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Old 01-04-2011, 08:27 AM   #46
Erick Mead
 
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Dojo: Big Green Drum (W. Florida Aikikai)
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Re: Direction of Groundpath

Quote:
Walter Martindale wrote: View Post
People are mostly water, and as mentioned above, not a non-Newtonian fluid. We're a bunch of plasma, cells, and tissues (made up of cells) the water is a (largely) saline solution.
Ground matter in tissue is far more than just saline, but I am not sure how far that issue really goes -- there are simpler structural aspects that carry most of problem.

Quote:
Walter Martindale wrote: View Post
I have a question about the corn starch pseudo solid... What happens when it's hit by, say, a 200 grain piece of lead travelling at 780 fps? If you hit a human with that, a hole and wound channel form and a bunch of plasma, platelets, red cells and other stuff leaks out.
A good question, but since ballistic gelatin stops a ~7.62 mm battle rifle round inside of 24 inches, I suspect similar performance -- and the fact of a temporary but relatively large wound cavity indicates shear resistance by the tissue as high shear is what causes most cavitation in fluids.

Quote:
Walter Martindale wrote: View Post
I think this spirals stuff is primarily an interpretation of the concept that you keep the work in your "centre" and not off to the sides, and you try to make the motions relatively circular. However, there's a lot of bilge that gets blabbed in the guise of science - but that doesn't make it science...
What stops people from doing in-depth biomechanics research into what actually happens in aikido techniques is - money... A biomechanics lab with a force-platform big enough to do any meaningful measurement, synched to a system of cameras capable of being frame-synched and having high shutter speeds, working with two people, computing the information in 3 dimensions is rather an immense task, takes money to fund the research, and, frankly, because it don't win the world series, super bowl, or the F1 constructors title, ain't gonna have the money spent on it. Well, not any time soon..
W
Been done in terms of taichi and fajin striking -- and talked about here already, actually. I certainly acknowledge the relation to our principles in that art.

http://ucbprogram.com/node/24

http://www.youtube.com/watch?v=HN88QIsMHqA

Some take away quotes: (1st hypothesis deals with ground path) "[he] applies to the ground a force of 2,200 newtons and a torque of 11,000 newton-meters" the caption noting that this is a force 3 times body weight --but a torque 16 times body weight x meters" -- and allowing that these measure are available to apply to the target.

I will leave it to you to determine the predominating element magnifying that impact.

(2d Hypothesis deals with the sequential rotations of his lower body, hips, shoulders and arms): "Master Chen optimizes momentum transfer into the target by translating the angular momentum of his hips and shoulders into the linear momentum of his striking hand." The graph at 1:50 shows that the sequence of peak angular velocity (starting with his left foot step) goes left foot - pelvis - right foot - shoulders - hand. The peak floor reaction at the delivery of the strike by the hand.

This is a progressive torque shear wave. If it were whole-body extension at once by some other mechanism there would be no definable peaks of action at different times .

That leads to their 3d hypothesis which deals with the concentration of momentum into the impulse at the moment of strike.

This is mechanically the same as a folded chain falling with one end held by a hook. It comes into maximum tension as it reaches the limits of its fall from its point of suspension. The end of the chain accelerates downward FASTER than gravity because of the conservation of angular momentum in each successively shorter ( (thus lighter) length of moving links as it falls requires each shorter length to move faster -- just like a whip.

The same mechanism is in evidence with the fajin strike, using his body weight and the earth as his compressive anchor to deliver a strike in extreme accelerating tension. Only torsional shear combines those forces in a multiplicative way.

Mike's consideration of ground path is correct on both of our proposed mechanisms -- but its role in a shear-dominated action is different from that of a reactive linear force action, and the data above strongly suggest the torque shears dominate the mechanism of transfer.

FWIW.

"The spirit of bees" in furitama and tekubifuri is a different application of the same principle seen in fajin -- to actuate reflexive elements in the body that are highly sensitive to the destructive power of torque shears as a protective mechanism -- thus catastrophically buckling the structural capacity of balance by a combination of purely mechanical peak shear actions and bio-mechanical reflex reactions by the target.

The slower more undulating mechanisms, the "demon snake" (seen in funatori, ude furi, zengo undo etc.) do this slowly with a more constant level cyclic shear that results in a "softening of the joints" to better effectuate the transfer of shears through the body. This eventually allows one to actually sense the dislocations of those shears in the connected opponent, through the same kinesthetic mechanisms in our own bodies (golgi tendon organs and gamma motor neurons) that trigger the reflexes that the higher frequency actions exploit in the target body.

Cordially,

Erick Mead
一隻狗可久里馬房但他也不是馬的.
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