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[ceguo <question197775@xxxxxxxxxxxxxxxxxxxxx>]

Question #197775 on Yade changed:
https://answers.launchpad.net/yade/+question/197775

    Status: Solved => Open

ceguo is still having a problem:
Hi Bruno,

After I consolidated the packing using an engine and then sheared it
with velGrad, I got different results with or without using an engine.
But you pointed no need to use an engine, why I got different results?

Besides, if I want to output some results every 1000 steps, I can use
PyRunner. Should PyRunner always be included in an engine?

#================my test script==================================
from yade import pack

O.materials.append(FrictMat(young=150e6,poisson=.3,frictionAngle=.3))
sp = pack.SpherePack()
sp.makeCloud(minCorner=(0,0,0),maxCorner=(20,20,0),rMean=.16,rRelFuzz=.5,num=2000,periodic=True,seed=1)
sp.toSimulation()
O.cell.hSize = Matrix3(20,0,0, 0,20,0, 0,0,1)
for p in O.bodies:
   p.state.blockedDOFs = 'zXY'
   p.state.mass = 2650*pi*p.shape.radius**2
O.dt = .5*utils.PWaveTimeStep()

O.engines = [
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb()]),
   InteractionLoop(
      [Ig2_Sphere_Sphere_Dem3DofGeom()],
      [Ip2_FrictMat_FrictMat_FrictPhys()],
      [Law2_Dem3DofGeom_FrictPhys_CundallStrack()]
   ),
   Peri3dController(
      goal=(-1.e5,-1.e5,0,0,0,0),
      stressMask=0b100011,
      nSteps=20000,
      maxStrain=1.,
      label='consolidation'
   ),
   NewtonIntegrator(damping=.7)
]
O.run()
O.wait()

print utils.stressTensorOfPeriodicCell()

O.materials[0].frictionAngle=.5
dstrain=Matrix3(1.e-2,0,0, 0,-1.e-2,0, 0,0,0)
O.cell.velGrad=dstrain/(20000*O.dt)
#O.engines=[
#   ForceResetter(),
#    InsertionSortCollider([Bo1_Sphere_Aabb()]),
#    InteractionLoop(
#       [Ig2_Sphere_Sphere_Dem3DofGeom()],
#       [Ip2_FrictMat_FrictMat_FrictPhys()],
#       [Law2_Dem3DofGeom_FrictPhys_CundallStrack()]
#    ),
#    NewtonIntegrator(damping=.7)
#]
O.run(20000,True)
print utils.stressTensorOfPeriodicCell()
#=============The end========================================

If I uncomment the scripts of defining the shear engine, I will get same
stress after consolidation (same initial state for shear) but different
stress after shear.

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