New question #663930 on Yade:
https://answers.launchpad.net/yade/+question/663930
I have a box filled with "grass" using pfacetCreator. The problem is, the
pfacetCreator rapidly expands(does crazy things) after the DOF's are opened up
for the nodes. Why is this happening? I would like the grass to be able to
move, but stay the same length. And constrained at the bottom node only.
Code: (I have a box to keep the balls in, but commented it out, the problem
stills occurs )
from yade.gridpfacet import *
import numpy as np
from yade import utils
from yade import ymport
import sys,time,math,random
# Spheres information
sphereRadius = .004 # [m]
nu = .48
#G = 300000 # [Pa]
den_rub = 24299.1 # [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'))
### Steps
spheres_fall = 200
Trans = 105280+spheres_fall
All_steps = 252510+spheres_fall
blen = 0.21230 ## Length of Ball pit
bhei = .025 ## Height of Ball pit
pred =
pack.inAlignedBox((-blen/2,(0+bhei+.001),-blen/2),(blen/2,(bhei+bhei+.001),blen/2))
sp = pack.randomDensePack(pred, spheresInCell=2732, radius=sphereRadius,
memoizeDb='/home/justin/Desktop/real/tmp/ball_packing65_r4_h25.sqlite',
returnSpherePack=True)
sp.toSimulation(color=(255,0,0),wire=False,material='rubber')
## Steel box informaion
#steel = O.materials.append(FrictMat(young=200e9,density=8050,poisson=.3)) #
Pa, kg/m^3
#metal_base45 =
O.bodies.append(ymport.gmsh("geo/fliped/based_70.mesh",scale=.001,shift=Vector3(0,-.00635,0),
material=steel,color=(0,0,1)))
## Grass Information
O.materials.append(CohFrictMat(young=3e9,density=1150,poisson=.3,frictionAngle=10,normalCohesion=1e7,shearCohesion=1e7,momentRotationLaw=True,label='grass'))
rCyl = 0.0006 ## Grass was about 1.2 [mm] wide
nL = 2 ## No exact Number here, just trial and error
L = .022 ## Height of spheres after leveling
## Time step set to 20% of Rayleigh Wave
#O.dt= 0.000407535525016 #.2*utils.RayleighWaveTimeStep() # 0.000407535525016
O.dt= .2*utils.RayleighWaveTimeStep()
print O.dt
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_Sphere_Aabb(),
Bo1_Facet_Aabb(),
Bo1_PFacet_Aabb(),
]),
InteractionLoop([
Ig2_Facet_Sphere_ScGeom(),
Ig2_Sphere_Sphere_ScGeom(),
Ig2_GridNode_GridNode_GridNodeGeom6D(),
Ig2_Sphere_PFacet_ScGridCoGeom(),
Ig2_PFacet_PFacet_ScGeom(),
],
[
Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=True,setCohesionOnNewContacts=False),
# internal cylinder physics
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,-9.81,0],label='newtonInt'),
PyRunner(command='switchTranslationEngine()',firstIterRun=Trans, nDo =
6, label='switchEng', dead = False),
PyRunner(command='turnongrass()',firstIterRun=spheres_fall, nDo = 3,
dead = False),
]
color=[255./255.,102./255.,0./255.]
### Grass Creation
### Create all nodes first :
nodesIds=[]
nodesIds2=[]
idxc = -1
x_gap = 0.009 ## Between lumps is roughly 9 [mm]
z_gap = 0.01905 ## Between lines of backing is .75 inch apart
range_x = int(math.floor(blen/x_gap)) ## finding the range for x
range_z = int(math.floor(blen/z_gap)) ## finding the range for z
cen_z = -(range_z/2)*z_gap ## Allows the "box" of grass to be center in Z
#sys.exit()
for ii in range(0,range_z):
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 i in np.linspace(0,L,nL):
nodesIds.append(O.bodies.append(gridNode([cen_x,i,cen_z],rCyl,wire=False,fixed=False,material='grass')))
for i in np.linspace(0,L,nL):
nodesIds2.append(O.bodies.append(gridNode([cen_x+.001,i,cen_z],rCyl,wire=False,fixed=False,material='grass')))
idxc += 1
d = idxc*nL ## Start of grass fiber
cen_x += x_gap
cen_z += z_gap
## Creates Nodes Connetions
move_up = 0 ## Moving up to node above
for k in range(0,nL-1):
for i in range(0,len(nodesIds),nL):
pfacetCreator3(nodesIds[i+move_up],nodesIds2[i+move_up],nodesIds2[i+1+move_up],cylIds=[],pfIds=[],wire=False,material='grass',color=color)
for i in range(0,len(nodesIds2),nL):
pfacetCreator3(nodesIds2[i+1+move_up],nodesIds[i+1+move_up],nodesIds[i+move_up],cylIds=[],pfIds=[],wire=False,material='grass',color=color)
move_up += 1
## Creates BC's for all Nodes
for kk in range(0,len(nodesIds)):
O.bodies[nodesIds[kk]].state.blockedDOFs='xyzXYZ'
O.bodies[nodesIds2[kk]].state.blockedDOFs='xyzXYZ'
## Blocking DOF's for top and bottom Nodes
btm_nodes = range(0,len(nodesIds),nL)
top_nodes = range(nL-1,len(nodesIds),nL)
def turnongrass():
print "Turning on Grass"
for kk in range(0,len(nodesIds)):
# if any(x == kk for x in top_nodes) == False: ##
Allows only the top nodes to have ZERO DOF's
if any(xx == kk for xx in btm_nodes) == False: ##
Allows only the bottom nodes to have ZERO DOF's
O.bodies[nodesIds[kk]].state.blockedDOFs='' ##
Unblocking all DOF's - Except Above
O.bodies[nodesIds2[kk]].state.blockedDOFs='' ##
Unblocking all DOF's - Except Above
def run(self):
iterToRun=All_steps
O.run(iterToRun, True)
def switchTranslationEngine():
print "Switch from TranslationEngine engine to RotationEngine"
transeng.dead = True
rotengine.dead = False
# Force Recorders
trans_force.dead = True
rotation_force.dead = False
switchEng.dead = True
from yade import qt
qt.View()
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