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[Chu <question691193@xxxxxxxxxxxxxxxxxxxxx>]

Question #691193 on Yade changed:
https://answers.launchpad.net/yade/+question/691193

    Status: Needs information => Open

Chu gave more information on the question:
Dear Robert,

Thank you for your suggestion. I used non-periodic boundary and I got
TW_Volume=1.0451466106445113, when the volume of pack is 1.0. It seems
better but error still exists.

In addition, I got different result when I set different young, such as

TW_Volume=1.045146610644511 #young=1e6
TW_Volume=1.000684823430585 #young=1e8
TW_Volume=1.000056824921447 #young=1e10

It's interesting, the larger the young, the smaller the error.

####MWE####

from yade import pack

num_spheres=1000# number of spheres
young=1e6
compFricDegree = 3 # initial contact friction during the confining phase
mn,mx=Vector3(0,0,0),Vector3(1,1,1) # corners of the initial packing

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'))
walls=aabbWalls([mn,mx],thickness=0,material='walls')
wallIds=O.bodies.append(walls)

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

triax=TriaxialStressController(
	maxMultiplier=1.+2e4/young, # spheres growing factor (fast growth)
	finalMaxMultiplier=1.+2e3/young, # spheres growing factor (slow growth)
	thickness = 0,
	stressMask = 7,
	internalCompaction=True, # If true the confining pressure is generated by growing particles
)

newton=NewtonIntegrator(damping=0.2)

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()],label="iloop"
	),
	GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),
	triax,
	newton
]

triax.goal1=triax.goal2=triax.goal3=-10000

while 1:
  O.run(1000, True)
  unb=unbalancedForce()
  if unb<0.001 and abs(-10000-triax.meanStress)/10000<0.001:
    break


TW=TesselationWrapper()
TW.triangulate()
TW.setState()
TW.computeVolumes()

TW_Volume=0
for b in O.bodies:
    if isinstance(b.shape,Sphere):
        TW_Volume += TW.volume(b.id)

print('TW_Volume='+str(TW_Volume))

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