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"""
This exemple originated from a discussion in yade-dev/answers on Gitlab [1].
It shows how to create cohesive bonds between distant particles when the initial configuration
is assumed force-free.
[1] https://gitlab.com/yade-dev/answers/-/issues/4022
"""
from yade import pack, plot
import math
#Define materials
cohMat = CohFrictMat(young=1e7, poisson=0.3, frictionAngle=radians(30), density=2600, isCohesive=True, normalCohesion=1e5, shearCohesion=1e5)
#Create spheres
rad = 0.05
#desiredEquilibriumDistance = 0.02 #Desired equilibrium distance between sphere centers
initialSeparation = 0.01 # Initial separation beyond equilibrium
s1 = sphere([0, 0, 0], radius=rad, material=cohMat, fixed=True)
s2 = sphere([2 * rad + initialSeparation, 0, 0], radius=rad, material=cohMat)
s3 = sphere([3.5 * rad + 2 * initialSeparation, 0, 0], radius=0.5 * rad, material=cohMat)
#Add initial velocity to s2
s2.state.vel = Vector3(0.1, 0, 0) # 0.1 m/s in positive x direction
#Add spheres to the scene
O.bodies.append((s1, s2, s3))
#Define engines
O.engines = [
ForceResetter(),
#we enlarge detection distance for the collider to detect all neighbors within a certain range
#it is later reverted for performance reasons.
InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=1.5)], label="collider"),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom6D(interactionDetectionFactor=1.5, label="ig2")],
[Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=False, setCohesionOnNewContacts=False, label="physFunctor")],
[Law2_ScGeom6D_CohFrictPhys_CohesionMoment()]
),
NewtonIntegrator(damping=0),
PyRunner(command='addPlotData()', iterPeriod=1)
]
#Function to add plot data
def addPlotData():
plot.addData(n=O.iter, fn=O.forces.f(0)[0], un=s2.state.pos[0] - s1.state.pos[0] - 2 * rad)
#Set up plot
plot.plots = {'n': ('fn', None, 'un')}
plot.plot()
#Set time step
O.dt = 5e-5
#detect all interactions within 1.5 radius distance
collider.__call__()
#loop over the interactions found by collider
#they are all virtual, so we need "all()" to see them iterable
for i in O.interactions.all():
#you may want additional conditions here depending on the use case
if (True):
i = createInteraction(i.id1, i.id2) # now it is real, not virtual
physFunctor.setCohesion(i, cohesive=True, resetDisp=True)
## Run simulation
#No need to detect distant neighbors any more, the collider will be faster like this
collider.aabbEnlargeFactor = 1
ig2.interactionDetectionFactor = 1
O.run(2000, True)
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