Dyson 4000

This is an awfully long thread for something that as far as I can tell is not for sale anymore.

Or for something that probably was never for sale in the first place. :)

I disagree. While I don’t know it as fact, I believe it is: under longitudinal tension, the tunica behaves much like a Chinese finger toy, elongating by means of fiber re-alignment in the direction of stress thereby achieving strain relief. The effect of this is minimization of total strain delivered to the total length of tissue stressed, with two maxima, one at each attachment point and one minima, at the midpoint between the two maxima; a graph of the strain distribution would look like a low amplitude parabola. With the (non-existent) Dsyon 4000, one achieves multiple shorter parabolae, thereby allowing for delivery of a larger total strain along the total length of tissue for the same total stress applied. As a cherry on the icing, due to interaction of strained volumes on either side of the interior attachment points, constructive interference, i.e. tissue on either side of the interior attachment points being pulled away from each other, higher amplitude parabolae of strain distribution would result.

But I could be wrong :) .

xeno

By tension’s definition, it will be equal. The parabola you are speaking of do happen but it produces fluctuating stresses. This will be a function of the tension between two points and the distance between those points.

Ok, let me explain this better. If you take a rubber tube and stretch it with a constant force (attach one end to the ceiling and apply a weight to the other) the tube will narrow towards the center, reaching its most narrow point exactly halfway between the two points. Just like the finger trap example. Because stress is calculated as force (tension) divided by cross sectional area, and the exact middle has the lowest diameter, it will have the lowest CSA and, therefore, the highest stress. That is why if you stretch a rubber band (assuming no imperfections) it breaks in the middle. This decrease in CSA, however, is a function of the distance between the two points, the ceiling and the weight in my example. As this distance becomes shorter, the narrowing at the center (decrease in CSA) will decrease proportionately. So by securing at multiple points tension is still always equal, but you do create more parabolas (areas where narrowing occurs), however each parabola’s amplitude will be decreased proportionately and average stress will be equal.

So essentially what this creates is several low stress points as opposed to one big one.

I just found this example where an aerospace engineer is explaining the relationship between tension and stress, probably better than I did. :)

You’re not considering this rootsy.

xeno

I can’t imagine the inner clamps could hold tight enough to their respective attachment points without causing severe circulation issues, to impact the overall stress in this way.

:) It’s sure got the bro-engineering ball rolling.

I am not so sure about that. The clamp (noose or strap) in a conventional extender has to stretch the whole shaft and seems to work OK without severe circulation issues at least for 60 minutes. By distributing the clamping and stretching along the shaft this one should be better. I suppose the ultimate example would be an Xsleeve which effectively clamps and stretches continuously along the shaft albeit at a low tension and compression.

Yea, that could be a problem. If it was, perhaps the device could be used as a ‘punctuated’ stress applier, delivering a lot of stress for a short amount of time…kinda like dynamic pumping to high vacuum for a short period of time. In this context, if followed by CC use in the micro-P phase, it would be part of a most excellent IPR concept conforming tissue training protocol.

Is starting to seem a little silly discussing this non-existent thing…but maybe some talented and entrepreneurial sort of cat will pursue building one; I rather think that you would be an ideal person for the task cantlook…I volunteer to beta-test :) .

xeno

I saw the number of hits and posts on this thread and thought WTF! So I was going to make a comment much like yours. :shrug:

Most great ideas don’t start as great ideas. Sometimes great solutions really do start as a joke and it tweaks something in someones mind.

I think it’s great to see everyone who is chiming in even if it is all because of a ridiculous (in my opinion) product. Might inspire someone to build something… can’t promise it will be me though. :)

Well, this is just the beginning. The plot will come out.

Maybe. When we get into biology it is hard to say what is going to happen in every situation. My analysis was only based on physics.

This is what I can say about tunica histology:

1) it is Dense Regular Connetive Tisue (capitalized to show specific type) that is very much like a tendon. Pretty much exactly like a tendon, in fact.
2) it is usually composed of two sheaths (rarely 3, and very rarely only 1). One with fibers oriented circumferentially, the other with fibers oriented longitudinally.
3) the fibers are all parallel and when the tissue is at rest take on a crimped appearance.
4) when tension is created in these fibers the crimps straighten (the “toe” region of the stress-strain curve) and the fibers are pulled even closer together.
5) as point 4 happens, fluids, proteoglycans and other ground substance are squeezed from the extracellular matrix between the collagen fibers as they squeeze closer together. This action creates either creep (if a constant force is applied) or stress relaxation (if held at a constant state of strain/displacement). In reality, creep and stress relaxation happen due to the same mechanism: viscoelastic relaxation.

In irregular connective tissue types like dense irregular, or aereolar, I could see fiber alignment being really important as those tissues have a haphazard arrangement of fibers designed to resist pull from multiple directions, but in the dense connective tissue that makes up tendons, ligaments, and tunicae, the fibers are pretty much already aligned to resist force in one direction.

This realignment would happen a bit in the circumferential layer, but since linear tension is constant I am not sure why this would happen more with multiple attachment points.

What am I missing here? You can use sciency words if you need to, I understand most of them. :)

Roots

Oh Xeno, one more thing: that sentence should read “fiber re-alignment in the direction of the strain thereby achieving stress relief,” correct? I figured this is what you meant as it is basically the definition of how viscoelastic relaxation happens in tissues, but I just wanted to make sure we are on the same page and not talking about different things.

I do think that that is happening too, but I actually did mean it the way I wrote it; it describes, just like I wrote, the re-alignment of fibers, much like a Chinese finger toy, from orientations more normal to the stress vector to orientations more coincident with the stress vector, thereby achieving strain relief; rather than strain, they re-orient.

Please don’t lose track of the last thing I wrote though; But I could be wrong :) .

xeno