how to control the wall level when the program is running

Hi, I am studying ‘soil structure interaction’ and meeting some questions again.

I have two scripts and they should run in sequence.

The first script is used to generate particles. The particles expand until the wallstress reach 90kPa.

The second script will load the result of the first script. I delete all the walls of the model and four walls were recreated. The front and back walls aren’t recreated and I don’t know if it is correct. All walls are fixed except the top one. I apply force (100kPa) on the top wall. The top wall may slope (such as right higher than left) when add the force. How do I control it to stay level the whole time when the program is running?

The version of ubuntu is 21.10

The first script:

#########################################
### Defining parameters and variables ###
#########################################

#Material constants
Density = 3000
FrictionAngle = 1.5
PoissonRatio = 0.5
Young = 300e6
Damp = 0.5
N_particles = 4000

#Wall constants
WDensity = 0
WFrictionAngle = 0.0
WPoissonRatio = 0.5
WYoung = 50e9

#Packing variables
mn = Vector3(1,0,0)
mx = Vector3(101,20,1)

#Confining variables
ConfPress1 = -90000 #pre-compression
ConfPress = -1.0e5

#time calculation
startT = O.time
endT = O.time
timeSpent = endT - startT

########################################
#import necessary packages
import matplotlib; matplotlib.rc('axes',grid=True)
import pylab

########################################
### Sample Preparing ###################
########################################

#Create materials for spheres and plates
SphereMat = O.materials.append(FrictMat(young = Young, poisson = PoissonRatio, frictionAngle = radians(FrictionAngle), density = Density))
WallMat = O.materials.append(FrictMat(young = WYoung, poisson = WPoissonRatio, frictionAngle = radians(WFrictionAngle), density = WDensity))

#Create walls for packing
wallIds = O.bodies.append(aabbWalls([mn,mx],thickness=0.001,material=WallMat))

sp = pack.SpherePack()

sp.toSimulation(material = SphereMat)

O.usesTimeStepper=True
O.trackEnerty=True
#################################
#####Defining triaxil engines####
#################################

###first step: compression#######
triax1=TriaxialStressController(
wall_back_activated = False, #for 2d simulation
wall_front_activated = False,
thickness = 0.001,
maxMultiplier=1.+1.5e5/Young, # spheres growing factor (fast growth)
finalMaxMultiplier=1.+4e3/Young,
internalCompaction = True, # If true the confining pressure is generated by growing particles
computeStressStrainInterval = 10,

goal1 = ConfPress1,
goal2 = ConfPress1,
)

newton=NewtonIntegrator(damping=Damp)

###engine
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()]
),
GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8, defaultDt=4*utils.PWaveTimeStep()),
triax1,
newton,
PyRunner(realPeriod=10,command='checkUnbalanced()',label='check'),
]
# Simulation stop conditions defination
def checkUnbalanced():
unb=unbalancedForce()
if unb<0.001:
O.pause()

the second script:

#Wall constants
WDensity = 0
WFrictionAngle = 0.0
WPoissonRatio = 0.5
WYoung = 50e9
Mat = O.materials.append(FrictMat(young = WYoung, poisson = WPoissonRatio, frictionAngle = radians(WFrictionAngle), density = WDensity))
FrictionAngle = 35

Damp = 0.25

#Confining variables
force = -10.0e7 #force=-100000*area(top wall)

#time calculation
startT = O.time
endT = O.time
timeSpent = endT - startT

#restart

########################################
#import necessary packages

for b in range(6):
O.bodies.erase(b)

id_box1 = O.bodies.append(box((0.5,12.5,0.5),(0.5,12.5,0.5),fixed=True,material=Mat))# left wall
id_box2 = O.bodies.append(box((101.5,12.5,0.5),(0.5,12.5,0.5),fixed=True,material=Mat))# right wall
id_box3 = O.bodies.append(box((51,20.5,0.5),(50,0.5,0.5),fixed=False,material=Mat))# top wall
id_box4 = O.bodies.append(box((51,-0.5,0.5),(70,0.5,0.5),fixed=True,material=Mat))# bottom wall

for b in O.bodies:
if isinstance(b.shape,Sphere):
b.shape.color=(0.,0.,1.)

O.forces.setPermF(O.bodies[-2].id,(0,force,0))

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()]
),
GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8, defaultDt=4*utils.PWaveTimeStep()),
NewtonIntegrator(damping=Damp),
PyRunner(realPeriod=2,command='endCheck()',label='check')
]

# Simulation stop conditions defination
def endCheck():
unb=unbalancedForce()
if unb<0.0001:
if O.iter<60000:
return
else:
O.pause()
print('bottom force:',O.forces.f(O.bodies[-1].id))
print('top force:',O.forces.f(O.bodies[-2].id))
print('right force',O.forces.f(O.bodies[-3].id))
print('left force',O.forces.f(O.bodies[-4].id))

Hope anyone can help with my question.
Thanks
Xujin

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Jan Stránský
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Last query:
 Revision history for this message Jan Stránský (honzik) said on 2022-03-24: #1

Hello,

thanks for following the instructions and focusing on one topic per question :-)
The point is that this problem is "fundamental" and it would be pity if it was lost among other unrelated topics..

> How do I control it to stay level the whole time when the program is running?
> id_box3 = O.bodies.append(box(...,fixed=False,...))# top wall

if you do not fix the body (fixed=False), it is free to move and rotate.
You can restrict a free body with state.blockedDOFs [1,2] (as already proposed in [3]).
For example, to block rotations along x and y, you do
###
topWall = O.bodies[id_box3]
topWall.state.blockedDOFs = "XY"
###
This way, the wall can still rotate along z axis and move along all three axes.

Depending on your needs, you can do e.g.
topWall.state.blockedDOFs = "xyXYZ"
which blocks rotation along all three axes (blocking rotation entirely) and blocking translation in x and y directions.
Therefore, only motion in z direction is "free" (determined by external forces and interactions).

> The version of ubuntu is 21.10

usually the Yade version is more important than Ubuntu version

Cheers
Jan

 Revision history for this message William (qfxx-123) said on 2022-03-24: #2

Thanks Jan Stránský, that solved my question.