Author Topic: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't  (Read 1618 times)


SS369

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #1 on: January 04, 2020, 02:41:00 AM »
Nice find, thank you.
I wish I had some of that cord.

I am wondering if the use of the words ?strength and stronger? are not quite what they are indicating in the papers.
My takeaway is that they are perhaps implying better security.

SS

alpineer

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« Last Edit: January 04, 2020, 03:29:19 AM by alpineer »

alpineer

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #3 on: January 04, 2020, 06:26:56 AM »

I am wondering if the use of the words ?strength and stronger? are not quite what they are indicating in the papers.
My takeaway is that they are perhaps implying better security.

SS

The article's wording does appear ambiguous, but I would agree with your interpretation.

Olegan67

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #4 on: January 04, 2020, 07:42:10 AM »
This article is certainly interesting. Knots can be considered by physics and mathematics, so sailors and mountaineers are very interested in certain types of knots, and separately they are tested on a tear test. And of course, from a practical point of view, it is necessary to know where the knots is used. :)

KC

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #5 on: January 05, 2020, 10:37:15 AM »
Very interesting even exciting!
.
Usually i'd like calling the Reef by original name, rich sea heritage and salty roots.
But, to me, faults of Thief, Granny, Grief all stem from arrangements that pull out of the flat square form to de-stabilize.
The 'SParts' of Thief actually pull the shape form the Bitter Ends to diamond/out of Square as full force pulls the free ends
The 'SParts' of Granny stay flat Square while Bitter Ends side rotating 90degrees and destabilizes from the flat Square profile .
The Grief carries both out of Square faults.
All knots , as any other mechanix, must be held squarely to task to work,
especially a flexible/flimsy device of power!
.
i really think that is what they were trying to pass down unspoken in the name Square;
from a rough world with little text for these things before ABoK;
and closer to these very things seen in many things as common, that we have lost sight of.
At least, for me, i keep the word Square, as a reminder;
of the amount of 'Square Lessons' i see in this simplest joining of ends that carry thru all knots.
.
Simplest things on the cusp of fail have the fewest moving parts to examine but still can work;
also, if can find line between can and can't/fail or not; and what makes that difference/flips the switch, can be very defining to all.
The Square family does that for me, faults included!
.
This new toy will show secrets not seen before thru it's viewport into secret world inside knots.
>>Another toy i've always wanted to have is a Nip Meter, for pinch rollers to make sure huge presses etc. are even pressure all the way across etc.  Expensive, but could show difference in pressures between rope turn and host at different positions for different insights into this world.

Rope-n-Saw Life
"Nature, to be commanded, must be obeyed" -Sir Francis Bacon
We now return you to the safety of normal thinking peoples.
~ Please excuse the interruption; thanx -the mgmt.~

SS369

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #6 on: January 05, 2020, 04:24:48 PM »
I've posted this video before and think it appropriate to link it here as well. https://www.youtube.com/watch?v=s3fHYGY3YTo
With thermal imagining there are color changes seen in loaded knots.
I wish someone(s) with IR camera and load cell access would do a series of different knots.

SS

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #7 on: January 08, 2020, 02:51:33 AM »
I've posted this video before and think it appropriate to link it here as well. https://www.youtube.com/watch?v=s3fHYGY3YTo
With thermal imagining there are color changes seen in loaded knots.
I wish someone(s) with IR camera and load cell access would do a series of different knots.

SS
Thanks much for this (which I don't recall seeing previously
(I do miss things, alas))!

It's a shame that they (1) aren't explicit about their
using BOTH "perfect forms" --*interior- & exterior-loaded*
forms-- in this test, resp. upper & lower (which breaks).
And (2) they are confusing in their flipped-upside-down
presentation of the lower knot, sometimes (flipped).

IMO, if the form that broke IS really the one that CAN
be stronger, it will be so by setting the knot HARD with
the tail, to install the tail's twin part to the SPart such
that it will not so easily be pushed aside as we see
here --that the SPart will at least for some significant
rise in force bear into this twin (whereas in the other
form, the interior strand SPart pulls away, and leaves
its twin so obviously unloaded sticking out almost
like another, small eye!).

(Someone w/YouTube membership is encouraged
to echo these observations into on-line view.
)

--dl*
====

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #8 on: January 11, 2020, 09:09:56 PM »
I've posted this video before and think it appropriate to link it here as well. https://www.youtube.com/watch?v=s3fHYGY3YTo
With thermal imagining there are color changes seen in loaded knots.
I wish someone(s) with IR camera and load cell access would do a series of different knots.

SS
Thanks much for this (which I don't recall seeing previously
(I do miss things, alas))!
...
BUT I ALSO --sooner but often later-- SEE THINGS
(which others miss).
--to wit:
???!
I must comment that the reference video above
apparently is assembled footage,
as the clearly seen Fig.8 eyeknot versions
 >>> and color'd or not metal hook/ring the are attached to <<<
CHANGE during this video.
To begin, the upper knot connects into >>a carabiner<<
and that 'biner into a big ORANGE HOOK,
and the bottom is tied into a metal-grey ring;
   and the versions --interior- / exterior-loaded-- of Fig.8 eyeknots
   are clearly seen in, resp. top/bottom, separation of twin
   parts (interior SPart pulls away from twin, leaving it so
   obviously unloaded at top of knot, towards the eye),

   and hard compression by exterior SPart into its twin
    pushing it wide aside, in the bottom (initially!);
BUT
 just at the 1:00 mark, there is a jitter in the camera
and a BRIEF GLIMPSE of the >>exterior-loaded<< knot
connected >>directly<< into the orange hook (no 'biner)!!
(Re this "jitter" : I saw it initially, then on review did NOT
 see it, then enlarged to full-screen and with video stopped
I was able to frame-by-frame-like get the orange hook into
a stopped frame-image --YES, it is there (and no 'biner),

for the exterior-loaded, soon-to-rupture, knot!).

.:.  My guess :: the testers, seeing both the knots and
the read-out of resp. heating, sensed that it was the
exterior-loaded knot AT THE BOTTOM that was going
to break, and
they then stopped the loading and
reversed the setting, so that this knot was at the top
,
IN VIEW OF THE FIXED-SOMEWHAT VIDEO CAMERA.


(Why is is sooooo damn hard to get **facts** about knots?)

--dl*
====
« Last Edit: January 11, 2020, 09:22:57 PM by Dan_Lehman »

SS369

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #9 on: January 12, 2020, 03:31:41 AM »
Yes, I am sure that they edited and sequenced the video. It may have been a very long one. To me, it is of no importance considering firstly that I could not have done it. Secondly, the information is there regardless of the editing and imo the salient points of the thermal images show to be valuable.

I believe if there are going to be comments about the shortcomings of another's tests or demonstrations, then I propose that someone establish the perfect test scenario(s), submit them and the specimens (tied just the way they want them) and beg (or pay)that the tester provide the time and equipment.

To the point: Anything that can allow the interested persons to examine what takes place within a knot's structure, especially an "in play" knot, is extremely useful.

Thermal imaging, color changing fibers, memory yarns, 3d software, etc., all very interesting.

A big Thank You, to those who have invested and performed these!

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #10 on: January 12, 2020, 10:01:53 PM »
Yes, I am sure that they edited and sequenced the video... .
 To me, it is of no importance
 considering firstly that I could not have done it.
 Secondly, the information is there regardless of the editing
 and imo the salient points of the thermal images show to be valuable.
/.../
To the point: Anything that can allow the interested persons
to examine what takes place within a knot's structure,
especially an "in play" knot, is extremely useful.
???
This is silly :: deceptive / misleading "information" is NOT
helpful but harmful.  That is why I bothered to post the
CORRECT view of what was happening in the video,
so that viewers --possibly even those conducting and
otherwise associated with the very test-- can know
what DID happen, and not think something false.

--dl*
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SS369

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #11 on: January 12, 2020, 11:22:30 PM »
Why would seeing a video of a thermal image showing the heat generated in a knot, of any kind be silly??
Is there no merit or value to this?
Why would anyone say "silly, deceptive, misleading" to a fellow interested knot tyer?
What is the point of such a response? Does it further our knot forces understanding?
So what that they edited the video. I feel that they did not do it to push some hidden agenda. Perhaps to better reveal what they wanted to show? The internal heat stress on a particular knot?
IMO, the changing from a biner to the large hook did not influence this particular test indications enough to call it "silly, deceptive, misleading".
Really...

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #12 on: January 16, 2020, 02:06:29 AM »
Why would seeing a video of a thermal image showing the heat generated in a knot, of any kind be silly??
///
IMO, the changing from a biner to the large hook
did not influence this particular test indications
enough to call it "silly, deceptive, misleading".
Not what I said.  The assertion that flipping a test
specimen upside-down w/o explicit notice of this,
and thereby potentially misleading an interested
viewer into believing that Knot_Upside broke and
Knot_Downside *won* when in fact it was that
Upside was Down
"is of no importance" --what you said--
is silly.
For those of us paying enough attention
--and I wonder if the test team had done so
  (I'm guessing that they DID deliberately
   load one and the other ends)--
to see that we had different knots under strain,
by the clear-cut indications of the knot deformations
early (prior to their becoming supertight bundles
less readily discerned of such details),
it is of much importance.
And, heck, if indeed they were knowingly putting
the two obvious --though seldom discussed-- loadings
of the common knot to test, point that out!
(Were it an accidental doing, one can of course
understand that it wasn't known/cited.)


Quote
Is there no merit or value to this?
To the thermal imaging, yes, it looks "cool"
--ah, the irony in that!  Might we consider
then that there is potential advantage to
broad curvatures or --as CWarner put it--
extended/non-concentrated *nip* partly
for enabling heat to be distributed and
less weakening?!
(Is there some paradoxical aspect in that
where one has extended nip one also has
more cordage movement (and frictional heating)
--like a longer fall having more kinetic energy/force
but also more rope to absorb ... ?!)

It strikes me as though the heated parts
shown are not in (full) agreement with those
"strain"'d parts shown in the Science-pub'd
article, which all come at curvatures (and
which significance I'll suggest is more for
a single fibre than for a composite rope,
whose parts take various placements.
And, regardless, that *strain ain't everything*
re failure --to my seeing, breakage comes
on concave not convex side of curves.

Quote
So what that they edited the video.
I feel that they did not do it to push some hidden agenda.
Perhaps to better reveal what they wanted to show?
Yes, quite :: as I said, they likely saw by eye and
by thermal indications that the one knot was more
likely to fail --they got the Hot Knot, Scott-- and
so put it up where the lens aimed (better).

Quote
Really...
;)

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #13 on: January 16, 2020, 02:20:51 AM »
Incidentally, concerning the Science article,
I sent a query to the "corresponding author"
about what all of the cited knots were (in the
3D graph on p.74? which plots vs. 3 aspects).

There are the known knots:
Re (Reef)
Gy (Granny)
Th (Thief)
Gf (Grief)
then come knots each with a subscript "A" & "B":
[NOT SURE I HAVE THE FIRST 2 A/Bs CORRECT
 TO WHAT IS GIVEN AND WHAT IS NOT --I KNOW
 THEY SHOW ONE WITH A & ONE WITH B, THAT'S ALL.]
Ze-B (Zeppelin as is commonly shown)
Ze-A ?!
Ab-A (Butterfly as is commonly shown)
Ab-B ?!
As-A/B ?! (I guess "Ashley's Bend (#1452)" but two?)
Hu-A/B ?! (I guess "Hunter's Bend (#1425a)" but two?)
Bo-A/B ?! (I guess eyeknot "Bowline", but two?)

.:. 8 unspecified knot designations.
I've guessed on Hu, As, & Bo but cannot produce
two versions for them (surely; I know diff. versions
but these aren't of common reference);
I imagine that our "False Zeppelin" is included;
but not what the 2nd Butterfly would be (unless
it's that non-interlocked_OHes thing); the Bowline
could be "right/left-handed" knots --or not.

Am yet awaiting reply.


--dl*
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Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #14 on: January 18, 2020, 06:35:10 PM »
Why would seeing a video of a thermal image showing the heat generated in a knot, of any kind be silly??
///
IMO, the changing from a biner to the large hook
did not influence this particular test indications
enough to call it "silly, deceptive, misleading".
Not what I said.  The assertion that flipping a test
specimen upside-down w/o explicit notice of this,
and thereby potentially misleading an interested
viewer into believing that Knot_Upside broke and
Knot_Downside *won* when in fact it was that
Upside was Down
"is of no importance" --what you said--
is silly.
For those of us paying enough attention
...  [1/18 :: IT IS WORSE THAN I THOUGHT --SEE BELOW.]
Quote
Is there no merit or value to this?
To the thermal imaging, yes, ...
Quote
So what that they edited the video.
I feel that they did not do it to push some hidden agenda.
Perhaps to better reveal what they wanted to show?
Yes, quite :: as I said, they likely saw by eye and
by thermal indications that the one knot was more
likely to fail --they got the Hot Knot, Scott-- and
so put it up where the lens aimed (better).

Quote
Really...
;)

THE "WORSE" PART :
At time-image 0:52 we are looking at the
initially at bottom, exterior-loaded knot
and then ITS thermal image is presented (0:53)
in upside-down/top-knot-like orientation??!
AND THE THERMAL IMAGE IS FROM THE >>AWAY<<
SIDE to the viewer (note e.g. crossing of the pressed-wide
unloaded twin to the SPart --crosses OVER / under depending
on which-side viewing).
How VERY misleading.  Yes, it is the knot just
seen in plain rope, but one would not realize this
--nor map the thermal image correctly onto the
 rope-shown knot (as eye/Spart+tail sides are NOT
 so obvious!)-- so as to comprehend where the heating
is going on the most (which is as we'd expect where
the SPart tightly wraps the eye legs).

So, it's not merely that they at some time DID swap
the locations of the knots --evidence, the missing 'biner
initially connecting top knot (then >>interior-loaded one<<)
to orange hook--,
but that in immediate sequence imagery (per video timing)
there is this vertical AND front/back reversal !!!
(Which must've come by video display and not physical movement,
else that heating would be lost/diminished.)

ORRRR, maybe --noting changes that DID occur physically--
there is additional confusion in editing IN the (separate device)
THERMAL imagery, and that of final "break" should go with the
rope image of 0:52 --they now do match in orientation-- and
that of 0:53 belongs at the finish, as it matches that flipped-up
state of the knot.  (Though then we can wonder at the shown
>>values/figures/temperatures<< that are with the thermal
imagery : maybe those are edited into image and done so
wrongly --well, the values are at right points but the images
wrong, as just noted.

.:.  Scott, there is a lot of close-scrutiny expert analysis
just done here by me (IMO) which all is nice
(eventually figuring things out (or so I think)),
but all of which should NOT be needed,
had the testers done their job correctly !!
And absent seeing things correctly,
the test video misleads.

?!

--dl*
====