of the collar, so that the two free lines, the Standing and the Tail Ends, will become encircled by it ! In fact, after some time, you will find out that it is much easier to do the same thing the other way - that is, it is much easier to move only the bight of the collar, first "over", then to the right, and then around the rest of the knot, and engulf / encircle it. So, doing this, you will have to move only the "mouth", the bight of the collar, and not what will be "swallowed" by it, the rest of the knot. When this "mouth" will be all around the bights of the eye and of the nipping loop, just push it to the left, to the side of its final destination.
5.
After you push the "upper"/left" bight ( which will become the collar of the bowline ) to the left, now pull the "lower"/"right" bight, ( which will become the eye of the bowline) to the right, all the way - until the bight of the collar, which is communicating with the bight of the eye, shrinks as much as possible. Congratulations ! You have just finished the tying of the Ampersand bowline, in-the-bight. And you may even have memorized the number "three" ! :)
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I do not know if I should had expected this - but I did not ! :) Without any access to the tip of the eye ( that is, without tucking or un-tucking the bight of the eye ), the Ampersand TIB bowline can be transformed into the Scot s TIB bowline, and vice versa. A nice knotting puzzle for the interested reader ! :)
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The "by definition" was referring to the "inside" - a point "inside" the knot s nub, is a point which can be reached only ( if the flow of the force has already gone ) through the "outside" - so, only if some load, however small, has already been uploaded, at the segments occupying this "outside", "at the segments at the outer shells of the nub", as I wrote. In short, I do not believe that the point of the maximum load can be located deep inside the nub, at its core - most probably, it will be located at its outer shell, right after the entry of the straight continuation of the Stranding End into the nub, where the tensile forces are still at their peak, at the 100%.
However, the line seldom breaks there - why ?
How do you know where line typically breaks?
As you have surely read (ABOK/Ashely, e.g.),
that is precisely where the break is said to occur
--or even "slightly outside of the knot"!! (?!)
My take on the "outside" observation is of a double
mitigation, so to speak : (1) that the actual breakage
has been started within the knot, and it only seems
that "the break" occurred outside (I think that this is
partly what you argue, elsewhere); and (2) that the
broken area has been grievously weakened when
inside, and only later broke though it had moved
farther from that point.
My observations suggest that compression at a bend
plays a big role, with the inner / compressed fibres
being what break (first). In one case of slippery, HMPE,
the break seemed to come well inside, which I credit
to the material being able to deliver high tension
--w/o mitigation /"off-loading" via friction-- much
father along the SPart's path (this seemed to be
past the SPart's U-turn, of all things!).
And I think that (single strand!) spaghetti is not a good
model for normal cordage! Monofilament might suffer
some of the same problems for representing rope.
--dl*
====
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Perhaps I had not expressed what I was thinking clearly enough. I wrote that :
... the point of the maximum load ... most probably ... will be located ... right after the entry of the straight continuation of the Stranding End into the nub... However, the line seldom breaks there
, meaning that, as I had read and seen in many pictures of broken knotted lines ( for example, in the pictures of ruptured loops by Alan Lee, presented in this Forum ), the line typically breaks before "the entry of the continuation of the Standing End into the nub", not "right after" it, at the point of maximal curvature, as we would had expected.
the broken area has been grievously weakened when inside, and only later broke though it had moved farther from that point.
I think that a severe weakening of the line can only happen during the last stages of the tightening, when any slack that could had been consumed by the pulling of the Standing End(s), would had been consumed already, and the knot s nub would have been shrank to near its most compact form. So, during those last stages, there can be no such "further movement" of a point, to the degree it can transport a point which was in the "inside", to the "outside".
My observations suggest that compression at a bend plays a big role, with the inner / compressed fibres being what break (first).
You had expressed this theory before, but now you use a more careful language : you do not claim any more that it is compression that is the cause of the breakage, as before, but that "the compressed fibres are the fibres that break (first)" - a different thing. It can, indeed, be the case, that the real cause of the breakage ( which, IMHO, is the tension, combined, perhaps, with torsion, NOT the compression ! ) generates a cascade of effects ( elevated temperature due to friction, vibrations due to the enlargement and propagation of already existing micro-cracks, etc. ), and that those effects, for some unknown ( to me ) reason, are especially efficient when they are applied on the compressed fibres. In short, that the compressed fibres are the weak links, in a temporal, spatial, and material chain of complex phenomena - and, as weak links, they break first. Perhaps the compression plays a smaller or bigger role in which fibres break first, but this does not mean that it is the cause of their breakage, as you were claiming till now.
In one case of slippery, HMPE, the break seemed to come well inside, which I credit to the material being able to deliver high tension --w/o mitigation /"off-loading" via friction-- much father along the SPart's path (this seemed to be past the SPart's U-turn, of all things!).
This may be used as an evidence supporting your argument, indeed - but, to my view, it is only an ad hoc effort to somehow fill the GREAT voids of it... This effect can well be explained by a number of other arguments : If friction is low, the amount of temperature that would be sufficient to melt the fibres can only be accumulated further along the Standing Part s path, where it will also be enhanced by some contribution of the temperature generated by friction between other segments of the knot. Also, it may be the case that, in this particular material, sharp bends can tolerated much less than in the case of other synthetic fibres - so the breakage point is closer to the point of maximum curvature, which is located deeper in the nub, not at the "outside". We do not even know if the mechanism of the breakage itself does not depend on the friction coefficient of the rope : perhaps a theory that would be able to explain, and predict with numbers, the breakage of manila ropes, would not ne able to explain the breakage of "ordinary" synthetic ropes - and a theory that would explain the breakage of the very different, very slippery HMPE materials, would also be very different ! Friction is a very complex phenomenon, which is not very well modelled / explained, and this also happens with the effects of temperature on synthetic macromolecules - so we can imagine what happens when we try to deal with both of those problems in one go !
I will repeat here what has made a great impression on me : the exact path of the line in an overhand stopper, even in the case of ideal knots, with perfectly cyclical cross sections and no friction at all, is NOT known yet ! If the mathematics of the most simple knot is not known, we can imagine what happens with the physics !
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In this post I will try to illustrate with another example what may appear as a "knotting magic", but, in fact, it is nothing more than the result of the simple reeving of the whole knot through a bight of it.
At the first attached picture, we see the bight of the eye of a loop, with a slipped overhand knot tied on one ( the "upper" one) of its free ends. The bight which is slipped through the overhand knot in not encircling the pair of the free ends - or, in other words, the pair of free ends does not go through / does not penetrate this slipped bight.
At the second attached picture, we see the SAME knot, where the slipped bight does encircle the pair of the free ends : it has became a collar around those lines. Now, in contrast to what was happening in the previous stage, shown in the first picture, the pair of free ends does go through this collar, does penetrate it. How did this knotting miracle happen ?
No miracle whatsoever, unfortunately : if we are not confused by the tangled wording and the image of the tangled lines, we can easily figure out that, in order to pass from the knot shown in the first picture to the knot shown in the second picture, we have to just reeve the whole knot through the slipped bight, which will now become a collar. Doing this, all the lines of the knot will go through the collar, so, if we will move some of them to the right, what will be left at the left :), the pair of free ends, will now be encircled by the collar.
In the case of the Ampersand bowline, I have described this simple trick with those words :
how on earth will this collar manage to encircle the Stranding and the Tail Ends, which do not penetrate it at this stage?
Piece of cake :) ! By pure knotting magic :) : Just reeve the whole knotted part of the line you have already formed through the ... bight of the collar, so that the two free lines ... will become encircled by it ! In fact, after some time, you will find out that it is much easier to do the same thing the other way - that is, it is much easier to move only the bight of the collar, first "over", then to the right, and then around the rest of the knot, and engulf / encircle it. So, doing this, you will have to move only the "mouth", the bight of the collar, and not what will be "swallowed" by it, the rest of the knot. When this "mouth" will be all around the [knot], just push it to the left, to the side of its final destination.
When we want to transform the geometry of a knot without altering its topology, this simple trick is the easiest and first thing we try. However, I do not know a word / term which can describe it. The interested reader is kindly requested to imagine something.
The procedure reminds me the sequence of moves which turns a glove inside out - perhaps the term "turn the collar inside out" , for the reverse procedure ( the move from the stage where the collar does encircle the free ends, shown in the second picture, to the stage where it does not, shown in the first picture ), would be able to offer a useful mental image of it.
At the third and fourth attached pictures, one can see the same thing in the case of tying the Ampersand bowline in-the-bight. The third picture corresponds to the shape of the knot after stage 3b, and the fourth picture corresponds at the shape of the knot after stage 4, that is, just before the Ampersand bowline is drawn taught in its final form.
That is the reason I had chosen to present this particular tying method, and not another one ( starting from a slipped overhand knot ), which is faster. After we form the twisted three times initial bight ( three times, as one should had memorised by now... :)) and the right-handed nipping loop, and after we reeve the upper part of this twisted bight through this nipping loop, from "under" to "over", we reach to the final stage. All we have to do from now on, is to perform this elementary knotting magic, and make this reeved upper part of the twisted bight be encircled by - and so become a collar around - the free ends.
Imagine we have agreed to use a term for this trick ( if it is possible to agree on anything ! ). I denote this term as : <term?> . Then, to tie the Ampersand bowline in-the-bight, one has to :
1. Twist a bight three times / three 180 degrees turns, clockwise ( righty-tighty ).
2. Form a right-handed nipping loop on the "upper" one of its two free ends.
2. Reeve half of this twisted bight through the nipping loop, from "under" to over".
3. <term?> this reeved half of the twisted bight, to/on/around/ (or whatever proposition describes it better) the rest of the knot.
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Nice presentation, thank you.
1. Twist a bight three times / three 180 degrees turns, clockwise ( righty-tighty ).
2. Form a right-handed nipping loop on the "upper" one of its two free ends.
2. Reeve half of this twisted bight through the nipping loop, from "under" to over".
3. <term?> this reeved half of the twisted bight, to/on/around/ (or whatever proposition describes it better) the rest of the knot.
Using the two pictures from reply #18 and adding picture #4 (Stage 4) Does the trick.
The key is to take the bight of the half twisted, opening it and bring it over the bottom of it all and place it at the collar location, then dress it.
SS
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I had not presented the picture#4 at Reply#18, on purpose : I thought that I had first to show the turned-inside-out-collar trick in a simpler case, and ask for a proper term for it. This reeving of the whole knot through one bight stemming out of it, although it is conceptually elementary, it looks quite complicated in pictures ! Picture#4 seems too complex, if it is not seen as a mere implementation of the trick after the under/over half-reeving of the twisted bight through the future collar.
opening it and bring it over the bottom of it all and place it at the collar location
I do not believe that this is the term you propose... :) What about the "turn a collar inside-out", or "turn a collar outside-in" ? Any other idea ?
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What about the "turn a collar inside-out", or "turn a collar outside-in" ? Any other idea ?
It could work, but it is not quite a collar yet. Turn a to-be collar.... nah.
It is an open bight that has to be positioned in the collar location after it has been pass over the rest of the tangle and I don't know of a term for it yet. It is like what we do when we tie a bowline on a bight that results in a double eye.
http://en.wikipedia.org/wiki/Flype (http://en.wikipedia.org/wiki/Flype)
Bightflyping ? Blyping?
:-\
S
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The term "flype" has already been taken by others, I am afraid...
http://en.wikipedia.org/wiki/Flype
Also, it would be great if we had a term that could describe both transformations : a future, to-be collar turning into a collar, and a collar turning into an ex-collar - even with an adjective, as "reversed", or a negative sign (-), in front of it.
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How about - haltering move?
SS
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Like "haltering the white cow", or like "haltering the black cow" ? :)
https://www.google.co.uk/search?q=haltering+etymology&hl=en&gl=uk&authuser=0&source=lnms&tbm=isch&sa=X&ei=03xlU4zoF4moO-O1gPAF&ved=0CAcQ_AUoAg&biw=1280&bih=642#authuser=0&gl=uk&hl=en&q=haltering+a+cow&tbm=isch&imgdii=_
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My thought is that the inner section of synthetic rope is crushed to a point of high enough temperature to melt, allowing the molecular bonds to release, then the subsequent tensile parts tear.
With natural fibers, it will be the fibers with the greatest tensile strain, the outer ones.
We should not confuse pressure with temperature.
When you do work upon a rope it's temperature may well go up, but heat is mobile. An increase in temperature will cause a heat gradient and that heat will conduct away. If we apply a load gradually, any heat generated will conduct out of the rope. By loading a rope sufficiently slowly, its temperature can be maintained at any chosen value, so heat, i.e. elevated temperature, cannot be the cause of that rope to fail, yet fail it eventually will - but it won't be through temperature melting.
A twist to this argument, is that as you stretch a rope, much of the work done is being stored in the fibres as potential energy. This energy will be released as heat when the fibres are allowed to contract back to their un-stretched length. So, as a fibre breaks and snaps back in length, it suddenly sheds it energy as heat, but that heat is released along the length of the contracting fibre. In this way, heat is released into different parts of the knot than the part where the first fracture occurred. Fibres stretched around an outer radius may be taken beyond their breaking strain and so fail, and then dump their released heat into a different part of the knot as they shrink back under the released tension.
The second and most often ignored aspect of failure is pressure or compression. If you take a guillotine or a knife to a cord, it is the point pressure hugely magnified by the tiny area of contact that ruptures the fibres. All organic fibres are polymers and at some pressure they will flow and deform. It is not heat but pressure that has this deforming effect. However, most polymers are very temperature sensitive. So, if we have a fibre under sever compression, but not enough to cause it to deform, and then suddenly an adjacent fibre releases a load of heat (because it just snapped), then the compressed fibre absorbs some of that heat. If the consequential temperature rise takes that fibre above its flow point, then it too can rupture, releasing it's stored energy as it shrinks back to unload length. Again, the released energy will be 'piped' into other parts of the knot.
The failed fibre, not only releases its stored energy into the cord as heat, it also has two other effects. First, the load it was carrying is now instantly transferred to the remaining fibres. It might only be a tiny incremental increase, but it is an increase, driving all the other fibres nearer to their failure paints. The second and potentially far more sinister effect is that because that fibre has lateral frictional contact with the half dozen fibres around it, it transfers its tension selectively into those fibres, along with its released energy as heat. We now have a tiny bundle of fibres, already under tension, suddenly subjected to an increase in tension and an increase in temperature for some distance away from the break point of the first fibre. Any weak points in those heated, sections under additional tension are likely to fail and so start a chain reaction of failure, heat release and transfer and further localised load increase.
Hence, we should expect to see, and in fact do see, a scattering of fracture points occurring throughout the knot, as a storm of failure fires throughout it, transferring heat, load and pressure into different parts of the cord and the knot. We should also expect to see the 'gross' failure of a knot at some point other than the weakest point that actually initiated the avalanch of failure.
Derek
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Good day Derek.
We should not confuse pressure with temperature.
When you do work upon a rope it's temperature may well go up, but heat is mobile. An increase in temperature will cause a heat gradient and that heat will conduct away. If we apply a load gradually, any heat generated will conduct out of the rope. By loading a rope sufficiently slowly, its temperature can be maintained at any chosen value, so heat, i.e. elevated temperature, cannot be the cause of that rope to fail, yet fail it eventually will - but it won't be through temperature melting.
I understand to a limited place what you've written and can see the point(s) you make.
I don't know how you can have pressure without temperature and perhaps that is my confusion, if I am confused.
Yes, the heat is mobile, I agree, but there seems to be a limit as to how fast the surrounding material can allow the transfer. If it is not fast enough, then there is a build up of surplus heat. It follows, in my mind, that if the surplus is there long enough, the chemical bonds could be effected. What I have read about polymers, this heat can influence the bonds, perhaps weakening them.
I previously posted a link to video of a tensile test involving two Fig.8 eye knots. http://www.youtube.com/watch?v=s3fHYGY3YTo The tester used thermography to view the heat within the knot till failure. The friction and pressure (my term - crushing) heat building does seem to be greater than the the material's ability to allow it to escape quicker than it builds. From this I can hypothetically conclude what I stated.
Perhaps we should not take anymore away from the OP. Possibly start another knot breaking thread? Again.
This eye knot deserves a good deal of scrutiny as it seems to be quite sturdy in many aspects.
SS
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As the "right-handed" Ampersand bowline and the "left-handed" Scot s TIB bowline are the one the "reversed" eye-knot of the other ( here, the "reversal" is referring to the swapping of the Standing and the Tail Ends ), it should had been expected that their "other-handed" forms would retain the same properties / relations : indeed, they are also TIB, and they are also "reversed" to each other. In this thread I had shown only the "right-handed" Ampersand bowline, because I think it is simpler, visually and structurally - and that, as it is a two-collar ( = double collar ) "secure" bowline, it does not suffer from the instability during ring-loading the common, "right-handed" bowline does. The interested reader is advised to tie the "left-handed" Ampersand bowline, too, and convert it to the "right-handed" Scot s TIB bowline, shown at (1)-(2).
{ I would also like to mention here that, after I had "swallowed" and "digested" the TIB tying method of the Ampersand bowline presented at (3), I tie the Scot s cow, sorry, TIB bowline, following the same method - so, I start from a triply-twisted bight, and not from a slipped overhand knot, as JP does in (4).)}
1. http://igkt.net/sm/index.php?topic=4517.msg29939#msg29939
2. http://igkt.net/sm/index.php?topic=4517.msg30269#msg30269
3. http://igkt.net/sm/index.php?topic=4877.msg31923#msg31923
4. http://igkt.net/sm/index.php?topic=4517.msg29687#msg29687
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I always tie the knots I want to study in detail on very soft and on very stiff ropes, to see if they have any drawbacks which I had not noticed, but which may be revealed, somehow, this way. See the attached pictures for the left- and the right-handed Ampersand bowline(s), tied on the most stiff rope I have : its diameter is 11mm, but it should be filled with a peculiar stuff, because the sharper curve I can bent it, between my thumb and my index fingers, can not be less than 2 rope diameters...( but I should say I am no weight-lifter... :))
In the left-handed Ampersand bowline the second leg of the "upper"/first collar follows a curve which turns around the same, always, direction : the "bridge" that joins this collar ( the U-turn around the pair of the Standing and the Tail ends ) and the other, the "lower"/ second collar ( the U-turn around the rim of the nipping loop and the eye leg ), is an almost straight segment. In the right-handed Ampersand bowline, this same second leg of the "upper"/first collar makes an S-turn before it reaches the "lower"/ second collar. This may mean ( :-\ :-\ :-\ ) that, in this S-shaped segment, the differences in the stretching of the "inner' and the "outer" threads at each turn are smoothed out, so the material of the collar structure is used more evenly. I would be glad if I could see, literally, what happens inside the core of the rope at each turn, how the individual threads are loaded, and transfer the various kinds of the forces acting on them along the axis of the rope, and to each other ! :) Is it better to have two U-turns joined by a straight segment, or by an S-shaped segment ? This is a general question, of course, which concerns the "bridges" ( the segments between the two collars ) of all the Janus bowlines, and then some... Only KnotGod knows. :)
However, after I had loaded both eyeknots lightly, with about half my weight, all the O-, the U- and the S-shaped turns had been smoothed out to the same degree ( see the attached pictures ), and this tells me that the there is no great difference in the amount of strain which forces the segments of the rope in the two similar structures to bend - against their will ! :)
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Hi xarax,
As the "right-handed" Ampersand bowline and the "left-handed" Scot s TIB bowline are the one the "reversed" eye-knot of the other ( here, the "reversal" is referring to the swapping of the Standing and the Tail Ends ), it should had been expected that their "other-handed" forms would retain the same properties / relations : indeed, they are also TIB, and they are also "reversed" to each other....
....The interested reader is advised to tie the "left-handed" Ampersand bowline, too, and convert it to the "right-handed" Scot s TIB bowline, shown at (1)-(2).
I had luck in transforming the right-handed Ampersand Bowline in the left-handed Scott's TIB Bowline, and vice versa, but I have not had the same luck in transforming the left-handed Ampersand Bowline in the right-handed Scott's TIB Bowline:the second link(the collar) of the left-handed Ampersand Bowline is (unlike as is the case of the right-handed version) not an un-knot,but is topologically equivalent to an Overhand knot,then I am not able to transform it into the nipping loop of a right-handed Scott's TIB Bowline(and I must say that,despite the fact that both links of the right-handed Scott's TIB Bowline are topolgically equivalent to un-knots,I could not get something similar to an Ampersand Bowline starting from this loop).What I'm missing?
Bye!
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What I'm missing ?
Nothing ! :)
First, I should better re-post something I said some time ago, although in a more restricted sense :
When the Tail end penetrates the nipping loop ... it can follow more than one distinct paths, because it can go "over" or "under" the returning eye leg, and perhaps " over" or "under" further continuations of it, that have already gone through the nipping loop. The interesting thing is that, regarding the TIBability, the particular path the Tail end follows through the nipping loop does not matter: the resulting eyeknot is always TIB.
So, regarding TIBability, the particular path the second leg of the collar of the "left"-handed Ampersand bowline follows through the nipping loop does not matter : the resulting eyeknot is a TIB, in both cases.( See the attached picture, where, in the red circle, we see the second leg of the collar going "over" the first ).
I had shown the "left"-handed bowline in its one form, where the second leg of the collar passes "over" the first, for three reasons : 1 : because I think that so it is tied in-the-end in a more straightforward way, that is, more easily/quickly. 2 : because that this way the second, "lower" collar becomes wider, as it goes around the returning eye leg, so it encircles three rope diameters. And, 3 : last but not least, because, during ring loading, I believe that, this way, the nub will remain more coherent and compact, so it will behave better.
Those advantages, and the fact that both knots are TIB, had lead me to show this form and not the other, where the second leg of the collar goes "under" the first - and where this "second link" of the knot, this "collar structure", remains topologically equivalent to the unknot. Strictly speaking, the other form is what should be named as "left"-handed Ampersand bowline, corresponding to the "right"-handed Scott s TIB bowline - but I though that this almost negligible, geometrically, difference was not worth the loss of the advantages I had described above, and the trouble to explain all this. Well, in that last, it seems that I was wrong ! :) I am glad you had noticed it and you had offered me the opportunity to clarify the matter - as you always do ! :) Thank you.
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In this particular case of the two forms of the "left"-handed Ampersand bowline, we KNOW why they are both TIB : to tie them in-the-bight, the only thing we have to change, in relation to the TIB tying method of the "right"-handed Ampersand bowline, shown at (1) and at the attached picture,, is the twist of the collar. In the "right"-handed Ampersand bowline, the bight that will become the first/"upper" collar should not be twisted. In the "left" handed Ampersand bowlines we have to twist it 180 degrees clockwise or counter-clockwise. If we twist it towards the one or the other direction, the second leg of the collar goes "over" or "under" the first. So, both eyeknots, tied in-the-bight this way, are TIB, and we now know why.
I believe that this "proof" can be generalized, and we can always justify the observation about the TIB ability of both forms of the TIB bowlines described in the previous post, because the two bowlines that we want to know why they are both TIB, can always be tied in-the-bight by a similar tying method, where only the orientation of the twist of the bight that will become their first/"upper" collar will change.
1. http://igkt.net/sm/index.php?topic=4877.msg31923#msg31923
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A picture of the two forms of the "left"-handed Ampersand bowline, tied on my most stiff rope. Regarding their differences, one can distinguish the slightly wider second/"lower" collar of the knot at the right ( where the second leg of the collar goes "over" the first", so this collar encircles three rope diameters ), but not much else. If it is anticipated that the eyeknot would be ring-loaded, I would prefer the one shown at the right - although it is not the corresponding to the "right" handed Scott s TIB bowline. Perhaps another reason is that this was the form I was tying right from the start, because it looked more streamlined and coherent, before I discovered the correspondence...
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Hi All, Xarax no longer here, his works and contribution still here with us, I like his well secure Ampersand bowline,
I have a quick way to tie these knots, see you guys like it or not ?
alanleeknots at YouTube.
謝謝 alan lee.
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I like his well secure Ampersand bowline,
Why?
I don't like it, for from-the-start separating the crossing
of the nipping loop, such that it begins loading already
halfway into a (significant) helix vs. contracting circle.
(And with soooo many other bowlinesque eyeknots to
choose from, why ... ? !!)
--dl*
====
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Hi All,
Dan, you have said "soooo many bowlinesque to chose from" can you please show me some of them,
are they PET and TIB knot ?
Xarax already described some advantages of the Ampersand Bowline in here" http://igkt.net/sm/index.php?topic=4877.0"
see if you can find anything you like, if you happan to find something you like, Please share it with our reader,
of cause incleded me.
Oh, Just about to foget to asK you, Do you like the way I tie this well secure Ampersand TIB bowline?
謝謝 alan lee.
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Hi All, Xarax no longer here, his works and contribution still here with us, I like his well secure Ampersand bowline,
I have a quick way to tie these knots, see you guys like it or not ?
alanleeknots at YouTube.
謝謝 alan lee.
Thanks for the good work Alan.
I find your tying of it ingenious and I salute you for working hard to come up with a way. It is not so simple unless one practices and memorizes it.
That said, I personally don't find a need, very often at all, for tying eye knots in the bight. I generally need to thread the rope through something and then finish tying.
But, it is good to know for the sake of knotting information nevertheless.
Thank you.
SS
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Hi All,
Dan, you have said "soooo many bowlinesque to chose from" can you please show me some of them,
are they PET and TIB knot ?
Xarax already described some advantages of the Ampersand Bowline in here" http://igkt.net/sm/index.php?topic=4877.0"
Somewhere on this site there is the presentation of the
simpler-than-Yosemite Bwl like version (the YoBwl has
a fig.8 tail path; the "simpler than..." an overhand one,
which is PET/TIB.
The obvious case is just tying the bowline with a bight from
the tail, giving sheet bend geometry for *through* loading,
but not offering eye-loading of the tail (not decently, anyway).
Xarax's
A bowline-like PET loop is a versatile and a useful knot
--so a TIB PET loop, is even more versatile, and at least as useful as a non-TIB one.
It would be great if we could discover and tie the same ONE knot ( instead of tying two different knots )
either when we want/need to tie a loop in the end of the rope,
or when we want/need to tie a loop in the bight, in the middle of the rope
--provided, of course, that we do not jeopardise the qualities required from
the different knots we are accustomed to use in each of the two cases.
should raise one of the issues re What is a *knot*? in its "same"
--to wit: Is it "same" if made by different tying algorithm? Because if
one must do something different when TIB vs. PET, one might as well
be finishing differently, IMO (but for some assertion of great simplicity
in resulting in the same geometry to check for correctness) !
Note that the bowline tied w/bight of tail can use the single tying
method.
--dl*
====
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Hi All,
I know I am the worst one in the forum,I have hard time try to follow words to tie knots, I try and try, and try, eventually I give up.
I hate wasting time on this issue, for all the hours I waste, I would have use it to do some more constructive thing for myself,
or may be create another new way to tie a some knots. 謝謝 alan lee.
VERY SAD, WE COME HERE TO TIE KNOTS, WHY NOT HAVE SOME PICTURE OF KNOTS.
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hi Alan
VERY SAD, WE COME HERE TO TIE KNOTS, WHY NOT HAVE SOME PICTURE OF KNOTS
Same here, I understand you; less words more pictures and btw thanks for yoursl!
Regarding TIB'ness maybe a member with enough time to spare would be kind and commence a post in containing ONLY TIB structures and ONLY post with photos; that would be marvelous.
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Hi All,
enhaut Thanks for the positive and constructive comment.
I like your idea, nice to have few places just to post picture knots for different category knots.
謝謝 alan lee.
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Hi All,
Dan, you have said "soooo many bowlinesque to chose from" can you please show me some of them,
are they PET and TIB knot ?
Xarax already described some advantages of the Ampersand Bowline in here" http://igkt.net/sm/index.php?topic=4877.0"
Somewhere on this site there is the presentation of the
simpler-than-Yosemite Bwl like version (the YoBwl has
a fig.8 tail path; the "simpler than..." an overhand one,
which is PET/TIB.
The obvious case is just tying the bowline with a bight from
the tail, giving sheet bend geometry for *through* loading,
but not offering eye-loading of the tail (not decently, anyway).
Xarax's
A bowline-like PET loop is a versatile and a useful knot
--so a TIB PET loop, is even more versatile, and at least as useful as a non-TIB one.
It would be great if we could discover and tie the same ONE knot ( instead of tying two different knots )
either when we want/need to tie a loop in the end of the rope,
or when we want/need to tie a loop in the bight, in the middle of the rope
--provided, of course, that we do not jeopardise the qualities required from
the different knots we are accustomed to use in each of the two cases.
should raise one of the issues re What is a *knot*? in its "same"
--to wit: Is it "same" if made by different tying algorithm? Because if
one must do something different when TIB vs. PET, one might as well
be finishing differently, IMO (but for some assertion of great simplicity
in resulting in the same geometry to check for correctness) !
Note that the bowline tied w/bight of tail can use the single tying
method.
--dl*
====
Can any one please help, I want to know what kind of knots are in the writing above.
謝謝 alan lee.
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Hello Alan.
I am sorry that I can not help with this. Perhaps Dan will clarify.
SS
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Hi All, Scott, Thanks for the reply.
謝謝 alan lee.
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Somewhere on this site there is the presentation of the
simpler-than-Yosemite Bwl like version (the YoBwl has
a fig.8 tail path; the "simpler than..." an overhand one,
which is PET/TIB.
Hi Alan,
I think Dan was referring to his Lehman's Locked Bowline (I think you know it)
here it is
(http://igkt.net/sm/index.php?action=dlattach;topic=4476.0;attach=11925;image)
(http://igkt.net/sm/index.php?topic=4476.0)
The obvious case is just tying the bowline with a bight from
the tail, giving sheet bend geometry for *through* loading,
but not offering eye-loading of the tail (not decently, anyway).
Perhaps he was referring to ABoK #1016...
(http://igkt.net/sm/index.php?action=dlattach;topic=5593.0;attach=20267;image)
(http://igkt.net/sm/index.php?topic=5593.msg37984#msg37984)
[edit] but this is not PET!? :-\
Hope this helps.
Ciao,
s.
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Hi All, knotsaver, You have a great day, Thanks you very much.
謝謝 alan lee.
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Thanks for finding ...
Indeed, it was the top (rather, um, *wavery*) knot.
Note that this can be tied by inserting a bight tip
into the nipping loop, then "backflipping* it into
final, collaring position --there are 4 orientations
(or more) to this, and I think the one shown might
be best (and can be loaded on either end).
This particular bowline was presented decades
ago by Pieter van de Griend & John Smith in Knotting Matters
(#18, is it?).
--dl*
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