yade-users team mailing list archive

[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,


> thank's for fixing __builtin__.my_stresses. Now i'm wondering how to
> import strains because of  TW.deformation(b.id,i,j) works only for one
> sphere, i think i need to create new array strains[] and put all values
> in it first and then use __builtin__, or it can be done more elegantly?
>
>
I don't know TessalationWrapper, but constructing the values can be done
relatively elegantly:

strains = [Matrix3(*[TW.deformation(b.id),i,j) for i in xrange(3) for j in
xrange(3)]) for b in O.bodies]


>
> 2) Well, let's consider the first component of displacement which i get
> with Yade -
> (http://i11.pixs.ru/storage/5/5/3/pic1JPG_1997634_18020553.jpg) and
> Ansys - (http://i11.pixs.ru/storage/5/5/7/pic3JPG_1380016_18020557.jpg)
>
> As u can see they are different,  Yade has values' range
> [-0.1038,0.1038] Ansys range is [-0,0018636,0,0018636]
>
> 3) The same thing with the x component of normal stress (first component
> of stress tensor)
> Yade - (http://i11.pixs.ru/storage/5/5/9/pic2JPG_1013994_18020559.jpg)
> Ansys - (http://i11.pixs.ru/storage/5/6/4/pic4JPG_1715017_18020564.jpg)
> Yade range = [-3.32165e7,6.07687e7] Ansys range = [-2,2244e7,9,8264e7].
>
> The size of model in Ansys is the same (16,16,2) -
> (http://i11.pixs.ru/storage/5/8/8/pic6JPG_8207000_18020588.jpg) also u
> can see computational mesh
> (http://i10.pixs.ru/storage/5/9/1/pic7JPG_2524627_18020591.jpg)
>
> So, any ideas?
>

The difference is most likely because 'young' and 'poisson' arguments of
CpmMat are interaction parameters, *not* the macroscopic paremters (e.g.
different material in FEM and DEM). A standard way is to calibrate these
micro parameters to get macroscopically what you want. In one of my
previous messages you can find a reference on this.

The perfect uniaxial condition (recall the paper-pencil example I suggested
:-) may be a good starting point. Then you would have constant stress and
stress, linear displacement, Young's modulus and Poisson's ratio,
everything computable by hand. Also for the first FEM and DEM comparison, I
would use uniaxial tension (most simple loading scenario) instead of that
you are using now..

Concerning the plotting, I messed a bit the axes, what I meant was to print
both displacement and stresses in the direction of applied force. Anyway,
if you want the same results, you have to play with input material
parameters :-)

cheers
Jan

-- 
You received this question notification because you are a member of
yade-users, which is an answer contact for Yade.