yade-dev team mailing list archive

[Luc Scholtès <lscholtes63@xxxxxxxxx>]

Hi guys,

As illustrated in attached figures, I always get the same curve when
running the simulation with the same packing (with either
neverErase=True or neverErase=False). I don't face the problem you
mentioned Robert...

I do have different curves for neverErase=True and neverErase=False
though (initial point of the bug report). The difference is "minimal" in
this case (post peak) but I have other results where it is pretty
important (even pre peak).

Just to explain a bit further:

I try to compute the change of permeability due to stress induced
damage. To do so, I run a compression and compute the permeability of
the sample at different stages of the loading (the simulation is not
coupled, I just call for DFNFlow to compute the permeability). I thus
need to keep track of the induced cracks (hence the neverErase=True) so
as to take into account the evolution of their aperture during the
loading.

Luc


** Attachment added: "figsLuc.zip"
   https://bugs.launchpad.net/yade/+bug/1790167/+attachment/5183936/+files/figsLuc.zip

-- 
You received this bug notification because you are a member of Yade
developers, which is subscribed to Yade.
https://bugs.launchpad.net/bugs/1790167

Title:
  JCFPM: "neverErase" modifies the simulated behavior while it should
  not

Status in Yade:
  New

Bug description:
  I noticed that running the exact same simulation (with same initial
  packing) gives different behaviors (stress-strain response in, e.g., a
  compression test) when neverErase is True or False. Given the purpose
  of neverErase (keep record of broken contacts, primarily for DFNFlow),
  it should not. The difference can be more or less important depending
  on the situation but it always exists. I could not figure out the
  cause of this yet but it seems that it comes from the treatment of
  broken contacts (obviously).

  Here is a simulation (uniaxial compression) that illustrates the
  problem. Running the same script using the exact same sample (to make
  sure the error does not come from a difference in the packings used)
  with either neverErase=True or neverErase=False produces 2 stress-
  strain curves which deviate at some point during the simulation. I
  made sure that the error is only due to neverErase by running the same
  simulations several times. The curves obtained with neverErase=True
  are always identical, as the curves obtained with neverErase=False.
  For those who would be interested, I also attach a packing  and the
  python script to plot the curves (below the simulation script).

  
  ### yade script ###

  
  from yade import ymport, pack, plot                                 

  #### material definition
  def sphereMat(): return JCFpmMat(type=1,density=3000,young=1e9,poisson=0.2,tensileStrength=1e6,cohesion=10e6,frictionAngle=radians(30))

  ##### create the specimen
  #L=0.10
  #D=0.05
  #pred=pack.inCylinder((0,0,0),(0,0,L),D/2.)
  #O.bodies.append(pack.regularHexa(pred,radius=D/20.,gap=0.,material=sphereMat)) 
  #O.bodies.append(pack.randomDensePack(pred,radius=D/20.,rRelFuzz=0.4,spheresInCell=1000,memoizeDb='/tmp/gts-triax-packings.sqlite',returnSpherePack=False,color=(0.9,0.8,0.6),material=sphereMat))

  #### import the specimen
  O.bodies.append(ymport.text('121_3k.spheres',scale=1.,shift=Vector3(0,0,0),material=sphereMat))

  #### help define boundary conditions (see utils.uniaxialTestFeatures)
  bb=utils.uniaxialTestFeatures()
  negIds,posIds,longerAxis,crossSectionArea=bb['negIds'],bb['posIds'],bb['axis'],bb['area']

  ################# DEM loop + ENGINES DEFINED HERE

  O.engines=[
   ForceResetter(),
          InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=1.2,label='Saabb')]),
   InteractionLoop(
    [Ig2_Sphere_Sphere_ScGeom(interactionDetectionFactor=1.2,label='SSgeom')],
    [Ip2_JCFpmMat_JCFpmMat_JCFpmPhys(cohesiveTresholdIteration=1,label='interactionPhys')],
    [Law2_ScGeom_JCFpmPhys_JointedCohesiveFrictionalPM(neverErase=False,label='interactionLaw')]
   ),
   UniaxialStrainer(strainRate=-0.01,axis=longerAxis,asymmetry=0,posIds=posIds,negIds=negIds,crossSectionArea=crossSectionArea,blockDisplacements=1,blockRotations=1,setSpeeds=0,stopStrain=0.1,dead=1,label='strainer'),
   GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=10,timestepSafetyCoefficient=0.8,defaultDt=utils.PWaveTimeStep()),
   NewtonIntegrator(damping=0.4,label='newton'),
   PyRunner(iterPeriod=int(100),initRun=True,command='recorder()',label='data'),
  ]

  ################# RECORDER DEFINED HERE

  def recorder():
      yade.plot.addData({'i':O.iter,
                         'eps':strainer.strain,
                         'sigma':strainer.avgStress,
                         'tc':interactionLaw.nbTensCracks,
                         'sc':interactionLaw.nbShearCracks,
                         'te':interactionLaw.totalTensCracksE,
                         'se':interactionLaw.totalShearCracksE,
                         'unbF':utils.unbalancedForce()})
      plot.saveDataTxt('compressionTest_1')

  ################# PREPROCESSING

  #### manage interaction detection factor during the first timestep and then set default interaction range
  O.step();
  ### initializes the interaction detection factor
  SSgeom.interactionDetectionFactor=-1.
  Saabb.aabbEnlargeFactor=-1.

  ################# SIMULATION REALLY STARTS HERE
  strainer.dead=0
  O.run(50000)


  ### python script ###

  
  # -*- coding: utf-8 -*-
  from pylab import *

  ### processing function
  def store(var,textFile):
      data=loadtxt(textFile,skiprows=1)
      it=[]
      e=[]
      s=[]
      tc=[]
      sc=[]
      uf=[]
      for i in range(0,len(data)):
        it.append(float(data[i,1]))
        e.append(-float(data[i,0]))
        s.append(-float(data[i,4]))
        tc.append(float(data[i,5]))
        sc.append(float(data[i,2]))
        uf.append(float(data[i,7]))
      var.append(it)
      var.append(e)
      var.append(s)
      var.append(tc)
      var.append(sc)
      var.append(uf)
     
  ### data input
  dataFile1='compressionTest'
  a1=[]
  store(a1,dataFile1)

  dataFile2='compressionTest_neverErase'
  a2=[]
  store(a2,dataFile2)

  rcParams.update({'legend.numpoints':1,'font.size':20,'axes.labelsize':28,'xtick.major.pad':10,'ytick.major.pad':10,'legend.fontsize':18})

  figure(1,figsize=(10,10))
  xlabel(r'$\epsilon_1$ [millistrain]')
  #axis(xmax=0.1)
  plot([x*1e3 for x in a1[1]],[x/1e6 for x in a1[2]],'-k',linewidth=2)
  plot([x*1e3 for x in a2[1]],[x/1e6 for x in a2[2]],'-r',linewidth=2)
  ylabel(r'$\sigma_1$ [MPa]')
  axis(ymin=0)
  #savefig(dataFile1+'_qVSeps.eps',dpi=1000,format='eps',transparent=False)

  ### show
  show()

To manage notifications about this bug go to:
https://bugs.launchpad.net/yade/+bug/1790167/+subscriptions