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[Luis Barbosa <question248907@xxxxxxxxxxxxxxxxxxxxx>]

New question #248907 on Yade:
https://answers.launchpad.net/yade/+question/248907

Hi,
I'm studying some contact law, for this reason I have compared:

#First Facet with cohesion to simulate the adhesion between particle and face:

#exercicio de plotagem com 02 esferas com leis de contato diferentes
# import yade modules that we will use below
from yade import plot
#Definir material
# create rectangular box from facets
#O.materials.append(FrictMat(young=15e6,poisson=.4,frictionAngle=radians(20),density=4000,))
O.materials.append(CohFrictMat(young=15e6,poisson=0.3,density=4000,frictionAngle=radians(20),isCohesive=True,normalCohesion=1e6,shearCohesion=1e6,momentRotationLaw=True,etaRoll=0.1,label='spheres'))
O.bodies.append(utils.geom.facetBox((.5,.5,.5),(.5,.5,.5),wallMask=31))
# Criar a esfera coesiva
O.materials.append(CohFrictMat(young=15e6,poisson=0.3,density=2600,frictionAngle=radians(30),isCohesive=True,normalCohesion=1e10,shearCohesion=1e10,momentRotationLaw=True,etaRoll=0.1,label='spheres'))
O.bodies.append([utils.sphere(center=(0.5,0.5,1),radius=.07)])
O.bodies.append([utils.sphere(center=(0.5,0.6,0.5),radius=.07)])
# Criar interacoes
O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom6D(),Ig2_Facet_Sphere_ScGeom6D()],
#[Ip2_FrictMat_FrictMat_FrictPhys(), 
[Ip2_CohFrictMat_CohFrictMat_CohFrictPhys (setCohesionNow=True,label="cohesiveIp")],
#[Law2_ScGeom_FrictPhys_CundallStrack(),
[Law2_ScGeom6D_CohFrictPhys_CohesionMoment(label='cohesiveLaw')]
),

   GravityEngine(gravity=(0,0,-9.81)),
   NewtonIntegrator(damping=0.4),
   PyRunner(command='myAddData()',iterPeriod=20)

]
O.dt=.5e-1*utils.PWaveTimeStep()

def myAddData():
        b=O.bodies[10]
        plot.addData(z1=b.state.pos[2],v1=b.state.vel.norm(), i=O.iter, t=O.time)

plot.plots={
        't':('z1','v1') # z1(t) and v1(t)
}

plot.plot()
O.saveTmp()

And

#Second Facet without cohesion

#exercicio de plotagem com 02 esferas com leis de contato diferentes
# import yade modules that we will use below
from yade import plot
#Definir material
# create rectangular box from facets
O.materials.append(FrictMat(young=15e6,poisson=.4,frictionAngle=radians(20),density=4000,))
#O.materials.append(CohFrictMat(young=15e6,poisson=0.3,density=4000,frictionAngle=radians(20),isCohesive=True,normalCohesion=1e60,shearCohesion=1e60,momentRotationLaw=True,etaRoll=0.1,label='spheres'))
O.bodies.append(utils.geom.facetBox((.5,.5,.5),(.5,.5,.5),wallMask=31))
# Criar a esfera coesiva
O.materials.append(CohFrictMat(young=15e6,poisson=0.3,density=2600,frictionAngle=radians(30),isCohesive=True,normalCohesion=1e1000,shearCohesion=1e1000,momentRotationLaw=True,etaRoll=0.1,label='spheres'))
O.bodies.append([utils.sphere(center=(0.5,0.5,1),radius=.07)])
O.bodies.append([utils.sphere(center=(0.5,0.6,0.5),radius=.07)])
# Criar interacoes
O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom6D(),Ig2_Facet_Sphere_ScGeom()],
[Ip2_FrictMat_FrictMat_FrictPhys(), 
Ip2_CohFrictMat_CohFrictMat_CohFrictPhys (setCohesionNow=True,label="cohesiveIp")],
[Law2_ScGeom_FrictPhys_CundallStrack(),
Law2_ScGeom6D_CohFrictPhys_CohesionMoment(label='cohesiveLaw')]
),

   GravityEngine(gravity=(0,0,-9.81)),
   NewtonIntegrator(damping=0.4),
   PyRunner(command='myAddData()',iterPeriod=20)

]
O.dt=.5e-1*utils.PWaveTimeStep()

def myAddData():
        b=O.bodies[10]
        plot.addData(z1=b.state.pos[2],v1=b.state.vel.norm(), i=O.iter, t=O.time)

plot.plots={
        't':('z1','v1') # z1(t) and v1(t)
}

plot.plot()

O.saveTmp()


For both the message is;

WARN  /tmp/buildd/yadedaily-1.05.0-28-g5e71fa5~precise/pkg/dem/CohesiveFrictionalContactLaw.cpp:156 go: If :yref:`Law2_ScGeom6D_CohFrictPhys_CohesionMoment::useIncrementalForm` is false, then plasticity will not be applied correctly (the total formulation would not reproduce irreversibility).

1) Are there some consideration wrong
2) Am I right to simulate adhesion by doing a Facet with cohesion, or is not necessary

Thanks

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