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[Bruno Chareyre <question434659@xxxxxxxxxxxxxxxxxxxxx>]

Question #434659 on Yade changed:
https://answers.launchpad.net/yade/+question/434659

    Status: Open => Answered

Bruno Chareyre proposed the following answer:
>how does the periodic boundary apply load in yade

By changing the geometry of the periodic space. 
Arrange a long (infinite) chain of spheres along a line, with initially 10 spheres/meter and the same patern of spheres repeated every meter, then at the next step you decide that 1m becomes 0.9m, there is now 10spheres/0.9meter - they are squeezed and repulsive forces appear: you exerted a load. This would be 1D periodicity.

And then, how can we plot this on a screen? We don't want to display and
infinite number of spheres. So let's pick one randomly, call it
"origin", and display the movement (relative to origin) of the next 10
spheres on its right hand side. It will look like they all go to the
right in extension, and to the left in compression. That's really only a
graphical display issue, not a mechanical question.

By the way, if you compress something between two plates do you agree
that it is strictly the same (in statics) to 1/ move the bottom plate by
h and keep the top fixed, or 2/ move top by -h with fixed bottom, or 3/
move both by +/- h/2?

Did you see the documentation btw? (theoretical background chapter)

>and how does it choose the origin of coordinate?

A puzzling question actually!
The origin is placed at the point where the displacement is null.
Where is it that the displacement is null? You may ask.
Well... it is at the origin.
Or are you asking the distance between the sun and the origin of the periodic space? ;)

Bruno

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