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[Justin <question685596@xxxxxxxxxxxxxxxxxxxxx>]

Question #685596 on Yade changed:
https://answers.launchpad.net/yade/+question/685596

Description changed to:
I seem to get a Segmentation fault (core dumped) when using
GridConnection, PFacet, and randomDensePack. And I am not sure why. I
have attached an image and "working" example.


Thanks in advance,
Justin


Edit: I could not seem to upload an picture or example code. Thus code below:

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()

#print(os.path.basename(__file__))
#quit()
########### ParallelEngine, -j4

boxCenter = (0,0,.025)
## double check that /2 would create correct length, I.e., import based_70 to see if they match... they should
boxDem = (.2123/2,.212/2,.064/2)  ### based_70 is 212.3x212.21x63.65

boxDem = (.07,.07,.025)  ###

blen = boxDem[0]*2  ## Length of Ball pit
bhei = .025       ## Height of Ball pit

# Spheres information
sphereRadius = .004 # [m]
nu = .48 
#G = 300000 # [Pa]
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'))
O.materials.append(FrictMat(young=200e9,density=8050,poisson=.3, label='steel')) # used steel properties to make rigid

## Stud informtion
#studStartZ = (.01+.022+.01905)
studStartZ = (.01+bhei+.01905)
transVel = 0.000222*2
rotVel = 0.00872665*2

### pack auto fills, i.e., I no longer pick the amount of spheres
pred = pack.inAlignedBox((-(boxDem[0]-.001),-(boxDem[0]-.001),bhei+sphereRadius/2+.001),((boxDem[0]-.001),(boxDem[0]-.001),bhei+.045))
sp = pack.randomDensePack(pred, radius=sphereRadius, memoizeDb='tmp/single_grass.sqlite', returnSpherePack=True)
sp.toSimulation(wire=False,material='rubber')

## Time step set to 20% of Rayleigh Wave
O.dt=.2*utils.RayleighWaveTimeStep() # 0.0011302534626965682
print(O.dt)

### Steps needed to run sim
sphereFalls = 1000   														### Steps spheres need to fall and level out and turn on studs
startRot = sphereFalls+math.floor((studStartZ-bhei-.01)/transVel/O.dt)		### Step needed for transVel to get studs level with spheres

## Rotation steps
deg_to_rad_length = (60*pi/180); # [rad]
num_sec_roto = deg_to_rad_length/rotVel; # [s]
num_of_steps_roto = num_sec_roto/O.dt;

endSim   = startRot     + math.floor(num_of_steps_roto)
### total steps in sim

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_PFacet_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 physics
			Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=True),	# internal cylinder physics
			## Currently grass does not interact with facet, probably should not matter, since the spheres will be holding them up.			
				
			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'),
]


## Grass Information
#O.materials.append(CohFrictMat(young=8e5,poisson=0.3,density=4e3,frictionAngle=np.radians(30),normalCohesion=1e5,shearCohesion=1e5,momentRotationLaw=True,label='grass')) ## Properties Need to be corrected
O.materials.append(CohFrictMat(young=100,poisson=0.3,density=40,frictionAngle=np.radians(30),normalCohesion=1e5,shearCohesion=1e5,momentRotationLaw=True,label='grass'))
#rCyl = 0.0006  ## Radius, Grass was about 1.2 [mm] wide
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 = 0.009 ## Between lumps is roughly 9 [mm]
y_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_y = int(math.floor(blen/y_gap)) ## finding the range for z
cen_y = -(range_y/2)*y_gap  ## Allows the "box" of grass to be center in Z

color=[255./255.,102./255.,0./255.]
steel_r = (1/4*0.00635)/2   				### Converting 1/4 steel to m, to a sphere radius
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) ))
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,material='steel') )
O.bodies.append( gridConnection(box[1],box[2],steel_r,color=color,material='steel') )
O.bodies.append( gridConnection(box[2],box[0],steel_r,color=color,material='steel') )
O.bodies.append( gridConnection(box[2],box[3],steel_r,color=color,material='steel') )
O.bodies.append( gridConnection(box[3],box[0],steel_r,color=color,material='steel') )
O.bodies.append( pfacet(box[0],box[1],box[2],wire=False,material='steel',color=color) )
O.bodies.append( pfacet(box[0],box[2],box[3],wire=False,material='steel',color=color) )

O.stopAtIter=endSim   ### Stop sim at endSim steps
#O.run()

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