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[Jan Stránský <question295486@xxxxxxxxxxxxxxxxxxxxx>]

Question #295486 on Yade changed:
https://answers.launchpad.net/yade/+question/295486

Jan Stránský proposed the following answer:
Hello,
this model is designed such that on interaction level it has damage in
tension and plasticity in shear. To have plasticity on macro-level, you
have to adjust parameters somehow (e.g. decrease sigmaT)
As a sidenote, periodicity is not a very good idea for inelastic range in
compression, because the failure mode is not periodic
cheers
Jan


2016-06-20 12:51 GMT+02:00 liukeqi <question295486@xxxxxxxxxxxxxxxxxxxxx>:

> New question #295486 on Yade:
> https://answers.launchpad.net/yade/+question/295486
>
> Hello everyone,
> I want to use the concrete material to simulate the hysteretic curve by
> loading and unloading in turns. I used the periodic boundary and controlled
> the strain. It should have plastic strain when it entered plastic state,
> but I found that no matter how large the strain is when I loaded, it always
> then returned to zero when I unloaded by making the stress to zero. And if
> I wanted to make the stress to zero when I unload by controlling the
> stress, I had to make the strain being zero. I cannot find the concrete
> damage. Can you give me some suggestions? Thanks a lot. This is my code.
> ############################################################
> #!/usr/bin/python           # This is server.py file
> import string
> from yade import plot,qt
> from yade.pack import *
> from yade import pack, plot
>
>
>
> O.materials.append(CpmMat(young=25e9,frictionAngle=.7,poisson=.2,sigmaT=3e6,epsCrackOnset=1e-4,relDuctility=30))
>
> initSize=1.2
>
>
> sp=pack.randomPeriPack(radius=.05,initSize=Vector3(initSize,initSize,initSize))
>
> sp.toSimulation()
>
>
>
>
> O.dt=PWaveTimeStep()/2
>
> plot.plots={'ex':('sx',)}
> def plotAddData():
>         plot.addData(
>                 sx=p3d.stress[0],
>                 ex=p3d.strain[0],
>
>         )
>
> 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=4000,
>               # how many time steps the simulation will last
>                                                         # after reaching
> nSteps do doneHook action
>                                                         doneHook='print
> "Simulation with Peri3dController finished."; O.pause()',
>
>                                                         # the prescribed
> path (step,value of stress/strain) can be defined in absolute values
>
>                                                         # or in relative
> values
>
>                                                         # if the goal
> value is 0, the absolute stress/strain values are always considered (step
> values remain relative)plot.plots={'ex':('sx',)}
>
>                                                         # if ##Path is not
> explicitly defined, it is considered as linear function between (0,0) and
> (nSteps,goal)
>                                                         # as in yzPath and
> xyPath
>                                                         # the relative
> values are really relative (zxPath gives the same - except of the sign from
> goal value - result as yyPath)
>
>
>                                                         # variables used
> in the first step
>                                                         label='p3d'
>                                                         ),
>         PyRunner(command='plotAddData()',iterPeriod=1),
> ]
>
> p3d.stressMask=0b111110       # prescribed ex,ey,sz,syz,ezx,sxy;
>  e..strain;  s..stress
> p3d.goal=(-0.001,0,0,0,0,0)  #xx, yy, zz, yz, zx, xy
> O.step()
> bo1s.aabbEnlargeFactor=ig2ss.interactionDetectionFactor=1.
> O.run(); O.wait()
>
>
> O.engines=[
>         ForceResetter(),
>
> InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=1.,label='bo1s')]),
>         InteractionLoop(
>
> [Ig2_Sphere_Sphere_ScGeom(interactionDetectionFactor=1.,label='ig2ss')],
>                 [Ip2_CpmMat_CpmMat_CpmPhys()],[Law2_ScGeom_CpmPhys_Cpm()]),
>         NewtonIntegrator(),
>         Peri3dController(
>
>                                                         nSteps=4000,
>               # how many time steps the simulation will last
>                                                         # after reaching
> nSteps do doneHook action
>                                                         doneHook='print
> "Simulation with Peri3dController finished."; O.pause()',
>
>                                                         # the prescribed
> path (step,value of stress/strain) can be defined in absolute values
>
>                                                         # or in relative
> values
>
>                                                         # if the goal
> value is 0, the absolute stress/strain values are always considered (step
> values remain relative)plot.plots={'ex':('sx',)}
>
>                                                         # if ##Path is not
> explicitly defined, it is considered as linear function between (0,0) and
> (nSteps,goal)
>                                                         # as in yzPath and
> xyPath
>                                                         # the relative
> values are really relative (zxPath gives the same - except of the sign from
> goal value - result as yyPath)
>
>
>                                                         # variables used
> in the first step
>                                                         label='p3d',
>                                                         strain=p3d.strain
>                                                         ),
>         PyRunner(command='plotAddData()',iterPeriod=1),
> ]
>
> p3d.stressMask=0b111110       # prescribed ex,ey,sz,syz,ezx,sxy;
>  e..strain;  s..stress
> p3d.goal=(0.001,0,0,0,0,0)  #xx, yy, zz, yz, zx, xy
> O.run(); O.wait()
>
>
> plot.plot(subPlots=False)
>
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