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[jamespaul <question678440@xxxxxxxxxxxxxxxxxxxxx>]

New question #678440 on Yade:
https://answers.launchpad.net/yade/+question/678440

Hi,

That's my other question.  (https://answers.launchpad.net/yade/+question/678348)

Let me give another example.Copying script from (https://yade-dev.gitlab.io/trunk/tutorial-examples.html)
 
Using my own custom materials.

materials.append(FrictMat(young=64e9,poisson=0.12,density=2650,frictionAngle=0.23)

In the second compression, change triax.maxStrainRate=(0,0,0).If I adjust young's modulus to young=64e7, it can maintain the stress of the first isotropic compression, otherwise the stress becomes 0.

I wonder why young's modulus can cause such a big change? How can I adjust:)

Thanks

#####################
# encoding: utf-8

sigmaIso=-1e5

#import matplotlib
#matplotlib.use('Agg')

# generate loose packing
from yade import pack, qt, plot

O.periodic=True

sphere=O.materials.append(FrictMat(young=64e9,poisson=0.12,density=2650,frictionAngle=0.23,label='sphere'))
sp=pack.SpherePack()
sp.makeCloud((0,0,0),(2,2,2),rMean=.1,rRelFuzz=.3,periodic=True)
sp.toSimulation()

O.engines=[
	ForceResetter(),
	InsertionSortCollider([Bo1_Sphere_Aabb()]),
	InteractionLoop(
		[Ig2_Sphere_Sphere_ScGeom()],
		[Ip2_FrictMat_FrictMat_FrictPhys()],
		[Law2_ScGeom_FrictPhys_CundallStrack()]
	),
	PeriTriaxController(label='triax',
		# specify target values and whether they are strains or stresses
		goal=(sigmaIso,sigmaIso,sigmaIso),stressMask=7,
		# type of servo-control
		dynCell=True,maxStrainRate=(10,10,10),
		# wait until the unbalanced force goes below this value
		maxUnbalanced=.1,relStressTol=1e-3,
		# call this function when goal is reached and the packing is stable
		doneHook='compactionFinished()'
	),
	NewtonIntegrator(damping=.2),
	PyRunner(command='addPlotData()',iterPeriod=100),
]
O.dt=.5*PWaveTimeStep()

def addPlotData():
	plot.addData(unbalanced=unbalancedForce(),i=O.iter,
		sxx=triax.stress[0],syy=triax.stress[1],szz=triax.stress[2],
		exx=triax.strain[0],eyy=triax.strain[1],ezz=triax.strain[2],
		# save all available energy data
		Etot=O.energy.total(),**O.energy
	)

# enable energy tracking in the code
O.trackEnergy=True

# define what to plot
plot.plots={'i':('unbalanced',),'i ':('sxx','syy','szz'),' i':('exx','eyy','ezz'),
	# energy plot
	' i ':(O.energy.keys,None,'Etot'),
}
# show the plot
plot.plot()

def compactionFinished():
	# set the current cell configuration to be the reference one
	O.cell.trsf=Matrix3.Identity
	# change control type: keep constant confinement in x,y, 20% compression in z
	triax.goal=(sigmaIso,sigmaIso,-.2)
	triax.stressMask=3
	# allow faster deformation along x,y to better maintain stresses
	triax.maxStrainRate=(0,0,0)
	# next time, call triaxFinished instead of compactionFinished
	triax.doneHook='triaxFinished()'
	# do not wait for stabilization before calling triaxFinished
	triax.maxUnbalanced=10

def triaxFinished():
	print 'Finished'
	O.pause()

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