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[Leonard <question701941@xxxxxxxxxxxxxxxxxxxxx>]

New question #701941 on Yade:
https://answers.launchpad.net/yade/+question/701941

Hi,
I am using TriaxialStressController for a triaxial compression simulation and I'd like to ask that how to restart recording triax data from an insteresting state.

Let's say, I have a packing and I use TriaxialStressController to compress it from state 0 to state 1, during this process the triax.strain evolves from Vector3(0,0,0) to Vector3(e11,e22,e33) and e11,e22,e33 are non-zero values. Now I want to restart recording the simulation data from state1, and I'd like to set the triax.strain at state 1 to Vector3(0,0,0).

Is it possible?

Thanks
Leonard

A MWE for illustrating compression process from state 0 to state 1 is as below:

from yade import pack

nRead=readParamsFromTable(
 num_spheres=1000,# number of spheres
 compFricDegree = 30, # contact friction during the confining phase
 key='_triax_base_', # put you simulation's name here
 unknownOk=True
)
from yade.params import table

num_spheres=table.num_spheres# number of spheres
key=table.key
targetPorosity = 0.43 #the porosity we want for the packing
compFricDegree = table.compFricDegree # initial contact friction during the confining phase (will be decreased during the REFD compaction process)
finalFricDegree = 30 # contact friction during the deviatoric loading
rate=-1e-1 # loading rate (strain rate)
damp=0.2 # damping coefficient
stabilityThreshold=0.01 # we test unbalancedForce against this value in different loops (see below)
young=5e6 # contact stiffness
mn,mx=Vector3(0,0,0),Vector3(1,1,1) # corners of the initial packing

O.materials.append(FrictMat(young=young,poisson=0.5,frictionAngle=radians(compFricDegree),density=2600,label='spheres'))
O.materials.append(FrictMat(young=young,poisson=0.5,frictionAngle=0,density=0,label='walls'))

walls=aabbWalls([mn,mx],thickness=0,material='walls')
wallIds=O.bodies.append(walls)

sp=pack.SpherePack()

sp.makeCloud(mn,mx,-1,0.3333,num_spheres,False, 0.95,seed=1) #"seed" make the "random" generation always the same
O.bodies.append([sphere(center,rad,material='spheres') for center,rad in sp])

triax=TriaxialStressController(
 maxMultiplier=1.+2e4/young, # spheres growing factor (fast growth)
 finalMaxMultiplier=1.+2e3/young, # spheres growing factor (slow growth)
 thickness = 0,

 stressMask = 7,
 internalCompaction=True, # If true the confining pressure is generated by growing particles
)

newton=NewtonIntegrator(damping=damp)

O.engines=[
 ForceResetter(),
 InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]),
 InteractionLoop(
  [Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
  [Ip2_FrictMat_FrictMat_FrictPhys()],
  [Law2_ScGeom_FrictPhys_CundallStrack()]
 ),
 GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),
 triax,
 TriaxialStateRecorder(iterPeriod=100,file='WallStresses'+table.key),
 newton,
]

Gl1_Sphere.stripes=0
if nRead==0: yade.qt.Controller(), yade.qt.View()

triax.goal1=triax.goal2=triax.goal3=-100000

while 1:
  O.run(1000, True)
  unb=unbalancedForce()
  print 'unbalanced force:',unb,' mean stress: ',triax.meanStress
  if unb<stabilityThreshold and abs(-100000-triax.meanStress)/100000<0.001:
    break

print "### Isotropic state reached ###"

import sys #this is only for the flush() below
while triax.porosity>targetPorosity:
 # we decrease friction value and apply it to all the bodies and contacts
 compFricDegree = 0.95*compFricDegree
 setContactFriction(radians(compFricDegree))
 print "\r Friction: ",compFricDegree," porosity:",triax.porosity,
 sys.stdout.flush()
 O.run(500,1)

print "### Compacted state reached ###"

triax.internalCompaction=False

setContactFriction(radians(finalFricDegree))

triax.stressMask = 5
triax.goal2=rate
triax.goal1=-100000
triax.goal3=-100000
newton.damping=0.1

print "click run to start deviatoric loading"
from yade import plot

def history():
 plot.addData(e11=-triax.strain[0], e22=-triax.strain[1], e33=-triax.strain[2],
   ev=-triax.strain[0]-triax.strain[1]-triax.strain[2],
   s11=-triax.stress(triax.wall_right_id)[0],
   s22=-triax.stress(triax.wall_top_id)[1],
   s33=-triax.stress(triax.wall_front_id)[2],
   i=O.iter)

def stop():
 if -triax.strain[1]>0.05:
  O.pause()
  print "state1 is reached"
  print "triax.strain is ",triax.strain

O.engines=O.engines+[PyRunner(iterPeriod=20,command='history()',label='recorder')]
O.engines=O.engines+[PyRunner(iterPeriod=1,command='stop()',label='stop')]
##### Finish


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