New question #226881 on Yade:
https://answers.launchpad.net/yade/+question/226881
As recommended by B Chareyre etc. use TriaxialStressController instead of
ThreeDTriaxialEngine
I still rerun the code in triax-tutorial folder, I find script1 will collapse
with a high strain rate say 2.0, but will not converge with a low strain rate
say 0.02. I used TriaxialStressController instead, a strain rate of 0.02 will
converge, but contact angels can't be changed.
questions is below
1) ThreeDTriaxialEngine does sth different than TriaxialStressController
2) StressControl_1 2 3 with a flag of False seem to force the motion of the
walls, at that time, what does a stressMask do?
script is below
1) ThreeDTriaxialEngine
# -*- coding: utf-8 -*-
from yade import pack
#from utils import *
############################################
### DEFINING VARIABLES AND MATERIALS ###
############################################
# The following 5 lines will be used later for batch execution
nRead=utils.readParamsFromTable(
num_spheres=500,# number of spheres
compFricDegree = 30, # contact friction during the confining phase
unknownOk=True
)
from yade.params import table
num_spheres=table.num_spheres# number of spheres
compFricDegree = table.compFricDegree # contact friction during the confining
phase
finalFricDegree = 30 # contact friction during the deviatoric loading
rate=0.02*40 # loading rate (strain rate)
damp=0.2 # damping coefficient
stabilityThreshold=0.01 # we test unbalancedForce against this value in
different loops (see below)
key='_triax_base_' # put you simulation's name here
young=5e6 # contact stiffness
mn,mx=Vector3(0,0,0),Vector3(1,2,1) # corners of the initial packing
thick = 0.01 # thickness of the plates
## create materials for spheres and plates
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'))
## create walls around the packing
walls=utils.aabbWalls([mn,mx],thickness=thick,material='walls')
wallIds=O.bodies.append(walls)
## use a SpherePack object to generate a random loose particles packing
sp=pack.SpherePack()
sp.makeCloud(mn,mx,-1,0.3333,num_spheres,False, 0.95)
## approximate mean rad of the futur dense packing for latter use (as an
exercise: you can compute exact
volume = (mx[0]-mn[0])*(mx[1]-mn[1])*(mx[2]-mn[2])
mean_rad = pow(0.09*volume/num_spheres,0.3333)
clumps=False
if clumps:
c1=pack.SpherePack([((-0.2*mean_rad,0,0),0.5*mean_rad),((0.2*mean_rad,0,0),0.5*mean_rad)])
sp.makeClumpCloud((0,0,0),(1,1,1),[c1],periodic=False)
O.bodies.append([utils.sphere(center,rad,material='spheres') for
center,rad in sp])
standalone,clumps=sp.getClumps()
for clump in clumps:
O.bodies.clump(clump)
for i in clump[1:]:
O.bodies[i].shape.color=O.bodies[clump[0]].shape.color
#sp.toSimulation()
else:
O.bodies.append([utils.sphere(center,rad,material='spheres') for
center,rad in sp])
O.dt=.5*utils.PWaveTimeStep() # initial timestep, to not explode right away
O.usesTimeStepper=True
############################
### DEFINING ENGINES ###
############################
triax=ThreeDTriaxialEngine(
## ThreeDTriaxialEngine will be used to control stress and strain. It
controls particles size and plates positions.
maxMultiplier=1.+2e4/young, # spheres growing factor (fast growth)
finalMaxMultiplier=1.+2e3/young, # spheres growing factor (slow growth)
thickness = thick,
stressControl_1 = False, #switch stress/strain control
stressControl_2 = False,
stressControl_3 = False,
## The stress used for (isotropic) internal compaction
# sigma_iso = 10000,
## Independant stress values for anisotropic loadings
# sigma1=10000,
# sigma2=10000,
# sigma3=10000,
goal1 = 10000,
goal2 = 10000,
goal3 = 10000,
internalCompaction=True, # If true the confining pressure is generated
by growing particles
Key=key, # passed to the engine so that the output file will have the
correct name
)
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,
defaultDt=4*utils.PWaveTimeStep()),
triax,
TriaxialStateRecorder(iterPeriod=100,file='WallStresses'+key),
newton
]
#Display spheres with 2 colors for seeing rotations better
Gl1_Sphere.stripes=0
if nRead==0: yade.qt.Controller(), yade.qt.View()
#######################################
### APPLYING CONFINING PRESSURE ###
#######################################
while 1:
O.run(1000, True)
##the global unbalanced force on dynamic bodies, thus excluding boundaries,
which are not at equilibrium
unb=unbalancedForce()
##average stress
##note: triax.stress(k) returns a stress vector, so we need to keep only the
normal component
meanS=(triax.stress(triax.wall_right_id)[0]+triax.stress(triax.wall_top_id)[1]+triax.stress(triax.wall_front_id)[2])/3
print 'unbalanced force:',unb,' mean stress: ',meanS
sigma_iso = 10000
if unb<stabilityThreshold and abs(meanS-sigma_iso)/sigma_iso<0.001:
break
O.save('confinedState'+key+'.yade.gz')
print "### Isotropic state saved ###"
##############################
### DEVIATORIC LOADING ###
##############################
##We move to deviatoric loading, let us turn internal compaction off to keep
particles sizes constant
triax.internalCompaction=False
## Change contact friction (remember that decreasing it would generate
instantaneous instabilities)
triax.setContactProperties(finalFricDegree)
##set independant stress control on each axis
triax.stressControl_1=triax.stressControl_2=triax.stressControl_3=True
#triax.stressControl_1=triax.stressControl_2=triax.stressControl_3=0
## We turn all these flags true, else boundaries will be fixed
triax.wall_bottom_activated=True
triax.wall_top_activated=True
triax.wall_left_activated=True
triax.wall_right_activated=True
triax.wall_back_activated=True
triax.wall_front_activated=True
##If we want a triaxial loading at imposed strain rate, let's assign srain rate
instead of stress
triax.stressControl_2=0 #we are tired of typing "True" and "False", we use
implicit conversion from integer to boolean
triax.strainRate2=rate
triax.strainRate1=100*rate
triax.strainRate3=100*rate
#stressMask = 5
#triax.goal2 = 0.02
##we can change damping here. What is the effect in your opinion?
newton.damping=0.1
##Save temporary state in live memory. This state will be reloaded from the
interface with the "reload" button.
O.saveTmp()
#####################################################
### Example of how to record and plot data ###
#####################################################
from yade import plot
### a function saving variables
def history():
plot.addData(e11=triax.strain[0], e22=triax.strain[1],
e33=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)
if 1:
## include a periodic engine calling that function in the simulation loop
O.engines=O.engines[0:5]+[PyRunner(iterPeriod=20,command='history()',label='recorder')]+O.engines[5:7]
##O.engines.insert(4,PyRunner(iterPeriod=20,command='history()',label='recorder'))
else:
## With the line above, we are recording some variables twice. We could in
fact replace the previous
## TriaxialRecorder
## by our periodic engine. Uncomment the following line:
O.engines[4]=PyRunner(iterPeriod=20,command='history()',label='recorder')
while 1:
O.run(1000,True)
if O.iter%1000 == 0:
print 'iter = ',O.iter, 'Syy = ',triax.strain[1]
if triax.strain[1] > .1:
break
### declare what is to plot. "None" is for separating y and y2 axis
plot.plots={'i':('e11','e22','e33',None,'s11','s22','s33')}
##display on the screen (doesn't work on VMware image it seems)
##plot.plot()
## In that case we can still save the data to a text file at the the end of the
simulation, with:
plot.saveDataTxt('results'+key)
##or even generate a script for gnuplot. Open another terminal and type
"gnuplot plotScriptKEY.gnuplot:
plot.saveGnuplot('plotScript'+key)
2) TriaxialStressController
# -*- coding: utf-8 -*-
from yade import pack
#from utils import *
############################################
### DEFINING VARIABLES AND MATERIALS ###
############################################
# The following 5 lines will be used later for batch execution
nRead=utils.readParamsFromTable(
num_spheres=500,# number of spheres
compFricDegree = 30, # contact friction during the confining phase
unknownOk=True
)
from yade.params import table
num_spheres=table.num_spheres# number of spheres
compFricDegree = table.compFricDegree # contact friction during the confining
phase
finalFricDegree = 30 # contact friction during the deviatoric loading
rate=0.02*10 # loading rate (strain rate)
damp=0.2 # damping coefficient
stabilityThreshold=0.01 # we test unbalancedForce against this value in
different loops (see below)
key='_triax_base_' # put you simulation's name here
young=5e6 # contact stiffness
mn,mx=Vector3(0,0,0),Vector3(1,2,1) # corners of the initial packing
thick = 0.01 # thickness of the plates
## create materials for spheres and plates
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'))
## create walls around the packing
walls=utils.aabbWalls([mn,mx],thickness=thick,material='walls')
wallIds=O.bodies.append(walls)
## use a SpherePack object to generate a random loose particles packing
sp=pack.SpherePack()
sp.makeCloud(mn,mx,-1,0.3333,num_spheres,False, 0.95)
## approximate mean rad of the futur dense packing for latter use (as an
exercise: you can compute exact
volume = (mx[0]-mn[0])*(mx[1]-mn[1])*(mx[2]-mn[2])
mean_rad = pow(0.09*volume/num_spheres,0.3333)
clumps=False
if clumps:
c1=pack.SpherePack([((-0.2*mean_rad,0,0),0.5*mean_rad),((0.2*mean_rad,0,0),0.5*mean_rad)])
sp.makeClumpCloud((0,0,0),(1,1,1),[c1],periodic=False)
O.bodies.append([utils.sphere(center,rad,material='spheres') for
center,rad in sp])
standalone,clumps=sp.getClumps()
for clump in clumps:
O.bodies.clump(clump)
for i in clump[1:]:
O.bodies[i].shape.color=O.bodies[clump[0]].shape.color
#sp.toSimulation()
else:
O.bodies.append([utils.sphere(center,rad,material='spheres') for
center,rad in sp])
O.dt=.5*utils.PWaveTimeStep() # initial timestep, to not explode right away
O.usesTimeStepper=True
############################
### DEFINING ENGINES ###
############################
triax=TriaxialStressController(
## ThreeDTriaxialEngine will be used to control stress and strain. It
controls particles size and plates positions.
maxMultiplier=1.+2e4/young, # spheres growing factor (fast growth)
finalMaxMultiplier=1.+2e3/young, # spheres growing factor (slow growth)
thickness = thick,
# stressControl_1 = False, #switch stress/strain control
# stressControl_2 = False,
# stressControl_3 = False,
## The stress used for (isotropic) internal compaction
# sigma_iso = 10000,
## Independant stress values for anisotropic loadings
# sigma1=10000,
# sigma2=10000,
# sigma3=10000,
goal1 = 10000,
goal2 = 10000,
goal3 = 10000,
stressMask = 7,
internalCompaction=True, # If true the confining pressure is generated
by growing particles
# Key=key, # passed to the engine so that the output file will have the
correct name
)
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,
defaultDt=4*utils.PWaveTimeStep()),
triax,
TriaxialStateRecorder(iterPeriod=100,file='WallStresses'+key),
newton
]
#Display spheres with 2 colors for seeing rotations better
Gl1_Sphere.stripes=0
#if nRead==0: yade.qt.Controller(), yade.qt.View()
#######################################
### APPLYING CONFINING PRESSURE ###
#######################################
while 1:
O.run(1000, True)
##the global unbalanced force on dynamic bodies, thus excluding boundaries,
which are not at equilibrium
unb=unbalancedForce()
##average stress
##note: triax.stress(k) returns a stress vector, so we need to keep only the
normal component
meanS=(triax.stress(triax.wall_right_id)[0]+triax.stress(triax.wall_top_id)[1]+triax.stress(triax.wall_front_id)[2])/3
print 'unbalanced force:',unb,' mean stress: ',meanS
sigma_iso = 10000
if unb<stabilityThreshold and abs(meanS-sigma_iso)/sigma_iso<0.001:
break
O.save('confinedState'+key+'.yade.gz')
print "### Isotropic state saved ###"
##############################
### DEVIATORIC LOADING ###
##############################
##We move to deviatoric loading, let us turn internal compaction off to keep
particles sizes constant
triax.internalCompaction=False
## Change contact friction (remember that decreasing it would generate
instantaneous instabilities)
#triax.setContactProperties(finalFricDegree)
##set independant stress control on each axis
triax.stressControl_1=triax.stressControl_2=triax.stressControl_3=True
## We turn all these flags true, else boundaries will be fixed
triax.wall_bottom_activated=True
triax.wall_top_activated=True
triax.wall_left_activated=True
triax.wall_right_activated=True
triax.wall_back_activated=True
triax.wall_front_activated=True
##If we want a triaxial loading at imposed strain rate, let's assign srain rate
instead of stress
triax.stressControl_2=0 #we are tired of typing "True" and "False", we use
implicit conversion from integer to boolean
triax.stressMask = 5
triax.goal2 = 0.02
#triax.strainRate2=rate
#triax.strainRate1=100*rate
#triax.strainRate3=100*rate
##we can change damping here. What is the effect in your opinion?
newton.damping=0.1
##Save temporary state in live memory. This state will be reloaded from the
interface with the "reload" button.
O.saveTmp()
#####################################################
### Example of how to record and plot data ###
#####################################################
from yade import plot
### a function saving variables
def history():
plot.addData(e11=triax.strain[0], e22=triax.strain[1],
e33=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)
if 1:
## include a periodic engine calling that function in the simulation loop
O.engines=O.engines[0:5]+[PyRunner(iterPeriod=20,command='history()',label='recorder')]+O.engines[5:7]
##O.engines.insert(4,PyRunner(iterPeriod=20,command='history()',label='recorder'))
else:
## With the line above, we are recording some variables twice. We could in
fact replace the previous
## TriaxialRecorder
## by our periodic engine. Uncomment the following line:
O.engines[4]=PyRunner(iterPeriod=20,command='history()',label='recorder')
while 1:
O.run(1000,True)
if O.iter%1000 == 0:
print 'iter = ',O.iter, 'Syy = ',-triax.strain[1]
if -triax.strain[1] > .2:
break
### declare what is to plot. "None" is for separating y and y2 axis
plot.plots={'i':('e11','e22','e33',None,'s11','s22','s33')}
##display on the screen (doesn't work on VMware image it seems)
##plot.plot()
## In that case we can still save the data to a text file at the the end of the
simulation, with:
plot.saveDataTxt('results'+key)
##or even generate a script for gnuplot. Open another terminal and type
"gnuplot plotScriptKEY.gnuplot:
plot.saveGnuplot('plotScript'+key)
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