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Re: [Question #658735]: Triaxial (CD)

To: yade-users@xxxxxxxxxxxxxxxxxxx
From: SayedHessam <question658735@xxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 28 Sep 2017 03:14:28 -0000
Reply-to: question658735@xxxxxxxxxxxxxxxxxxxxx
Sender: bounces@xxxxxxxxxxxxx
Question #658735 on Yade changed:
https://answers.launchpad.net/yade/+question/658735

Description changed to:
Hi guys!

I am trying to calibrate a triaxial model with the real triaxial test. I am using the attached paper for calibration:
"Simulation of a triaxial response of granular materials by modified DEM".

I modified the triaxial script from trunk/examples/triax-tutorial
/script-session1.py for CD test.

The soil is sand without any cohesion.

I have modified the script based on my info that I have and everything
looks correct. However, when I run the model  I have faced an error as
follows:

Traceback (most recent call last):
  File "/usr/bin/yade", line 182, in runScript
    execfile(script,globals())
  File "cdseti.py", line 179, in <module>
    setContactFriction(radians(finalFricDegree))
NameError: name 'finalFricDegree' is not defined 

Therefore, I completely deleted from the script.  Do you think it will
affect my model?

Also, I try to model triaxial (CD), I would like to ask you this is the
correct model for CD or not?


Would you please advise me.

Best Regards
Sam

Here is my code:

# -*- coding: utf-8 -*-


from yade import pack,plot


############################################

### DEFINING VARIABLES AND MATERIALS ###

############################################


# The following 5 lines will be used later for batch execution

nRead=readParamsFromTable(

 num_spheres=1000,# number of spheres

 compFricDegree =36.28, # 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 = 0.42 #the porosity we want for the packing

compFricDegree = 40# contact friction during the deviatoric loading

rate=-0.2 # loading rate (strain rate)

damp=0.3 # damping coefficient

stabilityThreshold=0.01 # we test unbalancedForce against this value in
different loops (see below)

young=80e6# contact stiffness

mn,mx=Vector3(0,0,0),Vector3(0.09,0.18,0.09) # corners of the initial
packing


## create materials for spheres and plates

O.materials.append(CohFrictMat(alphaKr=0.5,young=young,poisson=0.25,frictionAngle=radians(40),normalCohesion=0,shearCohesion=2.25e1,momentRotationLaw=True,etaRoll=0.001,density=2600,isCohesive=True,label='spheres'))

O.materials.append(CohFrictMat(young=young,poisson=0.25,frictionAngle=radians(40),density=0,label='walls'))


## create walls around the packing

walls=aabbWalls([mn,mx],thickness=0,material='walls')

wallIds=O.bodies.append(walls)


## use a SpherePack object to generate a random loose particles packing

sp=pack.SpherePack()


clumps=False #turn this true for the same example with clumps

if clumps:

 ## approximate mean rad of the futur dense packing for latter use

 volume = (mx[0]-mn[0])*(mx[1]-mn[1])*(mx[2]-mn[2])

 mean_rad = pow(0.09*volume/num_spheres,0.3333)

 ## define a unique clump type (we could have many, see clumpCloud
documentation)

c1=pack.SpherePack([((-0.2*mean_rad,0,0),0.5*mean_rad),((0.2*mean_rad,0,0),0.5*mean_rad)])

 ## generate positions and input them in the simulation

 sp.makeClumpCloud(mn,mx,[c1],periodic=False)

 sp.toSimulation(material='spheres')

 O.bodies.updateClumpProperties()#get more accurate clump
masses/volumes/inertia

else:

 sp.makeCloud(mn,mx,-1,0.3333,num_spheres,False, 0.95,seed=1) #"seed"
make the "random" generation always the same

 #sp.makeCloud(mn,mx,0.066,num_spheres) #"seed" make the "random"
generation always the same

 O.bodies.append([sphere(center,rad,material='spheres') for center,rad
in sp])

 #or alternatively (higher level function doing exactly the same):

 #sp.toSimulation(material='spheres')


############################

### DEFINING ENGINES ###

############################


triax=TriaxialStressController(

 ## TriaxialStressController will be used to control stress and strain.
It controls particles size and plates positions.

 ## this control of boundary conditions was used for instance in
http://dx.doi.org/10.1016/j.ijengsci.2008.07.002

 maxMultiplier=1.+2e4/young, # spheres growing factor (fast growth)

 finalMaxMultiplier=1.+2e3/young, # spheres growing factor (slow growth)

 thickness = 0,

 ## switch stress/strain control using a bitmask. What is a bitmask,
huh?!

 ## Say x=1 if stess is controlled on x, else x=0. Same for for y and z,
which are 1 or 0.

 ## Then an integer uniquely defining the combination of all these tests
is: mask = x*1 + y*2 + z*4

 ## to put it differently, the mask is the integer whose binary
representation is xyz, i.e.

 ## "100" (1) means "x", "110" (3) means "x and y", "111" (7) means "x
and y and z", etc.

 stressMask = 7,

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

)


newton=NewtonIntegrator(damping=damp)

########################################

#Modified engine

##################################

O.engines=[

        ForceResetter(),

        InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]),

        InteractionLoop(

                [Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],

[Ip2_FrictMat_FrictMat_FrictPhys(),Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(label="cohesiveIp")],

#[Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=True,label="cohesiveIp")],

[Law2_ScGeom_FrictPhys_CundallStrack(),Law2_ScGeom_CohFrictPhys_CohesionMoment(

   useIncrementalForm=True, #useIncrementalForm is turned on as we want
plasticity on the contact moments

   always_use_moment_law=True, #if we want "rolling" friction even if
the contact is not cohesive (or cohesion is broken), we will have to
turn this true somewhere

   label='cohesiveLaw')]

  #[Law2_ScGeom_CohFrictPhys_CohesionMoment(

   #useIncrementalForm=True, #useIncrementalForm is turned on as we want
plasticity on the contact moments

   #always_use_moment_law=True, #if we want "rolling" friction even if
the contact is not cohesive (or cohesion is broken), we will have to
turn this true somewhere

   #label='cohesiveLaw')]

        ),

        ## We will use the global stiffness of each body to determine an
optimal timestep (see https://yade-
dem.org/w/images/1/1b/Chareyre&Villard2005_licensed.pdf)

GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),

        triax,

        TriaxialStateRecorder(iterPeriod=100,file='150e3,test orig
229,damp0.3,rate
0.005,NEW50,alphaKr=0.5,young80,e1e1,poisson=0.25,frictionAngle=radians(40),,etaRoll=0.025,density=2600,wall36.28,'+key),

        newton

]


##########################################################

#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()]

 #),

 ## We will use the global stiffness of each body to determine an
optimal timestep (see https://yade-
dem.org/w/images/1/1b/Chareyre&Villard2005_licensed.pdf)

#GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),

 #triax,

 #TriaxialStateRecorder(iterPeriod=100,file='WallStresses'+table.key),

 #newton

#]

#############################

#Display spheres with 2 colors for seeing rotations better

Gl1_Sphere.stripes=0

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


## UNCOMMENT THE FOLLOWING SECTIONS ONE BY ONE

## DEPENDING ON YOUR EDITOR, IT COULD BE DONE

## BY SELECTING THE CODE BLOCKS BETWEEN THE SUBTITLES

## AND PRESSING CTRL+SHIFT+D

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

print 'Number of elements: ', len(O.bodies)

print 'Box Volume: ', triax.boxVolume

#######################################

### APPLYING CONFINING PRESSURE ###

#######################################


#the value of (isotropic) confining stress defines the target stress to
be applied in all three directions

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


#while 1:

  #O.run(1000, True)

  ##the global unbalanced force on dynamic bodies, thus excluding
boundaries, which are not at equilibrium

  #unb=unbalancedForce()

  #print 'unbalanced force:',unb,' mean stress: ',triax.meanStress

  #if unb<stabilityThreshold and
abs(-10000-triax.meanStress)/10000<0.001:

    #break


#O.save('confinedState'+key+'.yade.gz')

#print "### Isotropic state saved ###"


###################################################

### REACHING A SPECIFIED POROSITY PRECISELY ###

###################################################


### We will reach a prescribed value of porosity with the REFD algorithm

### (see http://dx.doi.org/10.2516/ogst/2012032 and

###
http://www.geosyntheticssociety.org/Resources/Archive/GI/src/V9I2/GI-V9-N2-Paper1.pdf)


#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('compactedStateBEL20,young=63.9e8'+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


## Change contact friction (remember that decreasing it would generate
instantaneous instabilities)

setContactFriction(radians(finalFricDegree))


##set stress control on x and z, we will impose strain rate on y

triax.stressMask = 5

##now goal2 is the target strain rate

triax.goal2=rate

## we define the lateral stresses during the test, here the same 10kPa
as for the initial confinement.

triax.goal1=-100000

triax.goal3=-100000


##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],

        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)


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':('s11','s22')}


## display on the screen (doesn't work on VMware image it seems)

plot.plot()


##### PLAY THE SIMULATION HERE WITH "PLAY" BUTTON OR WITH THE COMMAND
O.run(N) #####


## In that case we can still save the data to a text file at the the end
of the simulation, with:

plot.saveDataTxt('resultsBEL20,young=63.9e82222'+key)

##or even generate a script for gnuplot. Open another terminal and type
"gnuplot plotScriptKEY.gnuplot:

plot.saveGnuplot('plotScriptBEL20,young=63.9e8222'+key)

rr=yade.qt.Renderer()

rr.shape=False

rr.intrPhys=True

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