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[Jan Stránský <question404012@xxxxxxxxxxxxxxxxxxxxx>]

Question #404012 on Yade changed:
https://answers.launchpad.net/yade/+question/404012

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hello Liu​,


[1] I want to output some results that can indicate the damage condition of
> the model. So which information should I be concerned, such as
> ‘cmpDamage’,  ‘cmpStress’ or ‘forceN’? What the specific meaning of
> cpmDamage and cmpStress are?


please be more specific what "damage condition" should be. Damage state and
its "amount"?

cpmDamage is not actual model damage, but ratio of actual tensile bond
strength to original tensile bond strength. If it is a sphere property, it
is average from all original bonds.

cpmStress is particle stress tensor [1]. The result should be (not tested
however) the same as utils.bodyStressTensors, differing by factor 0.62
(usual packing fraction with randomDensePack)


[2] I used the paraview to display the data set ‘spheres‘ and chosen
> cpmDamage following the 'Coloring' button. But the paraview appear error
> information such as ‘Warning: Range [1,10] invalid for log scaling.
> Changing to [0,0]. The cpmDamage information did not save, why?
> If I chosen cpmStress, it appears 'Warning: Range [0,9.31449e-05] invalid
> for log scaling.  Changing to [9.31449e-06,9.31449e-05].'. Can not paraview
> display the negative values?


I could not reproduce this. Data are saved ok and colored in paraview, too.
It looks like a problem in your paraview session, especially "log scaling"
message.. Paraview has no problem with negative values, logarithm of course
does :-)


[3] Can the paraview output the orientation distribution of sphere? If it
> can, How to do it?


Please be more specific on "orientation distribution of sphere" (I have no
idea what should it be..).


[4] Can you give me some post processing example of cpm material?


try yade/examples/concrete/uniax.py [2] with VTKRecorder, using [3], color
spheres by cpmDamage in range [0,1] and not using log scales in paraview.

cheers
Jan

[1] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.CpmState.stress
[2] https://github.com/yade/trunk/blob/master/examples/concrete/uniax.py
[3] https://yade-dem.org/doc/user.html#rendering-spherical-particles-glyphs

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