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[Jan Stránský <question269063@xxxxxxxxxxxxxxxxxxxxx>]

Question #269063 on Yade changed:
https://answers.launchpad.net/yade/+question/269063

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hi Alexander,

thanks for more explanation. However, some parts are still not clear :-)

- concerning stress and strain, you can't plot just stress, you plot its
component or some other scalar representation? What do you plot in the
pictures? yy component?


if j == 0:
>            spheres[id].state.blockedDOFs='y' # Fixed all spheres
> connected to KGHO


- I don't believe the results are from MWE you posted, since the
displacement of spheres belonging to KGHO face is not constant (the blue
does not have constant shade), should be 0. Could you please rerun the
simulation and/or add coordinate system and scale to the pictures?
Moreover, are all KGHO points fixed only in y direction? If yes, then you
get perfect uniaxial loading and you you don't need any FEM for comparison,
just one line paper-pencil equation :-)

- anyway it will be difficult to calibrate Poisson's ratio to be 0.33 [2].
Just as the reminder, young and poisson parameters are not the values of
macroscopic Young's modulus an Poisson's ratio.

- you still did not reset the aabbEnlargeFactor
and interactionDetectionFactor [1]

- since the system is discrete, stress and strain values are just some
approximation. Moreover, at boundaries (=all spheres in your example :-),
the values might be approximated worse and also the physics itself
(distribution of interactions) is different than in "bulk" spheres.

- to save stresses (you can construct analogously the strains):

import __builtin__ # module visible from all python
stresses = bodyStressTensors()
__builtin__.my_stresses = stresses # make stresses visible from all python.
Be careful not to overwrite some important __builtin__ variable
vtk = export.VTKExporter('result')
vtk.exportSpheres(what=[...,('stress','__builtin__.my_stresses[b.id]')]) #
just stresses would not be visible from export module,
__builtin__.my_stresses are visible

cheers
Jan

[1] https://yade-dem.org/doc/user.html#creating-interactions
[2]
https://yade-dem.org/w/images/6/64/Stransky2010-Macroscopic-elastic-properties-of-particle-models.pdf


2015-07-10 21:21 GMT+02:00 Alexander
<question269063@xxxxxxxxxxxxxxxxxxxxx>:

> Question #269063 on Yade changed:
> https://answers.launchpad.net/yade/+question/269063
>
> Alexander posted a new comment:
> hm i need to do FEM example first to see what result is there, because
> now there is nothing to compare:) but anyway Jan  i'm waiting for your
> opinion and recommendations about all of this. Am i on the right way?
>
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