Triaxial sphere packing and .stl geometry

Asked by Luis Barbosa

Hi,
Is it possible use triaxial sphere packing and an imported .stl geometry at the same script?
I'm doing it, but occurs some distortion in my geometry.

Tks.,
Luis

Question information

Language:
English Edit question
Status:
Expired
For:
Yade Edit question
Assignee:
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Luis Barbosa (luis-pires-b) said :
#2

Hi,
For the YADE 1.12 in Ubuntu 14.04LTS, the script with triax compression and a geometry .stl doesn't work.
The same script for YADE 1.07 in Ubuntu 12.04LTS worked.

Tks,
Luis

Revision history for this message
Bruno Chareyre (bruno-chareyre) said :
#3

Hello Luis,
I don't understand the initial question sorry.
Regarding #2, we don't know what script you refer to, nor the meaning of "doesn't work".
I suggest to elaborate a bit more, else nobody can help.
Bruno

Revision history for this message
Luis Barbosa (luis-pires-b) said :
#4

Sorry Bruno,
I'm using Triax and an imported geometry .stl in the same script:

#!/usr/bin/python
# -*- coding: utf-8 -*-

############################################
### DEFINING VARIABLES AND MATERIALS ###
############################################
# The following 5 lines will be used later for batch execution
nRead=readParamsFromTable(
 num_spheres=10000,# number of spheres
 compFricDegree = 30, # 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 = 0.45 #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 = 30 # contact friction during the deviatoric loading
rate=0.02 # loading rate (strain rate)
damp=0.2 # damping coefficient
stabilityThreshold=0.01 # we test unbalancedForce against this value in different loops (see below)
young=5e6 # contact stiffness
mn,mx=Vector3(-0.1,0,-0.1),Vector3(0.1,0.3,0.1) # corners of the initial packing

## 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=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,-1,0.03333,num_spheres,False, 0.85,seed=1) #"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)

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
#######################################
### 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=10000
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('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
## Change contact friction (remember that decreasing it would generate instantaneous instabilities)
setContactFriction(radians(finalFricDegree))

from yade import ymport
mesh = 'coneplanosimulationmeters'
rod = O.bodies.append(ymport.stl('rod-'+mesh+'.stl',wire=False,material='walls'))
O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb(),Bo1_Box_Aabb()]),
   InteractionLoop(
      # handle sphere+sphere and facet+sphere collisions
 [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
 [Ip2_FrictMat_FrictMat_FrictPhys()],
 [Law2_ScGeom_FrictPhys_CundallStrack()]
   ),
   NewtonIntegrator(gravity=(0,-9.81,0),damping=0.6),
   TranslationEngine(ids=rod,translationAxis=[0,-1,0],velocity=0.1),
]

But for YADE 1.12 in Ubuntu 14.04LTS didn't work.

Luis

Revision history for this message
Launchpad Janitor (janitor) said :
#5

This question was expired because it remained in the 'Open' state without activity for the last 15 days.