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[Panos <question687174@xxxxxxxxxxxxxxxxxxxxx>]

New question #687174 on Yade:
https://answers.launchpad.net/yade/+question/687174

Hello everyone,
I am having trouble plotting the forces, exerted on a facet object (Disk), due to its interaction with synthetic rock (DEM particles). The forces are plotted against distance (dz), with distance being the position of the disk, at every time step during the cutting process.
The thing is that while simulation runs, at some point plotted forces, seem to bounce back, not agreeing with the current disk position (are plotted in the opposite direction).
This only happens, if the facet object rotates and translates at the same time. By setting its angular velocity to zero, it seems to work fine.
What could I do to fix this problem?
Could you take a look in my code? Thanks a lot.

from __future__ import print_function
from __future__ import division
from yade import pack, plot, geom, pack,utils,ymport,export,bodiesHandling
from yade.pack import *
from yade import _packPredicates
import math
from yade import *

################# SIMULATIONS DEFINED HERE
#### Simulation
OUT='LinearCutTest_JCFPM'

#### Material microproperties
readParamsFromTable(noTableOk=True, 
	Sphere_Radius = 2e-3,
	intR=1.1,
	DENSITY=2600, 
	YOUNG=30e9,
	FRICTION_ANGLE=10,
	POISSON=2.5,
	TENS=10e6,
	COH=100e6,
	Z=165.5e-3)

from yade.params.table import *

#### material definition
Sample = O.materials.append(JCFpmMat(
	young=YOUNG, 
	poisson=POISSON, 
	frictionAngle=radians(FRICTION_ANGLE), 
	cohesion=COH, 
	tensileStrength=TENS,
	density = DENSITY,
	label='spheres'
))

#### create the specimen
specimen=pack.randomDensePack(
	pack.inAlignedBox((-0.02735,-0.1097,0.025),(0.02735,-0.055,Z)),
	radius = Sphere_Radius,
	spheresInCell = 1000,
	material=Sample,
	rRelFuzz=0.34,
	memoizeDb = '/tmp/Test.db',
	returnSpherePack = True,
)
specimen.toSimulation()

#### Disk Creation
Disk=geom.facetCylinder(center=(0,0,0),radius=0.06,height=0.01,segmentsNumber=50,wallMask=7,closeGap=True,orientation=Quaternion((0,1,0), pi/2))
O.bodies.append(Disk)
ids = [b.id for b in Disk]


################# ENGINES DEFINED HERE
O.engines=[
 ForceResetter(),
        InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=intR,label='Saabb'),Bo1_Facet_Aabb()],verletDist=.05*Sphere_Radius),
 InteractionLoop(
  [Ig2_Sphere_Sphere_ScGeom(interactionDetectionFactor=intR,label='SSgeom'),Ig2_Facet_Sphere_ScGeom()],
  [Ip2_JCFpmMat_JCFpmMat_JCFpmPhys(cohesiveTresholdIteration=1,label='interactionPhys')],
  [Law2_ScGeom_JCFpmPhys_JointedCohesiveFrictionalPM(recordCracks=True,Key=OUT,label='interactionLaw')]
 ),
 GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=10,timestepSafetyCoefficient=0.5,defaultDt=utils.PWaveTimeStep()),
 NewtonIntegrator(damping=0.5,label='newton'),
 PyRunner(iterPeriod=int(1),initRun=True,command='recorder()',label='data'),
CombinedKinematicEngine(ids=ids,comb=[
 TranslationEngine(translationAxis=[0,0,1],velocity=+500,label="trans"),
 RotationEngine(angularVelocity=60000,rotationAxis=[1,0,0],rotateAroundZero=True,zeroPoint=(0.0,0.0,0.0),label="rot")],label='Eng'),
PyRunner(iterPeriod=1,command="rot.zeroPoint+=(0,0,trans.velocity*O.dt)"),
 PyRunner(iterPeriod=int(1), command='Stop()',label='data')
]
O.dt=.5e-4*PWaveTimeStep()

#################
def recorder():
   global Fz, Fx, Fy
   global dz
   Fz = 0.0
   dz = 0.0
   Fz = abs(sum(O.forces.f(facet.id)[2] for facet in Disk))
   Fx = abs(sum(O.forces.f(facet.id)[0] for facet in Disk))
   Fy = abs(sum(O.forces.f(facet.id)[1] for facet in Disk))
   yade.plot.addData({'i':O.iter,
        'FN':Fy,
        'FR':Fz,
        'dz':(Disk[2].state.pos[2])})
   plot.saveDataTxt(OUT)

def Stop():
    if Disk[2].state.pos[2] >= 190e-3:
        O.pause()

# plot during simulation
plot.plots={'dz':('FR','FN')}
plot.plot()

O.step();
SSgeom.interactionDetectionFactor=-1.
Saabb.aabbEnlargeFactor=-1.

plot.plot()
#O.run()


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