Re: [Yade-users] [Question #404135]: intRadius(aabbenlargefactor) doesn't work
Question #404135 on Yade changed: https://answers.launchpad.net/yade/+question/404135 Status: Open => Answered Jérôme Duriez proposed the following answer: 1. The behavior you observed is normal. As the doc of cohesiveTresholdIteration [1] says, Ip2_JCFpmMat_JCFpmMat_JCFpmPhys will set as cohesive only the *new* contacts. In fact, it is a general rule in YADE that any Ip2_* executes his job (which is to define interaction properties) only once, where interactions are created. If you'd like to "apply" cohesion to a previously created packing, you have to perform yourself Ip2_JCFpmMat_JCFpmMat_JCFpmPhys's corresponding job, using Python loops: for interaction in O.interactions: interaction.phys.isCohesive = True # define cohesive thresholds interaction.phys.FnMax [2] and interaction.phys.FsMax [3] from material properties such as done in source code [4]. See also corresponding equations e.g. in [Duriez2016] (listed among the references of the doc) 2. Why are you expecting 13 as a coordination number ? The coordination number you will eventually get for a given interaction radius highly depends on the packing you're considering. There is no unique relationship coordination number = f(interaction radius) [1] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Ip2_JCFpmMat_JCFpmMat_JCFpmPhys.cohesiveTresholdIteration [2] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.JCFpmPhys.FnMax [3 ]https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.JCFpmPhys.FsMax [4] https://github.com/yade/trunk/blob/master/pkg/dem/JointedCohesiveFrictionalPM.cpp#L260 and line below -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #403663]: Modeling 2 materilas by CPM model
Question #403663 on Yade changed:
https://answers.launchpad.net/yade/+question/403663
Status: Answered => Open
Seti is still having a problem:
Hi Jan,
Thanks for your help, , in a sample with just two materials. I have done a
series of parametric studies to understand how changing( say increasing) the
percentage of material #1 has effect on the strength of sample. By increasing
the percentage of mat 1 ( %10, %30, %70) the strength of sample has been
increased respectively. However when I increase the percentage of mat 1 to 90%
I have drop in stress - strain curve ( strength even less that 30 %)
Is there any issue with the script or there is a convergence problem
here?
Thanks so much for your help.
#!/usr/bin/python
# -*- coding: utf-8 -*-
from __future__ import division
from yade import plot,pack,timing
import time, sys, os, copy
#import matplotlib
#matplotlib.rc('text',usetex=True)
#matplotlib.rc('text.latex',preamble=r'\usepackage{concrete}\usepackage{euler}')
"""
A fairly complex script performing uniaxial tension-compression test on
hyperboloid-shaped specimen.
Most parameters of the model (and of the setup) can be read from table using
yade-multi.
After the simulation setup, tension loading is run and stresses are
periodically saved for plotting
as well as checked for getting below the maximum value so far. This indicates
failure (see stopIfDamaged
function). After failure in tension, the original setup is loaded anew and the
sense of loading reversed.
After failure in compression, strain-stress curves are saved via
plot.saveGnuplot and we exit,
giving some useful information like peak stresses in tension/compression.
Running this script for the first time can take long time, as the specimen is
prepared using triaxial
compression. Next time, however, an attempt is made to load
previously-generated packing
(from /tmp/triaxPackCache.sqlite) and this expensive procedure is avoided.
The specimen length can be specified, its diameter is half of the length and
skirt of the hyperboloid is
4/5 of the width.
The particle size is constant and can be specified using the sphereRadius
parameter.
The 3d display has displacement scaling applied, so that the fracture looks
more spectacular. The scale
is 1000 for tension and 100 for compression.
"""
# default parameters or from table
readParamsFromTable(noTableOk=True, # unknownOk=True,
young=30e9,
poisson=.2,
sigmaT=1.1e9,
frictionAngle=atan(.57),
epsCrackOnset=1e-4,
relDuctility=30,
intRadius=1.5,
dtSafety=.8,
damping=0.4,
strainRateTension=.1,
strainRateCompression=.1,
setSpeeds=True,
# 1=tension, 2=compression (ANDed; 3=both)
doModes=2,
specimenLength=.15,
sphereRadius=3.5e-3,
# isotropic confinement (should be negative)
isoPrestress=0,
)
from yade.params.table import *
if 'sigmaT=3.5e6, compression' in O.tags.keys():
O.tags['id']=O.tags['id']+O.tags['sigmaT=3.5e6, compression']
# make geom; the dimensions are hard-coded here; could be in param table if
desired
# z-oriented hyperboloid, length 20cm, diameter 10cm, skirt 8cm
# using spheres 7mm of diameter
mat1=CpmMat(young=young,frictionAngle=atan(.32),poisson=poisson,density=4800,sigmaT=sigmaT,relDuctility=relDuctility,epsCrackOnset=epsCrackOnset,isoPrestress=isoPrestress)
mat2=CpmMat(young=30e9,frictionAngle=frictionAngle,poisson=poisson,density=4800,sigmaT=sigmaT,relDuctility=relDuctility,epsCrackOnset=epsCrackOnset,isoPrestress=isoPrestress)
concreteId1=O.materials.append(CpmMat(young=young,frictionAngle=atan(.32),poisson=poisson,density=4800,sigmaT=sigmaT,relDuctility=relDuctility,epsCrackOnset=epsCrackOnset,isoPrestress=isoPrestress))
concreteId2=O.materials.append(CpmMat(young=young,frictionAngle=frictionAngle,poisson=poisson,density=4800,sigmaT=sigmaT,relDuctility=relDuctility,epsCrackOnset=epsCrackOnset,isoPrestress=isoPrestress))
#sp=pack.randomDensePack(pack.inHyperboloid((0,0,-.5*specimenLength),(0,0,.5*specimenLength),.25*specimenLength,.17*specimenLength),spheresInCell=2000,radius=sphereRadius,memoizeDb='/tmp/triaxPackCache.sqlite',returnSpherePack=True)
#
sp=pack.SpherePack()
pred=pack.inCylinder((0,0,0.002),(0,0,0.3),0.05)
O.bodies.append(pack.randomDensePack(pred,radius=0.008))
#pred=pack.inCylinder((0,0,0),(0,0,0.2),0.1)
#sp=pack.randomDensePack(pred,radius=0.002,material=concreteId)
#O.bodies.append(TS1)
##
#sp=pack.randomDensePack(pack.inAlignedBox((-.25*specimenLength,-.25*specimenLength,-.5*specimenLength),(.25*specimenLength,.25*specimenLength,.5*specimenLength)),spheresInCell=2000,radius=sphereRadius,memoizeDb='/tmp/triaxPackCache.sqlite',returnSpherePack=True)
sp.toSimulation()
for b in O.bodies:
if random.random() < 0.3:
b.mat = mat1
b.shape.color = (1,0,0)
else:
b.mat = mat2
b.shape.color = (0,1,1)
bb=uniaxialTes
Re: [Yade-users] [Question #404228]: the normal force of CmpMat
Question #404228 on Yade changed: https://answers.launchpad.net/yade/+question/404228 Status: Answered => Solved liukeqi confirmed that the question is solved: Thanks Jan Stránský, that solved my question. -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #404228]: the normal force of CmpMat
Question #404228 on Yade changed: https://answers.launchpad.net/yade/+question/404228 Status: Open => Answered Jan Stránský proposed the following answer: Hi Liu, 1) there is a misprint in the thesis, the code is correct, i.e. omega = 1 - (e0/kappa)*exp(-(kappa-e0)/ef) for kappa=e0, damage should be 0 2) ok, this comment is clearly misleading and not true.. It is true for linear damaged stress-strain law. but for default exponential one, epsF controls the slope of the exponential but the exponential is never 0.. cheers Jan -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #404228]: the normal force of CmpMat
Question #404228 on Yade changed: https://answers.launchpad.net/yade/+question/404228 Status: Answered => Open liukeqi is still having a problem: Hello Jan Thanks for your reply. But I still have question. [1]First, the formula to compute the Normal Stresses σN = [1 - ωH(εN)]kNεN in the paper page 38 is same as the formula sigmaN = (1-(epsN-epsNPl>0?omega:0))*E*(epsN-epsNPl) in the source code ConcretePM.cpp. But the formula to compute damage variable ω = g(κ) = 1 -εf/κ*exp(-(κ - ε0)/εf) in the paper page 38 is not same as the formula omega = isCohesive? phys->funcG(kappaD,epsCrackOnset,epsFracture,neverDamage,damLaw) : 1., funcG return 1.-(epsCrackOnset/kappaD)*exp(-(kappaD-epsCrackOnset)/epsFracture) in the source code ConcretePM.cpp. The formula in the source code changed to ω = g(κ) = 1 -ε0/κ*exp(-(κ - ε0)/εf). That is εf change to ε0 in εf/κ. Which is true, paper or source code? [2]According the source code comments, the εf(epsFracture) should be the "strain at which the bond is fully broken". That is, when the tensile strain reach the εf, the stress should be zero, or at least tends to zero. But if I use the formula in paper page or 38 σN = [1 - ωH(εN)]kNεN or the formula in source code sigmaN = (1-(epsN-epsNPl>0?omega:0))*E *(epsN-epsNPl), if I used the same value as papar said that εf is 30ε0 and ε0 is 0.0001, the σN is about 280 when the εN is 30ε0, not zero! Why?Do I have some misunderstandings about it? Thank you. Liu -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #404228]: the normal force of CmpMat
Question #404228 on Yade changed: https://answers.launchpad.net/yade/+question/404228 Status: Open => Answered Jan Stránský proposed the following answer: Hello Liu 1) exactly as you explained. You can use Law2_ScGeom_CpmPhys_Cpm.omegaThreshold [1] to delete the interaction at certain damage level But even if the interaction exists, the normal force tends to zero for larger strains.. 2) rate-dependency means section 3.2.3.2 Vsico-damage and related figure 3.4 cheers Jan [1] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Law2_ScGeom_CpmPhys_Cpm.omegaThreshold -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
