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[Xifan Li <question700872@xxxxxxxxxxxxxxxxxxxxx>]

Question #700872 on Yade changed:
https://answers.launchpad.net/yade/+question/700872

Description changed to:
I want to set the flexible boundary in Yade.

>From the answer https://answers.launchpad.net/yade/+question/254339
I found that there are several options to achieve this. Such as the bonded particles, and the flexible membrane by woo.

But I want to try another way:
[1] finish the same task in Fig.9 as this paper: https://ascelibrary.org/doi/full/10.1061/(ASCE)GM.1943-5622.0001001
[2] In the above paper, the author set the boundary as the bonded particles, But I want to import velocity (stress) on each particle.
[3]Maybe we can try to set the moving rigid boundary so that So we can look at it approximately as a flexible boundary?

I do not know which way is the best and achievable.

Any reply would be a grateful appreciate.

My Yade code is as followed, which was modified from the Oedemetric Test from the Examples, and I do not know how to modify it.
#################################################
# load parameters from file if run in batch
# default values are used if not run from batch
readParamsFromTable(rMean=.03,rRelFuzz=0,maxLoad=1.5e4,minLoad=1e1)
# make rMean, rRelFuzz, maxLoad accessible directly as variables later
from yade.params.table import *

# create box with free top, and ceate loose packing inside the box
from yade import pack, plot
O.bodies.append(geom.facetBox((1,0,1),(1,.03,1),wallMask=31))
#O.bodies.append(geom.facetBox((0,0,0),(.5,.03,.5),wallMask=31))
sp=pack.SpherePack()
sp.makeCloud((0,0,0),(2,0.03,2),rMean=rMean,rRelFuzz=rRelFuzz)
#sp.makeCloud((0,0,0),(-0.5,0.03,-0.25),rMean=rMean,rRelFuzz=rRelFuzz)
sp.toSimulation()

O.engines=[
 ForceResetter(),
 # sphere, facet, wall
 InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb(),Bo1_Wall_Aabb()]),
 InteractionLoop(
  # the loading plate is a wall, we need to handle sphere+sphere, sphere+facet, sphere+wall
  [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom(),Ig2_Wall_Sphere_ScGeom()],
  [Ip2_FrictMat_FrictMat_FrictPhys()],
  [Law2_ScGeom_FrictPhys_CundallStrack()]
 ),
 NewtonIntegrator(gravity=(0,0,-9.81),damping=0.5),
 # the label creates an automatic variable referring to this engine
 # we use it below to change its attributes from the functions called
 PyRunner(command='checkUnbalanced()',realPeriod=1,label='checker'),
]
O.dt=.5*PWaveTimeStep()

# the following checkUnbalanced, unloadPlate and stopUnloading functions are all called by the 'checker'
# (the last engine) one after another; this sequence defines progression of different stages of the
# simulation, as each of the functions, when the condition is satisfied, updates 'checker' to call
# the next function when it is run from within the simulation next time


# check whether the gravity deposition has already finished
# if so, add wall on the top of the packing and start the oedometric test
def checkUnbalanced():
	# at the very start, unbalanced force can be low as there is only few contacts, but it does not mean the packing is stable
	if O.iter < 5000:
		return
	# the rest will be run only if unbalanced is < .1 (stabilized packing)
	if unbalancedForce() > .1:
		return
	# add plate at the position on the top of the packing
	# the maximum finds the z-coordinate of the top of the topmost particle
	O.bodies.append(wall(max([b.state.pos[2] + b.shape.radius for b in O.bodies if isinstance(b.shape, Sphere)]), axis=2, sense=-1))
	global plate  # without this line, the plate variable would only exist inside this function
	plate = O.bodies[-1]  # the last particles is the plate
	# Wall objects are "fixed" by default, i.e. not subject to forces
	# prescribing a velocity will therefore make it move at constant velocity (downwards)
	plate.state.vel = (0, 0, -.05)
	# start plotting the data now, it was not interesting before
	O.engines = O.engines + [PyRunner(command='addPlotData()', iterPeriod=50)]
	# next time, do not call this function anymore, but the next one (unloadPlate) instead
	checker.command = 'unloadPlate()'


def unloadPlate():
	# if the force on plate exceeds maximum load, start unloading
	if abs(O.forces.f(plate.id)[2]) > maxLoad:
		plate.state.vel *= -1
		# next time, do not call this function anymore, but the next one (stopUnloading) instead
		checker.command = 'stopUnloading()'


def stopUnloading():
	if abs(O.forces.f(plate.id)[2]) < minLoad:
		# O.tags can be used to retrieve unique identifiers of the simulation
		# if running in batch, subsequent simulation would overwrite each other's output files otherwise
		# d (or description) is simulation description (composed of parameter values)
		# while the id is composed of time and process number
		plot.saveDataTxt(O.tags['d.id'] + '.txt')
		O.pause()


def addPlotData():
	if not isinstance(O.bodies[-1].shape, Wall):
		plot.addData()
		return
	Fz = O.forces.f(plate.id)[2]
	plot.addData(Fz=Fz, w=plate.state.pos[2] - plate.state.refPos[2], unbalanced=unbalancedForce(), i=O.iter)


# besides unbalanced force evolution, also plot the displacement-force diagram
plot.plots = {'i': ('unbalanced',), 'w': ('Fz',)}
plot.plot()

O.run()
# when running with yade-batch, the script must not finish until the simulation is done fully
# this command will wait for that (has no influence in the non-batch mode)
waitIfBatch()

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