Yade

Yong Modulus rescale

Asked by Pawel

Hi everyone,
I tried to simulate a one dimension excitation of material built of spheres. I have a problem with young modulus rescale because I wanted to use spheres with a diameter bigger than the width of material. I tried to rescale Young module with this equation: E = Ef * w /(2 r) where E - is Young Module; Ef - is the young module from the experiment, w - width of material and r is the radius of spheres.

When I check the results of one dimension excitation the results from experiments (sigma/ epsilon) and from yade are not thesame (like there is some multiplication in Young Module)

I use in Engine:
  [Ig2_Sphere_Sphere_ScGeom6D(interactionDetectionFactor=1.3),
  Ig2_Wall_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom6D()],
  [Ip2_FrictMat_FrictMat_FrictPhys(),
  Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=False,setCohesionOnNewContacts=False),
  Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=True,setCohesionOnNewContacts=False),
  ],

Pawel

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Jérôme Duriez (jduriez) said : 		#1

Hi,

As a general remark, I think you are not supposed to mix Ip2_FrictMat_FrictMat_FrictPhys() and Ip2_CohFrictMat_CohFrictMat_CohFrictPhys() functors.
Because of class inheritance Ip2_CohFrictMat_CohFrictMat_CohFrictPhys() should be enough.

Mostly, having two Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(), differing only with setCohesionNow value, is meaningless and clearly not intended by the design of this class.

Did you have in mind something in particular mixing all these functors ?

Regarding now your issue with young material parameter, are you aware this may not be the particle Young's modulus ? (see the -- maybe elusive-- doc [*])

Actually in your case, young is not the particle Young's modulus because you do not seem to use Hertz Mindlin contact law. Thus, a curve fitting calibration step is mandatory before you can expect getting back experimental results.

(And I did not understand the rescaling concept :-) )

Jérôme

[*] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.FrictMat.young and https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Ip2_FrictMat_FrictMat_FrictPhys

Revision history for this message
Jérôme Duriez (jduriez) said : 		#2

As a remark which will not really help you with your problems, the "elusive" adjective referred to the doc at https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.FrictMat.young only.

Hopefully https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Ip2_FrictMat_FrictMat_FrictPhys is clear enough

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