setCohesionNow & setCohesionOnNewContacts /triaxial test

Asked by Seti

Hello all,

can I turn on setCohesionNow, setCohesionOnNewContacts in triaxial test as well? if yes, why I set these parameters the porosity & friction does not change and I face with below error? while without these consideration code works.

 "Friction: 33.25 porosity: 1.0python: malloc.c:3720: _int_malloc: Assertion `(unsigned long) (size) >= (unsigned long) (nb)' failed.
Aborted (core dumped)"

the triaxial script is not different from the original one, I just copy it here if you need to know about the inputs.

Thanks,
Seti

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 =35, # 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 = 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=-0.005 # loading rate (strain rate)
damp=0.3 # damping coefficient
stabilityThreshold=0.01 # we test unbalancedForce against this value in different loops (see below)
young=100e6# 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=0.09,frictionAngle=radians(33.5),normalCohesion=7.5e3,shearCohesion=2.25e3,momentRotationLaw=True,etaRoll=0.001,density=2600,isCohesive=True,label='spheres'))
O.materials.append(CohFrictMat(young=young,poisson=0,frictionAngle=radians(0),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,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(setCohesionNow = True, setCohesionOnNewContacts = 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=False, #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='150,damp0.8,rate 0.005,NEW50,alphaKr=0.5,young=100e6,poisson=0.09,frictionAngle=radians(50),normalCohesion=7.5e10,shearCohesion=2.25e10,etaRoll=0.025,density=2600,wall35,'+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=-150000

#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=-150000
triax.goal3=-150000

##we can change damping here. What is the effect in your opinion?
newton.damping=0.1

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Revision history for this message
Jérôme Duriez (jduriez) said :
#1

Hi,

Why did you choose to define two Ip2 and two Law2 in the InteractionLoop ?
Note the correct definition of InteractionLoop is explained in https://yade-dem.org/doc/user.html#functors-choice.

Also, there actually is a preprocessor for cohesive triaxial test simulations (see the GUI or [*]). You may just launch it and compare the engines list with yours.

[*] https://yade-dem.org/doc/yade.wrapper.html?highlight=cohesive%20triaxial#yade.wrapper.CohesiveTriaxialTest

Revision history for this message
Bruno Chareyre (bruno-chareyre) said :
#2

Hi,
It seems like a bug. Could you please report the error you get with a debug build?
Bruno

p.s. @Jérôme, I don't see a problem in having multiple functors of each type (although not necessary in this case), that is how yade is supposed to work.

Revision history for this message
Jérôme Duriez (jduriez) said :
#3

My point was that I think cohesive simulations in yade are not supposed to use at the same time CohFrictPhys and FrictPhys ;-)

Revision history for this message
Seti (seti) said :
#4

Hi Jerome and Bruno,

I have submitted a report on bug.

Thanks,
Seti

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