Question #685596 on Yade changed:
https://answers.launchpad.net/yade/+question/685596
Status: Answered => Open
Justin is still having a problem:
Klaus,
I updated the code to be a MWE.
Items to note:
I increased the thickness for the pFacets
I could not recreate the problem with one or even two grass strands. I used 4,
and had the once sphere far in the center-ish of the four. This recreates the
problem every time.
My thoughts, since half the sphere is in the grass strand when the grass
is release, it is simply causing too much force? Thoughts? Or would that
not be an issue.
Thanks,
Justin
from yade.gridpfacet import *
import numpy as np
from yade import utils
from yade import ymport
import sys,time,math,random
from yade import qt
qt.View()
boxCenter = (0,0,.025)
boxDem = (.07,.07,.025) ###
O.materials.append(FrictMat(young=200e9,density=8050,poisson=.3,
label='steel')) # used steel properties to make rigid
blen = boxDem[0]*2 ## Length of Ball pit
bhei = .025 ## Height of Ball pit
# Spheres information
sphereRadius = .004 # [m]
nu = .48
den_rub = 89724 # [kg/m^3]
yng_rub = 3000000 # [Pa]
fric_rub = radians(38) # [degrees]
O.materials.append(FrictMat(frictionAngle=fric_rub,young=yng_rub,density=den_rub,poisson=nu,label='rubber'))
#### SPHERES
phi=20.
E=3.*1e8
O.materials.append( FrictMat(
young=E,poisson=0.5,density=260050,frictionAngle=radians(phi),label='frictMat'
) )
O.bodies.append(
sphere(center=(Vector3(-0.0015,-0.0015-.04,0.05)),radius=sphereRadius,material='frictMat',fixed=False)
)
## Time step set to 20% of Rayleigh Wave
O.dt=.2*utils.RayleighWaveTimeStep() # 0.0011302534626965682
### Steps needed to run sim
sphereFalls = 20000 ### Steps spheres need
to fall and level out and turn on studs
O.engines=[
###Reset all forces stored in Scene::forces (O.forces in
python). Typically, this is the first engine to be run at every step.
In addition, reset those energies that should be reset, if energy tracing is
enabled.
## Resets forces and moments that act on bodies
ForceResetter(),
## Using bounding boxes find possible body collisions.
InsertionSortCollider([
Bo1_Facet_Aabb(),
Bo1_Sphere_Aabb(),
Bo1_GridConnection_Aabb(),
Bo1_PFacet_Aabb(),
]),
InteractionLoop([
Ig2_Facet_Sphere_ScGeom(),
Ig2_Wall_PFacet_ScGeom(),
Ig2_Wall_Sphere_ScGeom(),
Ig2_Sphere_Sphere_ScGeom(),
Ig2_Sphere_GridConnection_ScGridCoGeom(),
Ig2_Sphere_PFacet_ScGridCoGeom(),
Ig2_GridNode_GridNode_GridNodeGeom6D(),
Ig2_GridConnection_GridConnection_GridCoGridCoGeom(),
Ig2_GridConnection_PFacet_ScGeom(),
Ig2_PFacet_PFacet_ScGeom(),
],
[
Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=True,setCohesionOnNewContacts=True),
# internal cylinder physic
Ip2_FrictMat_FrictMat_FrictPhys() # physics for
external interactions, i.e., cylinder-cylinder, sphere-sphere, cylinder-sphere
],
[
Law2_ScGeom_FrictPhys_CundallStrack(), #
contact law for sphere-sphere
Law2_ScGridCoGeom_FrictPhys_CundallStrack(), #
contact law for cylinder-sphere
Law2_ScGeom6D_CohFrictPhys_CohesionMoment(), #
contact law for "internal" cylinder forces
Law2_GridCoGridCoGeom_FrictPhys_CundallStrack(), #
contact law for cylinder-cylinder interaction
]),
NewtonIntegrator(damping=.2,gravity=[0,0,-9.81], label='newtonInt'),
PyRunner(command='turnongrass()',firstIterRun=sphereFalls, nDo=6,
dead=False, label='freeGrass'),
]
## Grass Information
O.materials.append(CohFrictMat(young=100,poisson=0.3,density=40,frictionAngle=np.radians(30),normalCohesion=1e5,shearCohesion=1e5,momentRotationLaw=True,label='grass'))
rCyl = 0.0026 ## Grass was about 1.2 [mm] wide
nL = 4 ## No exact Number here, just trial and error
L = bhei ## Height of spheres
### Grass Creation
### Create all nodes first :
nodesIds=[]
idxc = -1
x_gap = 0.006
y_gap = 0.006
range_x = 2 ## finding the range for x
range_y = 2 ## finding the range for z
cen_y = -(range_y/2)*y_gap ## Allows the "box" of grass to be center in Z
for ii in range(0,range_y):
cen_x = -(range_x/2)*x_gap # Allows the "box" of grass to be center in X
for jj in range(0,range_x):
for z in np.linspace(0,L,nL):
nodesIds.append(O.bodies.append(gridNode([cen_x,cen_y-.04,z+sphereRadius+.004],rCyl,wire=False,fixed=False,material='grass')))
idxc += 1
d = idxc*nL ## Start of grass fiber
cen_x += x_gap
#### Now create connection between the nodes
for k,j in zip(nodesIds[d:d+nL-1],nodesIds[d+1:nodesIds[-1]+1]):
O.bodies.append(gridConnection(k,j,rCyl))
cen_y += y_gap
for kk in range(0,len(nodesIds)): ## First Blocking all DOF's until balls
fall around.
O.bodies[nodesIds[kk]].state.blockedDOFs='xyzXYZ'
def turnongrass():
print("Turning on Grass")
for kk in range(0,len(nodesIds)):
O.bodies[nodesIds[kk]].state.blockedDOFs='' ## Unblocking
all DOF's
for kk in range(0,len(nodesIds),nL):
O.bodies[nodesIds[kk]].state.blockedDOFs='xyzXYZ' ## Blocking
DOF's for Bottom nodes
O.bodies[nodesIds[kk+nL-1]].state.blockedDOFs='' ## Top of
Grass
freeGrass.dead = True
color=[255./255.,102./255.,0./255.]
steel_r = .005
box = []
box.append(O.bodies.append(
gridNode([-boxDem[0],-boxDem[1],0],steel_r,wire=False,fixed=True,material='steel',color=color)
))
box.append(O.bodies.append(
gridNode([boxDem[0],-boxDem[1],0],steel_r,wire=False,fixed=True,material='steel',color=color)
))
box.append(O.bodies.append(
gridNode([boxDem[0],boxDem[1],0],steel_r,wire=False,fixed=True,material='steel',color=color)
))
O.bodies.append( gridConnection(box[0],box[1],steel_r,color=color) )
O.bodies.append( gridConnection(box[1],box[2],steel_r,color=color) )
O.bodies.append( gridConnection(box[2],box[0],steel_r,color=color) )
O.bodies.append(
pfacet(box[0],box[1],box[2],wire=False,color=color,material='steel') )
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