# Problem in consolidation

Asked by Xu Mengqian on 2020-02-24

Hi,all
I am trying to fix the orientation of clumps during the consolidation recently.But there are some problem in this procedure.
The periodic cell would be a rectangle after complete the consolidation, which is not a square.
This is my code. Thanks for your time.
########particle generation########
import random
sp = pack.SpherePack()
size = .38
sp.makeCloud(minCorner=(0,0,.05),maxCorner=(size,size,.05),rMean=.005,rRelFuzz=.4,num=1000,periodic=True,seed=1)
sp.toSimulation()
fout = file('packing_thirty.lst','w')
for b in O.bodies:
pos = b.state.pos
ori = 1. / 6. * pi
fout.close()

from math import *

mat_id = O.materials.append(FrictMat(young=8.e8,poisson=.8,frictionAngle=.0,density=10000))
mat = O.materials[mat_id]

fin = open('packing_thirty.lst','r')
fin.close()

z = 0.05
clump_id = []
coef = sqrt(3)/2+4./3*pi
print coef
area = 0.0
for i in xrange(len(clumpDataBase)):
x1 = float(clumpDataBase[i].split()[0])
y1 = float(clumpDataBase[i].split()[1])
x2 = float(clumpDataBase[i].split()[2])
y2 = float(clumpDataBase[i].split()[3])
mass = 2650 * (2*z) * (coef*radius**2)
cpos = [(x1+x2)/2.,(y1+y2)/2.,z]
color = numpy.random.rand(3)
clump_id.append(ID[0])
O.bodies[ID[0]].state.pos = cpos
O.bodies[ID[0]].state.mass = mass
O.bodies[ID[0]].state.inertia = [1.e10,1.e10,inertia]
O.bodies[ID[0]].state.blockedDOFs = 'zXYZ'
O.bodies[ID[0]-1].state.blockedDOFs = 'zXYZ'
O.bodies[ID[0]-2].state.blockedDOFs = 'zXYZ'

print area
mn,mx = utils.aabbExtrema()
print mn,mx
O.periodic = True
O.cell.setBox(0.38,0.38,z*2)
print len(clump_id)

O.dt = 3.e-5
print O.dt

def shear():
print O.cell.hSize
O.pause()

O.engines = [
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb()]),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_ScGeom_FrictPhys_CundallStrack()]
),
PeriTriaxController(
dynCell=True,
goal=(-1.e5,-1.e5,0),
relStressTol=.001,
maxUnbalanced=.001,
maxStrainRate=(.25,.25,0.),
doneHook='shear()',
label='biax'
),
NewtonIntegrator(damping=0.2)
]
O.run()

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2020-02-24
2020-02-27
 Bruno Chareyre (bruno-chareyre) said on 2020-02-24: #1

Hi Xu,
Please elaborate a question. It is clear that a rectangle is not always a square, but... what is that all about?
Bruno

 Xu Mengqian (yrainy.) said on 2020-02-24: #2

Hi Bruno，
What you means is that the cell is not always a square after consolidation? But this is isotropic consolidation, why it would be a rectangle? When I didn’t control the orientation of clumps,the cell is a square after isotropic consolidation.
Xu

 Chareyre (bruno-chareyre-9) said on 2020-02-24: #3

«isotropic» was not mentioned in the question, while the consolidation
script shiped in yade examples is uniaxial... it was hard to guess!
Bruno

Le lun. 24 févr. 2020 19:47, Xu Mengqian <
<email address hidden>> a écrit :

> Question #688968 on Yade changed:
>
> Hi Bruno，
> What you means is that the cell is not always a square after
> consolidation? But this is isotropic consolidation, why it would be a
> rectangle? When I didn’t control the orientation of clumps,the cell is a
> square after isotropic consolidation.
> Xu
>
> --
>
> _______________________________________________
> Post to : <email address hidden>
>

 Jan Stránský (honzik) said on 2020-02-24: #4

> But this is isotropic consolidation, why it would be a rectangle?

"how much" rectangle it is?
Your stress should be isotropic (can you check if it si true during the simulation?).
Which does not necessarily imply isotropic strain, if your packing (or its overall mechanical response) is not isotropic..

cheers
Jan

 Xu Mengqian (yrainy.) said on 2020-02-25: #5

Hi bruno，
The consolidation script is biaxial isotropic consolidation. I was trying the 2D simulation.

 Xu Mengqian (yrainy.) said on 2020-02-25: #6

Hi Jan,
I don’t know how to tell if it’s isotropic, but my stress is isotropic.
So it is strange that the cell becomes a rectangle after consolidation.

cheers
Xu

 Jan Stránský (honzik) said on 2020-02-25: #7

Hello,

instant replay:
> "how much" rectangle it is?
1:2? 1:1.01?

> So it is strange that the cell becomes a rectangle after consolidation.

there is no strong reason not to be rectangular. The only case it remains square is the case that the packing is isotropic. It seems not to be the case with your clumps.

cheers
Jan

 Xu Mengqian (yrainy.) said on 2020-02-27: #8

Hello,

> "how much" rectangle it is?

>It seems not to be the case with your clumps.
If I control the orientation of clump, the packing is not isotropic? But I tried the SudoDEM (base on the YADE). the packing is isotropic and the cell remains square.

 Chareyre (bruno-chareyre-9) said on 2020-02-27: #9

I guess you have to report in more details and to provide test scripts for
both softwares if you want to discuss a difference in results.
Else it is meaningless.

Ultimately, though, the question is to be asked to sudoDEM. It should give

Bruno

Le jeu. 27 févr. 2020 07:14, Xu Mengqian <
<email address hidden>> a écrit :

> Question #688968 on Yade changed:
>
> Xu Mengqian posted a new comment:
> Hello,
>
> > "how much" rectangle it is?
> The rectangle is about 1:1.1.
>
> >It seems not to be the case with your clumps.
> If I control the orientation of clump, the packing is not isotropic? But I
> tried the SudoDEM (base on the YADE). the packing is isotropic and the cell
> remains square.
>
> --
>
> _______________________________________________
> Post to : <email address hidden>
>
>
>

 Jan Stránský (honzik) said on 2020-02-27: #10

> If I control the orientation of clump, the packing is not isotropic?

yes, of course. I would be surprised if such "aligned fibres" would give isotropic response.

> But I tried the SudoDEM (base on the YADE). the packing is isotropic and the cell remains square.

There might be several reasons. Is it e.g. possible that in SudoDEM there is prescribed strain instead of stress? What are the final stresses?

cheers
Jan