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[kalogeropoulos <question676639@xxxxxxxxxxxxxxxxxxxxx>]

New question #676639 on Yade:
https://answers.launchpad.net/yade/+question/676639

Hi to all, 

currently i am trying to perform simulation of UCS and TS as in the paper <<A DEM model for soft and hard rocks: Role of grain interlocking on strength >> of Luc Scholtes and Frédéric-Victor Donzé.

I took the file from trunk/examples/concrete/uniax.py and change the model from CpmMat to JCFpmMat.
Also i took the microparameters from table 2 in the above paper and put it in my script.

Some Remarks i saw in my simulation:
As i put intRadius=1 as in table 2, my Coordination number is 3.37 byt in paper is 6.1
Number of elements: 17412
And Fc = 1.36e06 .
Am i doing something wrong?
 Please have a look in my code :


#!/usr/bin/python
# -*- coding: utf-8 -*-
from __future__ import division

from yade import plot,pack,timing
import time, sys, os, copy

#import matplotlib
#matplotlib.rc('text',usetex=True)

# default parameters or from table
readParamsFromTable(noTableOk=True, # unknownOk=True,
    density=2640,
	young=230e9,
	poisson=2.5,
	frictionAngle=25,
	tensileStrength=22e6,
	cohesion=220e6, #10*tensileStrength,
	
	sphereRadius=1.25e-3,
	rRelFuzz=0.34,
	
	intRadius=1,
	dtSafety=.8,
	damping=0.6,
	strainRateTension=.05,
	strainRateCompression=.5,
	setSpeeds=True,
	# 1=tension, 2=compression (ANDed; 3=both)
	doModes=2,

	# isotropic confinement (should be negative)
	isoPrestress=0,
)

from yade.params.table import *

if 'description' in O.tags.keys(): O.tags['id']=O.tags['id']+O.tags['description']

sample = O.materials.append(JCFpmMat(young=young, poisson=poisson, frictionAngle=radians(frictionAngle), cohesion=cohesion, tensileStrength=tensileStrength,density = density, label='spheres'))

sps=SpherePack()


sp=pack.randomDensePack(pack.inAlignedBox((-25e-3,-25e-3,-62.5e-3),(25e-3,25e-3,62.5e-3)),spheresInCell=2000,radius=sphereRadius,rRelFuzz=rRelFuzz,memoizeDb=False,returnSpherePack=True) #'/tmp/triaxPackCache.sqlite'

sp.toSimulation(color=(1.09,1.0,0.0),material=sample) #color=(1.09,1.0,0.0)

bb=uniaxialTestFeatures()
negIds,posIds,axis,crossSectionArea=bb['negIds'],bb['posIds'],bb['axis'],bb['area']

O.dt=dtSafety*PWaveTimeStep()
print 'Timestep',O.dt


mm,mx=[pt[axis] for pt in aabbExtrema()]
coord_25,coord_50,coord_75=mm+.25*(mx-mm),mm+.5*(mx-mm),mm+.75*(mx-mm)
area_25,area_50,area_75=approxSectionArea(coord_25,axis),approxSectionArea(coord_50,axis),approxSectionArea(coord_75,axis)

O.engines=[
	ForceResetter(),
	InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=intRadius,label='is2aabb')],verletDist=.05*sphereRadius),
	InteractionLoop(
		[Ig2_Sphere_Sphere_ScGeom(interactionDetectionFactor=intRadius,label='ss2sc')],
        [Ip2_JCFpmMat_JCFpmMat_JCFpmPhys(cohesiveTresholdIteration=1)],
        [Law2_ScGeom_JCFpmPhys_JointedCohesiveFrictionalPM(Key='cracks',recordCracks=True,cracksFileExist=True,label='interactionLaw')], 
    ),
    GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),
    UniaxialStrainer(strainRate=strainRateTension,axis=axis,asymmetry=0,posIds=posIds,negIds=negIds,crossSectionArea=crossSectionArea,blockDisplacements=False,blockRotations=False,setSpeeds=setSpeeds,label='strainer'),
    NewtonIntegrator(damping=damping,label='damper'),
        VTKRecorder(fileName='3d-vtk-',recorders=['intr','cracks','jcfpm','facets','spheres','colors'],Key='cracks', realPeriod=50),
	PyRunner(virtPeriod=1e-6/strainRateTension,realPeriod=1,command='addPlotData()',label='plotDataCollector',initRun=True),
	PyRunner(realPeriod=4,command='stopIfDamaged()',label='damageChecker'),
]

plot.plots={'eps':('sigma',)}

O.saveTmp('initial');

O.timingEnabled=False

global mode
mode='tension' if doModes & 1 else 'compression'

def initTest():
	global mode
	print "init"
	if O.iter>0:
		O.wait();
		O.loadTmp('initial')
		print "Reversing plot data"; plot.reverseData()
	else: plot.plot(subPlots=False)
	strainer.strainRate=abs(strainRateTension) if mode=='tension' else -abs(strainRateCompression)
	try:
		from yade import qt
		renderer=qt.Renderer()
		renderer.dispScale=(1000,1000,1000) if mode=='tension' else (100,100,100)
	except ImportError: pass
	print "init done, will now run."
	O.step(); # to create initial contacts
	# now reset the interaction radius and go ahead
	ss2sc.interactionDetectionFactor=1.
	is2aabb.aabbEnlargeFactor=1.

	O.run()

def stopIfDamaged():
	global mode
	if O.iter<2 or not plot.data.has_key('sigma'): return # do nothing at the very beginning
	sigma,eps=plot.data['sigma'],plot.data['eps']
	extremum=max(sigma) if (strainer.strainRate>0) else min(sigma)
	minMaxRatio=0.5 if mode=='tension' else 0.5
	if extremum==0: return
	import sys;	sys.stdout.flush()
	if abs(sigma[-1]/extremum)<minMaxRatio or abs(strainer.strain)>(5e-3 if isoPrestress==0 else 5e-2):
		if mode=='tension' and doModes & 2: # only if compression is enabled
			mode='compression'
			O.save('uniax-tension.yade.gz')
			print "Saved /tmp/uniax-tension.yade.gz (for use with interaction-histogram.py and uniax-post.py)"
			print "Damaged, switching to compression... "; O.pause()
			# important! initTest must be launched in a separate thread;
			# otherwise O.load would wait for the iteration to finish,
			# but it would wait for initTest to return and deadlock would result
			import thread; thread.start_new_thread(initTest,())
			return
		else:
			print "Damaged, stopping."
			ft,fc=max(sigma),min(sigma)
			print 'Strengths fc=%g, ft=%g, |fc/ft|=%g'%(fc,ft,abs(fc/ft))
			title=O.tags['description'] if 'description' in O.tags.keys() else O.tags['params']
			print 'gnuplot',plot.saveGnuplot(O.tags['id'],title=title)
			print 'Bye.'
			O.pause()
			#sys.exit(0) # results in some threading exception
			
def addPlotData():
	yade.plot.addData({'t':O.time,'i':O.iter,'eps':strainer.strain,'sigma':strainer.avgStress+isoPrestress,
		'sigma.25':forcesOnCoordPlane(coord_25,axis)[axis]/area_25+isoPrestress,
		'sigma.50':forcesOnCoordPlane(coord_50,axis)[axis]/area_50+isoPrestress,
		'sigma.75':forcesOnCoordPlane(coord_75,axis)[axis]/area_75+isoPrestress,
		})
plot.plot(subPlots=False)
#O.run()
initTest()

Thank You!!

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