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[Luc Scholtès <question643660@xxxxxxxxxxxxxxxxxxxxx>]

Question #643660 on Yade changed:
https://answers.launchpad.net/yade/+question/643660

    Status: Open => Answered

Luc Scholtès proposed the following answer:
Hello,

We mentioned intR<1.5 for Rmax/Rmin=2 so the near neighbour interactions
keep conceptually "representative" of a rock microstructure even though,
I agree with you, it was not clearly explained. It is not easy to
explain but I'll try anyway:

Lets consider a line of 3 particles 1, 2, 3 such that R1=2, R2=1 and
R3=2. If you create bonds such as intR>1.5, then 1 and 3 will be bonded
together. A bond will thus be created "over" 2.

In granular materials such as granite or sandstone (where only
contacting grains interact one with each other), this is physically not
acceptable. Then, if your idea is to discuss the influence of the
microstructure of the medium on its overall behavior, this might be
problematic. I must precise that this sort of long range interactions
might nonetheless exist in some materials with exotic grain to grain
interactions (e.g. Van Der Waals forces).

Now, even though this can be conceptually not exactly representative of
the way grains interact in a geomaterial, it might nonetheless be an
acceptable way to overcome some difficulties faced by classic bonded
particle models to deal with certain types of cohesive materials (under
the condition that no direct link is done between the numerical
particles and the real grains). Another way to deal with such "non
physically acceptable" interactions would be to use an enhanced contact
law that would increased the degree of interlocking of grains (e.g. flat
joint contact model in PFC, or moment contact law in YADE).

Luc

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