Can't reach isotropic state in 2D biaxial compression
Hi,
I am trying to conduct a 2D biaxial compression test by blocking the freedom along z-axis.
I want to make a 2D sample with 70 mm width and 140 mm height and reach the isotropic state of 100 kPa. Learn from previous answers, I come to the following MWE and I meet the followoing problems.
1. It is strange that the stress of top wall and right wall always go to 150 kPa (and keep constant around 150 kPa) even if I set the confining pressure as 100 kPa. Did I set something wrong with the TriaxialStressC
I guess it might be related to the maxMultiplier and finalMaxMultiplier, I also tried by using more smaller Multiplier but I still couldn't gain the desired stress state.
2. One more thing that I'd like to confirm when I review the question [1] : In 2D biaxial test, is the mean stress the average of (top + right) or averge of (top+front+right)? In the MWE below, I use average of (top + right).
Here the MWE:
from yade import pack, plot
num_spheres = 500
compFricDegree = 30
finalFricDegree = 18
rate = 0.01
damp = 0.1
stabilityThreshold = 0.001
young = 5e6
mn,mx=Vector3(
key = 'biax'
confinement=100e3
O.materials.
O.materials.
walls=utils.
wallIds=
sp=pack.
sp.makeCloud(
O.bodies.
Gl1_Sphere.
# Blocked certain degress of freedom to make 2D-Model in plane-XY
for i in O.bodies:
if isinstance(i.shape, Sphere): i.state.
O.dt=.5*
O.usesTimeStepp
triax=TriaxialS
maxMultipli
finalMaxMul
thickness = 0,
stressMask = 3,
internalCom
)
newton=
unb=unbalancedF
O.engines=[
ForceResetter(),
InsertionSortC
InteractionLoop(
[Ig2_
[Ip2_
[Law2_
),
GlobalStiffnes
triax,
TriaxialStateR
newton,
]
triax.goal1=
triax.goal3=0
triax.wall_
triax.wall_
Gl1_Sphere.
yade.qt.
while 1:
O.run(1000, True)
unb=unbalance
print 'unbalanced force:',unb,' top:',triax.
if unb<stabilityTh
break
O.save(
print "### Isotropic state saved ###"
Do you have any suggestions?
Thanks
Leonard
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