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[Robert Caulk <question630468@xxxxxxxxxxxxxxxxxxxxx>]

Question #630468 on Yade changed:
https://answers.launchpad.net/yade/+question/630468

    Status: Open => Answered

Robert Caulk proposed the following answer:
Hello Manon,

>And that is where I get lost. I do not understand the dimension of this
Aeq over li quantity. I think that in >the way it is expressed here, it
actually has no dimension, where it should have a m dimension ?

You've found a typo in the DEM background/Václav's thesis. It should
read "A_eq = pi * min(r1, r2)^2" since that is in fact what is used in
the concrete model [1]. The unit of stiffness is force/displacement or
in SI, N/m. So in this case, the units work out since E Pa * A_eq m^2/
l_i m  -> Pa*m = N/m.

I am curious though why he chose to use min(r1, r2). This seems like it
would skew the interaction stiffness distribution left resulting in a
less stiff specimen. At the end of the day, we always calibrate the
micro-properties to experimentally observed macro behavior. In this
case, we'd just have to compensate for that skewed distribution with a
different combination of micro-parameters. Idk maybe someone can shed
light on that.

[1]https://github.com/yade/trunk/blob/dafe23a8e34ab581edc0425d28290fc5ba591ce8/pkg/dem/ConcretePM.cpp#L315

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