New question #694982 on Yade:
https://answers.launchpad.net/yade/+question/694982
Hi
Firstly, A RVE (goal stress-strain
stress(0,0)=0,strain(1,1)=-0.008,stress(0,1)=0, strain(2,:)=0) is calibrated
using the following commands:
-----------------------------------------------
#!/usr/bin/python # This is server.py file
import string
from yade import plot,qt
from yade.pack import *
from yade import pack
O.materials.append(CpmMat(damLaw=0,young=150e9,density=4800,frictionAngle=atan(0.8),poisson=0.4,sigmaT=20e8,epsCrackOnset=0.8e-4,relDuctility=300))
initSize=0.028
sp=pack.randomPeriPack(radius=.000625,initSize=Vector3(initSize,initSize,initSize))
O.periodic=True
sp.toSimulation()
O.save('model.gz')
O.dt=1e-7
def plotAddData():
with open('stressStrain.txt','a') as f:
f.write(str(p3d.strain[0])+' '+str(p3d.strain[1])+ ' ' +
str(p3d.strain[5])+' '+str(p3d.stress[0])+' '+str(p3d.stress[1])+ ' ' +
str(p3d.stress[5]))
f.write('\n')
EnlargeFactor=1.5
EnlargeFactor=1.0
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=EnlargeFactor,label='bo1s')]),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom(interactionDetectionFactor=EnlargeFactor,label='ig2ss')],
[Ip2_CpmMat_CpmMat_CpmPhys()],[Law2_ScGeom_CpmPhys_Cpm()]),
NewtonIntegrator(),
Peri3dController(
nSteps=10000,
# how many time steps the simulation will last
# after reaching nSteps
do doneHook action
doneHook='print
"Simulation with Peri3dController finished."; O.pause()',
label='p3d'
),
PyRunner(command='plotAddData()',iterPeriod=1),
]
p3d.stressMask=0b100001 # prescribed sx,ey,sz,syz,ezx,sxy; e..strain;
s..stress
p3d.goal=(0,-0.008,0,0,0,0) #xx, yy, zz, yz, zx, xy
O.step()
bo1s.aabbEnlargeFactor=ig2ss.interactionDetectionFactor=1.
O.run(); O.wait()
------------------------------------------------------
As you can see, the strain and stress at each step are written in the file
"stressStrain.txt".
Now I want to use the strain in the "stressStrain.txt" to calculate the stress
again using the following commands:
-----------------------------------------------------
#!/usr/bin/python # This is server.py file
import string
from yade.pack import *
from yade import pack
import numpy as np # initial the math of matrix compute (needed in
ns)
# initial the global , variables
arrcc =[0]*3 # last step strain(commit)
arrtt =[0]*3 # last step strain(trail)
scc=[0]*3 # last step stress
orst=1 # initialize the orginal save document(trial)
check=[0]*1 # I need to calculate the first step when ag=0
check[0]=0
pertstrain=[0]*3
count=[0]
# load the identical package
O.load('./model.gz') # only load the package, because the O.cell.velGrad is
not compatible with the peri3dcontroller eigine
#O.periodic=True ### note!!! add
O.dt=1e-8
ns=100
# see the example of peri3dcontroller, 1.5 is used to speed up the computation
EnlargeFactor=1.5
EnlargeFactor=1.0
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=EnlargeFactor,label='bo1s')],allowBiggerThanPeriod=True),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom(interactionDetectionFactor=EnlargeFactor,label='ig2ss')],
[Ip2_CpmMat_CpmMat_CpmPhys()],[Law2_ScGeom_CpmPhys_Cpm()]),
NewtonIntegrator(),
]
O.cell.velGrad=utils.Matrix3(0,0,0,0,0,0,0,0,0)
#O.step()
O.run(1,True)
bo1s.aabbEnlargeFactor=ig2ss.interactionDetectionFactor=1. #
O.step and change 1.5 back to 1. , because the concrete model is developed in
the 1. environment
def response(msg):
# change the form of message
aa = msg.split(',')
global arrcc
global arrtt
global scc
global orst
arr=[0]*3 # change form, the current strain
if orst == 2:
O.loadTmp('temp')
orst == 2
for i in range(0,3):
arr[i] = string.atof(aa[i])
ag = [0]*3 # current - last ie. the changed strain
ag[0] = arr[0] - arrcc[0]
ag[1] = arr[1] - arrcc[1]
ag[2] = (arr[2] - arrcc[2]) # incremental strain
arrcc[0]=arr[0] # update strain
arrcc[1]=arr[1]
arrcc[2]=arr[2]
dstrain = utils.Matrix3(ag[0],ag[2],0,ag[2],ag[1],0,0,0,0) # the
goal strain xx xy xz, yx yy yz, zx zy zz
O.cell.velGrad=dstrain/(ns*O.dt)
O.run(ns,True)
stressValue=utils.getStress()
stressxx=stressValue[0,0] # the
return stress xx
stressyy=stressValue[1,1] # the
return stress yy
stressxy=(stressValue[0,1]+stressValue[1,0])/2 # the
return stress xy = (xy + yx)/2
print stressxx,stressyy,stressxy
O.saveTmp('temp') # different gauss point has different
number(first first ...)
with open('stressStrain.txt','r') as f:
lines=f.readlines()
flen=len(lines)
for i in lines:
numbers=i.split()
strain=map(float,numbers)
msg = str(strain[0])+","+str(strain[1])+","+str(strain[2])
response(msg)
--------------------------------------------------------------------------------------------------------
I thought the stress calculated are the same ones in the "stressStrain.txt"
(or acceptable small errors ), however, they are not, and the results are
seriously affected by the time step O.dt.
I think using the command "O.cell.velGrad=dstrain/(ns*O.dt) "can reach the
strain I want.
Can you please tell me how to solve the problem? my goal is: when I give a
strain, the RVE returns a correct stress (i.e., the one in the stressStrain.txt
)
I would greatly appreciate it if you can help me!
Thank you!
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