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[ehsan benabbas <question688134@xxxxxxxxxxxxxxxxxxxxx>]

New question #688134 on Yade:
https://answers.launchpad.net/yade/+question/688134

Hi everyone,

I am using Ubuntu 18.04, and Yade 2019-08-08.git-775ae74

I use the Triaxial code by Bruno Chareyre [1] to run triaxial simulation on my specimen.

[1] https://gitlab.com/yade-dev/trunk/blob/master/examples/triax-tutorial/script-session1.py

Unfortunately, the result is not rational and thus my questions are:

1- Why the "q" (deviatoric stress) is positive? (at the end of the deviatoric part)
2- Why axial deformation (axial strain, volumetric strain) is zero?  (at the end of both the confining and deviatoric parts)
3- Why sigma2 is less than SigmaIso in the code? (at the end of the deviatoric part)
4- How can I save the packing (particles' coordinates as X,Y, Z and their radius as R) in a text file after make the packing?

%%%%%%%%%%%%%%%%%%%%%%%%

I only made the following changes in [1]:

num_spheres=20000,
targetPorosity = 0.4
young=200000000
poisson=1
mn,mx=Vector3(0,0,0),Vector3(0.02,0.02,0.02)
sigmaIso=-500000
particleDensity=2000
O.materials.append(FrictMat(young=young,poisson=poisson,frictionAngle=radians(compFricDegree),density=particleDensity,label='spheres'))
from yade import pack
sp=pack.SpherePack()
clumps=False
volume = (mx[0]-mn[0])*(mx[1]-mn[1])*(mx[2]-mn[2])
sp.makeCloud(mn,mx,0.0002,0.5,num_spheres,False, 0.95,seed=1)
O.bodies.append([sphere(center,rad,material='spheres') for center,rad in sp])
triax.goal1 = sigmaIso
triax.goal2 = sigmaIso
triax.goal3 = sigmaIso
f unb<stabilityThreshold and abs(sigmaIso-triax.meanStress)/sigmaIso<0.001:
triax.goal1 = sigmaIso
triax.goal2 = rate
triax.goal3 = sigmaIso

%%%%%%%%%%%%%%%%%%%%%%%%

And the output is:

ehsan@ehsan:~/Desktop$ /home/ehsan/yade/install/bin/yade-2019-08-08.git-775ae74  Q.py
Welcome to Yade 2019-08-08.git-775ae74 
Using python version: 3.6.9 (default, Nov  7 2019, 10:44:02) 
[GCC 8.3.0]
TCP python prompt on localhost:9000, auth cookie `cyueka'
XMLRPC info provider on http://localhost:21000
Running script Q.py
************** START **************
============ DEFINING VARIABLES ============
============ DEFINING FUNCTIONS ============
============ DEFINING MATERIALS ============
============ DEFINING PACKING ============
============ DEFINING TRIAXIAL TEST ============
============ DEFINING ENGINES ============
The constructor with a shareWidget is deprecated, use the regular contructor instead.
Number of elements:  20006
Box Volume:  3.714574414115203e-81
Box Volume calculated:  8.000000000000001e-06
============ APPLYING CONFINING PRESSURE ============
~~~~~~~~~~~~~ Phase_01: Converging to Isotropic Compression, 50kPa ~~~~~~~~~~~~~
unbalanced force: nan  mean stress engine:  0.0  mean stress (Calculated):  -0.0
porosity= 0.8920863623534938
void ratio= 8.266669364586804
.
.
.
~~~~~~~~~~~~~ Phase_01: Converging to Isotropic Compression, 50kPa ~~~~~~~~~~~~~
unbalanced force: 5e-05  mean stress engine:  0.0  mean stress (Calculated):  -0.0
porosity= 0.874623180910073
void ratio= 6.975956059969474
Axial Strain 0.0
################## Isotropic phase is finished and saved successfully ##################
============ REACHING TARGET POROSITY ============
 Friction:  28.5  porosity: 0.874623180910073
 Friction:  27.075  porosity: 0.8708050821138507
.
.
.
Friction:  2.0832852056170093  porosity: 0.42156339492430284
Friction:  1.9791209453361587  porosity: 0.40486546436292276
Final Number of elements:  20006
Final Box Volume:  8.000000000000001e-06
Final Box Volume calculated:  8.000000000000001e-06
Final porosity= 0.38946593512762423
Final void ratio= 0.6379102453669592
################## Target porosity is reached and compacted state saved successfully ##################
============ APPLYING DEVIATORIC LOADING ============
step= 59000 unbalanced force: 0.22470167357987816  sigma2:  -121121.56365292308 q= 378878.4363470769
Axial Deformation (%) 0.0
~~~~~~~~~~~~~ Phase_02: Converging to Deviatoric Compression, Strain Rate ~~~~~~~~~~~~~
################## Deviatoric phase is finished and saved successfully ##################
============ RECORD AND PLOT DATA ============
/home/ehsan/yade/install/lib/x86_64-linux-gnu/yade-2019-08-08.git-775ae74/py/yade/plot.py:444: MatplotlibDeprecationWarning: 
The 'verts' kwarg was deprecated in Matplotlib 3.0 and will be removed in 3.2. Use 'marker' instead.
  scatter=pylab.scatter(scatterPt[0] if not math.isnan(scatterPt[0]) else 0,scatterPt[1] if not math.isnan(scatterPt[1]) else 0,s=scatterSize,color=line.get_color(),**scatterMarkerKw)
************** END **************
Analysis has been taken for 661.858 seconds or 11.030966666666666 minutes
[[ ^L clears screen, ^U kills line. F12 controller, F11 3D view (press "h" in 3D view for help), F10 both, F9 generator, F8 plot. ]]

In [1]:

%%%%%%%%%%%%%%%%%%%%%%%%

I will copy the whole code in the first comment.

Thank you for your help.
Ehsan

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