yade-users team mailing list archive

[Anton Gladky <gladky.anton@xxxxxxxxx>]

Ok, thank you, will try to "struggle to it"

http://yade.wikia.com/wiki/FAQ#I_have_a_problem_with_.22peak_results.22._What_is_wrong.3F


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Anton Gladkyy


2009/8/7 Václav Šmilauer <eudoxos@xxxxxxxx>

>
> > Has anybody the problem with "peak results"?
> > I mean, when you record the data from anything, for example force
> > affecting on facet or sphere,
> > sometimes you get "pick results" which are twice or more larger than
> > normal result.
> > It happens just for a short period, like a noise.
>
> Eh, probably everybody has had that problem.
>
> Taking force on 1 particle makes no sense, you have to average it
> somehow. DEM doesn't solve for equilibrium, therefore you can either let
> the simulation stabilize somehow (dissipate all the kinetic energy), or
> average somehow what you see over larger area (or both). You can compute
> forces on a specimen cross-section or some meaningfully defined set of
> particles; if you have a facet that touches many spheres, that could be
> a good candidate as well, as long as the sphere move independently.
>
> You can try taking force from 1 single particle and smooth it using
> moving average or similar techniques (they are available in the numpy
> package), but that is just "graph aesthetics".
>
> e.g. examples/concrete/uniaxial sums forces (in UniaxialStrainer) on all
> particles that are considered supports and lower and higher supports are
> then averaged. There are still some osciallations (as there are waves
> going back and forth in the specimen), but that is not so marked unless
> you go to very high loading rates. The same example also plots
> cross-section forces (i.e. forces in interactions that cross that plane)
> and you can see that they differ.
>
> Vaclav
>
>
>
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