New question #231380 on Yade:
https://answers.launchpad.net/yade/+question/231380
Dear Christian Jakob and all users:
Thanks for the suggestions you gave me. So I have taken a correct running
of my 2D biaxial compression simulation but still have some questions about the
curve of deviatoric stress versus axial strain. The link of my result image is
http://i.imgur.com/TRgetm4.jpg.
As a student DEM researcher, lack of experience makes me hard to
understand this result, in which the values of deviatoric stress are not
smooth, that can fluctuate with the increase of axial-strain. But in this paper
"DEM Modeling and Geotechnical Applications" from Bruno Chareyre, the same
curve can be described as http://i.imgur.com/cgd7UHR.jpg.
This paper notice that the difference between the quasistatic limit and
the apparent peak stress from the simulation can be controlled if the strain
rate is small enough. But I think that the strain rate is not the only reason
for this problem occuring, there may be some other factors that can effect this
result such as material, confining pressure, damping, contact law or
calculation step. So I upload some important details of my whole script and ask
your help!
##################################################################################################
(1).material def:
clumpsmat =
O.materials.append(FrictMat(poisson=0.5,density=250000,young=1e10,frictionAngle=0.5))
wallmat =
O.materials.append(FrictMat(poisson=0.5,density=250000,young=1e10,frictionAngle=0))
##################################################################################################
(2).confining def:
triax01=TriaxialStressController(
wall_bottom_id=wallids[2],wall_top_id=wallids[3],
wall_left_id=wallids[0],wall_right_id=wallids[1],
wall_back_id=wallids[4],wall_front_id=wallids[5],
wall_front_activated = False,wall_back_activated = False,
internalCompaction=False,
stressMask=7,
goal1=50000,
goal2=50000,
goal3=50000,
max_vel=5,
)##################################################################################################
(3).2D biaxial compression def:
triax02=TriaxialStressController(
wall_bottom_id=wallids[2],wall_top_id=wallids[3],
wall_left_id=wallids[0],wall_right_id=wallids[1],
wall_back_id=wallids[4],wall_front_id=wallids[5],
wall_front_activated = False,wall_back_activated = False,
internalCompaction=False,
stressMask = 5,
goal2= -0.1,
goal1=50000,
goal3=50000,
)#################################################################################################
(4)engine def:
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb(),Bo1_Wall_Aabb()]),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_ScGeom_FrictPhys_CundallStrack()]
),
GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),
triax02,
NewtonIntegrator(damping=.4),
]################################################################################################
(5).calculation step def:
dt = 1e-4 (but not working, it uses "p-wave" and the value of it in simulation
is 6.6e-6)
#################################################################################################
How to modify these parameters, seeking your help!
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