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[Nima Goudarzi <question652968@xxxxxxxxxxxxxxxxxxxxx>]

Question #652968 on Yade changed:
https://answers.launchpad.net/yade/+question/652968

Nima Goudarzi gave more information on the question:
 Excuse me Bruno. Attached please find the script. The last one (in the email) is not readable I think.
Sincerely yours,
Nima    On Tuesday, October 17, 2017, 5:10:16 PM CDT, Nima Goudarzi <question652968@xxxxxxxxxxxxxxxxxxxxx> wrote:  
 
 Your question #652968 on Yade changed:
https://answers.launchpad.net/yade/+question/652968

    Status: Answered => Open

You are still having a problem:
 Dear Bruno,
Thanks so much for all your helps. I finally implemented my model in YADE but got some new problems in modelling uniaxial compaction in the python script. I am trying to compact a soil sample layer by layer to reach a target void ratio for each layer and finally a target void ratio for the whole assembly. Worthy to say that, I'll have two distinct scripts. One for uniaxial compaction and one for triaxial test that is to say that I'll export final positions of spheres (after compaction) to my triaxial script. I am familiar with triaxStressController but prefer not to use it since I don't want to use the lubrication concept and expanding the particle size (or shrinking the walls). My final test is a trixal test but I prefer to use a very simple method for compacting using a plate from top of each layer. I mean, I want to use a facetBox as a mold and a simple plate. I have modeled the gravity deposition of the first layer and also put the plate on top of the layer and applied some constant velocity in z direction for moving the plate. Everything goes well but I have a problem with stopping the plate when the porosity of the layer reaches my target porosity. I got some hints from some YADE users regarding this to for checking the voxelPorosity  against my target porosity to stop the plate. Here are my questions:
1- I don't know how I can check the updating porosity against my target porosity since the volume of my layer is changing due to the compaction and as far as I know, voxelPorosity needs a height vector (let's say mx) which in my case is not constant and is gradually deceasing. Is there a way to stop the plate with target porosity in my case or I am enforced to use triaxStressController? 
2- My parameters are updating from compaction to triaxial (due to numerical reasons). One of the reasons I prefer to use two scripts is this. Actually, I don't know if there is an approach to update material parameters in one single script. Please give me some hints if there is a solution.

Here is a draft of my script for compacting the first layer. It doesn't work from yade.pack import *from yade import utilsfrom yade import exportfrom yade import plotn_s = 2000n_band = 26# For now I'm using Sobieski's PSD. I need to change it to my own PSD latertargetPorosity= 0.422##################################################   Particle Size Distribution   ##################################################psdSizes=[5.8598400e+00,5.8761600e+00,5.8924800e+00,5.9088000e+00,5.9251200e+00,5.9414400e+00,5.9577600e+00,5.9740800e+00,5.9904000e+00,6.0067200e+00,6.0230400e+00,6.0393600e+00,6.0556800e+00,6.0720000e+00,6.0883200e+00,6.1046400e+00,6.1209600e+00,6.1372800e+00,6.1536000e+00,6.1699200e+00,6.1862400e+00,6.2025600e+00,6.2188800e+00,6.2352000e+00,6.2515200e+00,6.2678400e+00]psdCumm=[0.0,8.4945735e-05,3.5804112e-04,1.1512195e-03,3.2324246e-03,8.1658647e-03,1.8731095e-02,3.9172232e-02,7.4902028e-02,1.3132521e-01,2.1182373e-01,3.1558203e-01,4.3640887e-01,5.6352779e-01,6.8435463e-01,7.8811293e-01,8.6861145e-01,9.2503463e-01,9.6076443e-01,9.8120556e-01,9.9177079e-01,9.9670423e-01,9.9878544e-01,9.9957862e-01,9.9985171e-01,1.0]
i = 0while i < n_band:    psdSizes[i]=psdSizes[i]/1000. #scaling from [mm] to [m]    print "\r psdSizes:",i,psdSizes[i]    i = i +1
#If the bed volume is defined, then the average diameter of particles (when the target porosity is reached) is the same like in the measurement###########################################################   facetBox   ############################################################ Compaction will be in Y-Directionl = 3.5e-3h = 7.1e-3vol = l*h*l# You maybe don't need this if you use compaction from the top of the sample (using plate)
mn = Vector3(0,0,0)mx = Vector3(l,l,h/5)
O.materials.append(FrictMat(young=5e6,poisson=0.5,frictionAngle=0,density=0,label='walls'))O.materials.append(FrictMat(young=5e6,poisson=0.5,frictionAngle=radians(30),density=2600,label='spheres'))O.bodies.append(geom.facetBox((l/2,l/2,h/2),(l/2,l/2,h/2),wallMask=31,material='walls'))# This will be an open-top boxsp = yade._packSpheres.SpherePack()sp.makeCloud(mn,mx,psdSizes=psdSizes,psdCumm=psdCumm,num=n_s,distributeMass=1)O.bodies.append([sphere(s[0],s[1],material='spheres') for s in sp])Porosity = voxelPorosity(200,mn,mx)print "\r Porosity: ",Porosity,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=2,label='checker'),]O.dt=.5*PWaveTimeStep()
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,-.1)   # start plotting the data now, it was not interesting before   O.engines=O.engines+[PyRunner(command='addPlotData()',iterPeriod=200)]   # next time, do not call this function anymore, but the next one (unloadPlate) instead   checker.command='unloadPlate()'def unloadPlate():   # if the porosity of the layer goes below the target porosity stop unloading   maxz=max([b.state.pos[2]+b.shape.radius for b in O.bodies if is instance(b.shape,Sphere)])   mx=maxz# Iknow this doesn't work   Por_osity=voxelPorosity(200,mn,mx)   if Por_osity <targetPorosity:      plate.state.vel=(0,0,0)

Thanks so much,
Sincerely yours
Nima    On Monday, July 31, 2017, 7:27:43 AM CDT, Bruno Chareyre <question652968@xxxxxxxxxxxxxxxxxxxxx> wrote:  
 
 Your question #652968 on Yade changed:
https://answers.launchpad.net/yade/+question/652968

    Status: Open => Answered

Bruno Chareyre proposed the following answer:
Hi,
This code you mention is related to viscous contact damping, not Cundall's damping. It appears to be doing nothing if "useDamping" is turned false, so I guess you can do just that and then there is no need to worry about cn, cs.
I mean to set useDamping=False in simulation scripts, there is absolutely nothing to change in the source code as I see it.
Cheers
Bruno

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