The biggest problem I have with your posts is that while they describe something in nature, I've never seen you relate these things in any practical way to the level of human interaction.
You do describe how shear forces affect a structure but you have never (that I've seen) described 1) how you are able to make yourself immune to these forces or 2) how you are able exploit them in another person.
Those are the only two vital topics in this discussion and without addressing those, we might as well attribute everything to "karma" or "the weather" or "the way things are."
The idea that most people in these discussions are working on is how to eliminate these potential shears throughout our own structure and how to direct our energies to collapse or repel the attacker's structure.
I know that, and my conclusion as to what is mechanically going on leads to the secondary conclusion that you are doing
things in ways that make sense but according to explanations or descriptions that cut against your declared training goals. As to your numbered points:
1) You CANNOT eliminate them, any more than you can eliminate waves in the ocean. They are too great a part of what makes a bipedal creature work and work efficiently. You can find the dynamic balance where the neutral line lies, like the bicycle or the surfboard -- but it is never trivially stable. You must USE them both explicitly in others and internally in yourself --and they are not different in uses or perception in either case. If I understand how my own leg truly moves when I walk with minimal conscious "intent" I can make my opponent's leg move also -- and by the same means. The body moves in this way according to the principles illustrated in the kokyu undo, most particularly, happo (or zengo) undo, funatori undo, ude furi, and tekubi furi.
2) Your second point is a question that betrays our fundamental crosstalk. You are looking for a set of defined problem events with determined solutions; I am looking at a set of problems that have a common operation in their solutions -- all of which are to me indeterminate in result before executing it. Diffy-q to your linear quadratics -- Takemusu
-- pick a label. I can tell you what shape the solution will take -- in fact I have -- but not its actual path or the number of iterations of the operative process that will arrive at that solution.
All the wave-line diagrams are useless unless you can show what you do with your body (which bones, which muscles, etc.) to eliminate shear in yourself and be able to apply force that exploits the shear potential in the other guy.
Without that, it's all abstract intellectualism and has no interest for people who are actually trying to use the principles.
Your third criticism is simply misplaced given what I am actually doing. I am not using abstractions but concretes -- accurate diagrams of perceptible physical conditions, and mechanically admissible physical examples of common experience. These are used to illustrate concrete shapes of dynamics --which can be perceived. I keep a length of chain in the dojo to demonstrate some of them -- does that sound like "intellectualism"?
I show students how, when a throw is begun in kuzushi -- the static balance sphere is plainly overcome but that while flat on the feet is more statically stable, using
the applied shear of the throw itself to throw the heels forward first results in a far greater dynamic range
of the balance sphere, and even kaeshiwaza if applied properly. It only works because I use the shear applied to the body to shear other parts of my body to absorb some of the shear and be able to convert the rest to advantage without conscious (and slow) intermediation. Physics is faster than neurology. Does that sound "impractical" to you ?
The diagrammed principles show how that action in the body works in slightly simplified form (and allow a mental image of its action or "intent" if you will) that can can be more readily and more correctly modelled in practice. Moreover, I strive always to relate them to the traditional modes of description -- which are not usually wrong at all, just terribly ad hoc in their approach to modelling. My third Dan MJER companion compare notes on the prescritpive forms of their sword bunkai, and my arriving at explanations ( with extendable conclusions) as to why the traditional form is illustrated in that way. It vitalizes their practice and keeps the forms from becoming dead repetition, as there are recognizable reasons for what is prescribed once this set of observations is applied.
I use what I speak of. Tolerably well, I am told. I am not seeking to win converts or disciples -- I just want to get closer to truth in all respects. This is truth as far as it goes, and I'll be the first to say I have farther to take it yet.