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Message #19344
Re: [Question #679566]: Some questions about simulating consolidated undrained triaxial test
Question #679566 on Yade changed:
https://answers.launchpad.net/yade/+question/679566
Cloud posted a new comment:
Hi Robert,
Thanks for your reply!
>>Are you simulating fluid?
No. Instead, to carry out the undrained test during triaxial shear, the
volume of the sample was maintained constant. this is a method to
simulate undrained condition in triaxial test without fluid.
We can check confining stress in file 'results_triax_base_' after
running the MWE, then you will find that the confining stress is
changing.
the MWE:
from yade import pack
nRead=readParamsFromTable(
num_spheres=10000,
compFricDegree = 30 ,
key='_triax_base_',
unknownOk=True
)
from yade.params import table
num_spheres=table.num_spheres
key=table.key
targetPorosity = 0.43
compFricDegree = table.compFricDegree
finalFricDegree = 22
rate=-0.02
damp=0.2
stabilityThreshold=0.01
young=5e6
mn,mx=Vector3(0,0,0),Vector3(10,10,10)
confiningS=400e3
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)
O.bodies.append([sphere(center,rad,material='spheres') for center,rad in sp])
triax=TriaxialStressController(
maxMultiplier=1.+2e4/young,
finalMaxMultiplier=1.+2e3/young,
thickness = 0,
stressMask = 7,
internalCompaction=False,
)
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,truncate=1),
newton
]
Gl1_Sphere.stripes=0
if nRead==0: yade.qt.Controller(), yade.qt.View()
triax.goal1=triax.goal2=triax.goal3=-confiningS
while 1:
O.run(1000, True)
unb=unbalancedForce()
print 'unbalanced force:',unb,' mean stress: ',triax.meanStress
if unb<stabilityThreshold and abs(-confiningS-triax.meanStress)/confiningS<0.001:
break
O.save('confinedState'+key+'.yade.gz')
print "### Isotropic state saved ###"
triax.internalCompaction=False
triax.width0=triax.width
triax.depth0=triax.depth
triax.height0=triax.height
setContactFriction(radians(finalFricDegree))
triax.stressMask=0
triax.goal2= rate
triax.goal1=triax.goal3=-rate/2
newton.damping=0.1
O.saveTmp()
from yade import plot
def history():
plot.addData(
e22=-triax.strain[1], # axial strain
e11=-triax.strain[0],
e33=-triax.strain[2],
ev=triax.volumetricStrain,
s11=-triax.stress(triax.wall_right_id)[0],
s22=-triax.stress(triax.wall_top_id)[1],
s33=-triax.stress(triax.wall_front_id)[2],
args=(-triax.stress(triax.wall_right_id)[0]-triax.stress(triax.wall_top_id)[1]-triax.stress(triax.wall_front_id)[2])/3,
eta = 3*(-triax.stress(triax.wall_top_id)[1]+triax.stress(triax.wall_right_id)[0])/(-triax.stress(triax.wall_right_id)[0]-triax.stress(triax.wall_top_id)[1]-triax.stress(triax.wall_front_id)[2]),
devi = -triax.stress(triax.wall_top_id)[1]+triax.stress(triax.wall_right_id)[0],
i=O.iter,
)
def stoploading():
axial_strain = abs(triax.strain[1])
if axial_strain > 0.3:
print 'axial strain reach Limitation, stop loading!'
O.pause()
if 1:
O.engines=O.engines[0:5]+[PyRunner(iterPeriod=20,command='history()',label='recorder')]+O.engines[5:7]
O.engines=O.engines+[PyRunner(command='stoploading()',iterPeriod=100)]
else:
O.engines[4]=PyRunner(iterPeriod=20,command='history()',label='recorder')
while 1:
O.run(1000,True)
if O.iter%100 == 0:
print "iter = ", O.iter
print "Syy = ",abs(triax.strain[1])
if abs(triax.strain[1]) > 0.3:
break
plot.plots={'e22':('devi',),' args ':('devi')}
plot.plot()
plot.saveDataTxt('results'+key)
plot.saveGnuplot('plotScript'+key)
Cloud
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