anticlastic bending

[Grimer]

Has anyone any experimental experience of this phenomena?

[rasselas]

From wiki-tionary:
Anticlastic = "(of a surface) curved in opposite ways in two directions; saddle-shaped"

wikipedia has no articles referring to this phenomena (that I could find). Thus, please fill us in a little more Grimer.

PS - I'm assuming that's then like a concave lens? - - > )( vs () ?

[Grimer]

Nope. The wiki-tionary is a very accessible description since along the horse's spine the saddle is curved upwards and perpendicular to the spine it is curved downwards.

Thanks for turning that up.

My experience of anticlastic bending is in the deflection of beams where it is not at all obvious and usually ignored.

[ovyyus]

http://www.ted.com/talks/sheila_patek_c ... imals.html

[rasselas]

Grimer, so you're saying (in translated form) that it IS like a concave lens - - > )(
BUT that the latter parentheses is rotated in the third dimension 90*... sorta like a four leaf clover... with two opposed leaves pushed down; while perpendicular to them, the other two (opposing) leaves are pulled upward?

Ok, next question... a saddle is anticlastic without being bended... that is in it's resting or static state it is shaped that way. So when you say "anticlastic bending"... you mean that a normal straight beam under application of force on two (the far opposite) ends of the beam? (or do you mean with four forces being applied?)

Amazon has one book for sell (literally one seller) at: http://www.amazon.com/Study-Anticlastic ... B000LVBS7M

I read somewhere, "One can easily demonstrate (the rare effect of) anticlastic bending by buckling a rectangular prismatic eraser between their fingers". I have no idea what a prismatic eraser is though... maybe it's that thing that keeps making all my glass prisms disappear?

BTW, -clastic = dividing up into parts... so etymologically anti-clastic means not dividing up into parts. sorta contradictory sounding to me.

Lastly... I've never experienced that in my experiments... and find it very hard to induce even paper to deform that way when only applying two forces... but applying four forces (in two sets of oppositional direction) (to a rectangle or such)... then I think most of us would of experienced that... though probably never given it much attention. Just a guess, as I don't see much to it yet.

[Grimer]

http://www.ted.com/talks/sheila_patek_c ... imals.html

A hyperbolic paraboloid is the right shape but not necessarily under stress. Anticlastic bending is most obvious in short thick wide beams simply supported at the ends.

[path_finder]

Dear Grimer,
An ancient (3500 BC) item with three anticlastic bendings: the 'flowerbowl'.
This particular geometry allows two simultaneous orthogonal motions, like I explained before here:
http://www.besslerwheel.com/forum/download.php?id=8811
Remember that two orthogonal motions are really useful for the implementation of a reciprocator.
In the 'flowerbowl' this feature is tripled, every 120 grades (IMHO a much more efficient geometry than this of order 'four' like it seems to be for the Bessler's wheels).