# e1=0.618
# confinement stress / contrainte de confinement = 100000 Pa
# ammount of particles: 1000
from yade import pack
# to create a table to use later
nRead=utils.readParamsFromTable(
num_spheres=1000,# number of spheres (choose little to have faster result)
compFricDegree = 0, # contact friction during the confining phase, to avoid the "effet de voute"
unknownOk=True
)
from yade.params import table # import the table to the data
num_spheres=table.num_spheres # number of spheres
targetPorosity = 0.382 #the porosity we want for the packing [indice des vides e=0.618, n=e/(e+1)]
compFricDegree = table.compFricDegree # initial contact friction during the confining phase (will be decreased during the REFD compaction process)
finalFricDegree = 35 # contact friction during the deviatoric loading
rate=0.001 # loading rate (strain rate) initial value=0.02
damp=0.2 # damping coefficient (initial value=0.2)
stabilityThreshold=0.01 # we test unbalancedForce against this value in different loops (see below)
key='_triax_base_' # put you simulation's name here
young=356e6 # contact stiffness kn/Ds
mn,mx=Vector3(-0.1,-0.1,-0.1),Vector3(0.1,0.1,0.1) # corners of the initial packing // page 87 Luc Sibille
thick = 0.01 # thickness of the plates (chose whatever)
# create materials for spheres and plates
# in this one poisson=k_t/k_n=042
O.materials.append(FrictMat(young=young,poisson=0.42,frictionAngle=radians(compFricDegree),density=3000,label='spheres'))
O.materials.append(FrictMat(young=young,poisson=0.5,frictionAngle=0,density=0,label='walls'))
# the explanation of this definition is at the page 298 in the YADE.pdf
# young and poisson are not always modulus of elasticity and possion coefficient, it depends on the IPhys (look in pdf)
# create walls around the packing
walls=utils.aabbWalls([mn,mx],thickness=thick,material='walls') # one always includes the pair of vectors of dimension, mat and epaisseur
wallIds=O.bodies.append(walls) # add it into modelisation
# use a SpherePack object to generate a random loose particles packing
sp=pack.SpherePack()
#psdSizes=[0.002,0.003,0.004,0.005,0.006,0.007,0.008,0.0092]
#psdCumm=[0.01,0.09,0.25,0.5,0.69,0.9,0.95,1]
psdSizes=[0.002,0.003,0.004,0.005,0.006,0.007,0.008,0.0092]
psdCumm=[1,9,25,50,69,90,95,100]
# sp.makeCloud(mn,mx,0.00575,0.065,num_spheres,False,porosity=0.3819,psdSizes=[0.002,0.003,0.004,0.005,0.006,0.007,0.008,0.0092],psdCumm=[0.01,0.09,0.25,0.5,0.69,0.9,0.95,1],False) # psd method
# if that not works, try the answered question in YADE launchpad
sp.particleSD(mn,mx,0.00575,True,'GiaHien',num_spheres,psdSizes,psdCumm,False,0)
O.bodies.append([utils.sphere(center,rad,material='spheres') for center,rad in sp])
############################
### DEFINING ENGINES ###
############################
triax=ThreeDTriaxialEngine(
maxMultiplier=1.01, # spheres growing factor (fast growth)
finalMaxMultiplier=1.001, # spheres growing factor (slow growth)
thickness = thick,
stressControl_1 = True, #switch stress/strain control
stressControl_2 = False, # on the axis 2 we will use imposed displacement method
stressControl_3 = True, # essayer a garder la contrainte de confinement
## The stress used for (isotropic) internal compaction
sigma_iso = 100000,
## Independant stress values for anisotropic loadings
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
wallDamping=0.8,
)
#comp=TriaxialStressController(
# sigma1=100000,
# sigma3=100000,
#)
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'+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
if unb<stabilityThreshold and abs(meanS-triax.sigma_iso)/triax.sigma_iso<0.001:
break
O.save('confinedState'+key+'.yade.gz')
print "### Isotropic state saved ###"
print "current porosity",triax.porosity
###################################################
### REACHING A SPECIFIED POROSITY PRECISELY ###
###################################################
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()
## while we run steps, triax will tend to grow particles as the packing
## keeps shrinking as a consequence of decreasing friction. Consequently
## porosity will decrease
O.run(500,1)
O.save('compactedState'+key+'.yade.gz')
print "### Compacted state saved ###"
##############################
### DEVIATORIC LOADING ###
##############################
##We move to deviatoric loading, let us turn internal compaction off to keep particles sizes constant
triax.internalCompaction=False
triax.isAxisymetric=True
## Change contact friction (remember that decreasing it would generate instantaneous instabilities)
triax.setContactProperties(finalFricDegree)
## We turn all these flags true, else boundaries will be fixed
triax.wall_bottom_activated=False #fix the bottom plate
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 # for boolean variety, 1 means True and 0 means False
triax.strainRate2=rate
triax.sigma1=100000,
triax.sigma2=0,
triax.sigma3=100000,
#wall_left_id=0 # coordinate 0-
#wall_right_id=1 # coordinate 0+
#wall_bottom_id=2 # coordinate 1-
#wall_top_id=3 # coordinate 1+
#wall_back_id=4 # id of boundary, coordinate 2+
#wall_front_id=5 # coordinate 2+
##Save temporary state in live memory. This state will be reloaded from the interface with the "reload" button.
O.saveTmp()
#####################################################
### 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],
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],
q=abs(triax.stress(triax.wall_top_id)[1]-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')
O.run(100,True)
### declare what is to plot. "None" is for separating y and y2 axis
#plot.plots={'i':('e11','e22','e33',None,'s11','s22','s33')}
### the traditional triaxial curves would be more like this:
# plot.plots={'e22':('s11','s22','s33',None,'ev')}
plot.plots={'e22':'q'}
plot.saveGnuplot('04_withsave'+key) # awesome, save data and plot script at the same time
## display on the screen (doesn't work on VMware image it seems)
plot.plot()
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