Author Topic: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't  (Read 1436 times)

SS369

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #15 on: January 18, 2020, 10:51:50 PM »
Thank you Dan for your most excellent sleuthing and criticizing.
Regardless, the only reason I injected the link was to add another interesting investigative method that could be of value to further knot force understanding.
Whether the tyers and video makers got something incorrect, according to you, at least they invested time , etc.
I guess you could leave your comments on their YouTube channel.

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #16 on: January 21, 2020, 07:15:36 PM »
... sleuthing and criticizing. ...
//
... you could leave your comments on their YouTube channel.
Firstly, I cannot, and don't want to create a special account
just to post a comment.  Others who might already be in a
position to do so are hereby invited to post my summary
below (you can refer to the IGKT forum as the source).
It would be interesting to see any follow-on comments.

Still going on.  <sigh>
At this point, I see things as follows:
0:20 shows START orientation, well enough (vis-a-vis
   knots' tightening) to see TOP knot as *interior-loaded*
   --note how the uppermost, eyeleg-surrounding part is
      left untensioned--
   and BOTTOM knot as *exterior-loaded*
    --the telltale compression of SPart into its twin,
       pushing this part wide.

   AND TOP eye legs cross UNDER, SPART crosses OVER
   the parts turning around them;

   SAME upper/lower UNDER/OVERs for BOTTOM knot, but as
   it faces downwards its SPart & tail X UNDER, eyelegs OVER
   --and the big ring around which eye is tied looks to be the
   most position-stable structure of the system.
   .:.  knot bodies should remain pretty consistent in orientation.

Now, at 0:26 we have our 1st thermal image (but no heat #s);
per knot shape it matches the *exterior-loaded* BOTTOM knot
BUT is showing OPPOSITE FACE (SPart crossing OVER?!).

(So, where is this thermal imaging device?!  We see only
a blank white-ish wall behind our view from video camera?!
Have they gotten a later-after-changed-positions image?!)

At 0:41 we have a 2nd thermal image, of a narrow and
indiscernable knot blob which perhaps is consistent with
the TOP knot (*interior*-loaded), but it's really hard to say.
Heat #s "23.7" at peak point.

At 0:45..51 we see the BOTTOM knot BUT OPPOSITE FACE
--SPart & tail Xing OVER, and bulging-wide twin part now
continuous before us, Xing w/tight SPart over eye legs
so which are crossing UNDER, newly?!
Has the knot been already flipped to top but image reversed?

Contrasting w/above, at 0:53 the new thermal image
(with heat #24.1 at peak area) is flipped upside-down,
and shows opp. face (now broken wide twin part as it
crosses UNDER eye legs now pointing upwards) to just-seen
(0:45ff) video of knot!?

And if one is QUITE DELICATE in advancing video images,
somewhere around 1:00 :xx there is the momentary glimpse
of the orange hook, biased to viewer's right (i.e. near part of
hook), w/o any 'biner, holding this once-at-bottom knot
(w/faces as in just seen thermal image, SPart Xing UNDER,
upper/eyelegs OVER the turning parts.

At 1:11 is a thermal image of knot immediately pre-rupture,
heat #27.1 at peak.  I guess that this image is shot looking
downwards, as tail looks shorter and the bulging part more
fully around ... than in the video's more perpendicular view?!

YET, in sharp contrast, at 1:19 we see a thermal image
--one brief view prior to "BREAK 1820" pasted across it--
an (1) OPPOSITE FACE (bulging part now unbroken, crossing
over all) and (2) eye facing DOWNwards.
THIS IS THE OPPOSITE FACE TO THE STARTING VIEW.


Okay, I hope that does it.
--dl*
====

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #17 on: January 21, 2020, 07:38:59 PM »
I should add that the final video images of the broken
rope show a knot much less distorted than in the test
under compression --which I assume is unexceptional
(i.e., the real rope seen).  Which points to how elastic
nylon is, and makes one wonder how a low-stretch
(Sterling HTP, e.g.) polyester rope would fare : same
loading but now w/material doing different things under
that load, and ... what follow-on significance that has!?

And we should also wonder where the break occurs
in the *interior*-loaded knot, or for that matter in an
*exterior*-loaded one dress & set per my method noted
above, where one tries to keep that born-into twin part
from being pushed wide-aside as it was here.

The break here looks pretty clean/sharp/limited-in-length
(with maybe some slight extended damage on what was
the concave side bearing upon other parts).

 - - - - - - - - - [added 1/22 Wednesday] - - - - - - - -

And I meant to remark at the bottom anchor of the
testing device, which is stabilized somehow with bungee?
cords left/right, and able to rise a little during the test?!
I wonder if this is to be somewhat more realistic of actual
breaks, where load doesn't pause for some constant-distance
movement but continues the force on the structure!?  I also
wonder how the knot is put around the ring,
for we have the upside-downing to explain and all ; the ring
looks large for that 'biner to just clip to!


--dl*
====

ps : Still no reply from the Science article's Corresponding
Author --not (yet) corresponding w/ME!  --I asked about
the specifications of the only symbol-ID'd knots, and of
the "20mm" rope size for those images which impressed
me more as *cord* and nearer thus to 2.0mm.
« Last Edit: January 23, 2020, 01:04:48 AM by Dan_Lehman »

KC

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #18 on: January 25, 2020, 12:49:01 PM »
In any case, views into an inner world not had before; or at least to such confirming depth of tuning other observations towards.
Like microscope, thermal imaging, magnetic film, xray, colored forensic lighting etc.
.
i wouldn't take first views as total story, perhaps not even contiguous here; but rather promises of where can go with this.
As data from this stacks over time, if they could keep on it;
consistencies to confirm or refute present views would have to be revealed.
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.~

Dan_Lehman

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #19 on: February 12, 2020, 02:22:33 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).

[STILL NOT ANSWERED]

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*
====

I see a UKClimbing view into this which has more
knot indications, though I don't find an answer to
my above query --except that in this view below
the "bowline" is clearly NOT but rather a sheet bend
(and other loadings, but always just 2 not 3).

www.ukclimbing.com/articles/features/knot_theory_in_practice_-_studying_the_mechanics_of_knots-12570


--dl*
====

KC

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Re: Color-Changing Fibers Reveal Why Some Knots Hold And Others Don't
« Reply #20 on: February 12, 2020, 12:19:21 PM »
Very Nice!

To me Sheet has similar form, but with different loading
>>like similar road with different traffic load/patterning thru that road that can need different approach and handling
>>no matter what eye says, the 'thermal photography' of traffic loading is like fish, insect or other animal seeing infra red or a smell we don't
>>as blinded by our own non-force based, 'colder' vision of physical not force  patterns
>>and even forensic lighting can give more clues to what we miss in own paradigm
.
>>But same 'Killick' on right angle pull puts HH wrap on host in force line and is tighter more like 'Kelleg' around anchor stone than lengthwise spar hang.
.
Sheet Bend HH lock is tighter like that of Sheep Shank, these lay into the force line of the rest of the rope pull
>>these lay flat into force line, not at right angle like Bowline and HH preceder on lenghtwise pull
.
You can change Bowline Nipping Loop to more lay into force line by 'faux' extension of the stiff collar to looser
>>just as can reeve loop(s) of Sheep Shank and tighten 1 collar and it's Nipping Loop softens as turns away from force line,
>>as the looser collar allows at same time/load/materials for the HH/Nipping Loop to lay flatter, under more tension into the force line
.
HH termination is single end pull, different than dualed HH as pass thru
>>of (to me) HH's back to back sharing same central termination point, serving out then 2 ends, not one
HH dualed pass thru especially loads different, when is held at right angle
>>out of the linear flow of force down the mainline proper
As a preceder can convert knot meant for right angle pull (Timber etc.)
>>To perhaps lengthwise pull capability
1st words in pre-ramble for Chapter_21 lenghtwise pulls, starts with Killick example of converting from standard right angle pull
"To withstand a lengthwise pull without slipping is about the most that can be asked of a hitch. Great care must be exercised in tying
the following series of knots...."
>>It intros Killick 1st, after previous chapter showing Timber as right angle of proper pull example (only HH precedes it in chapter)
.
There is a lot we don't know/see of this inner world; as have chased microbes and sea to see those inner worlds.
>>i hope this new tool will grow to show many things and turn on many lights of understanding.
quantamagazine.org/color-changing-material-unites-the-math-and-physics-of-knots-20200210/

.
i always visualize some passing of load force across friction points as alternate routing
>>thus not all running trace of full deformity to pass force, but rather shortcut around some with part of force
« Last Edit: February 12, 2020, 12:22:12 PM by KC »
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.~