Using CpmMat to simulate the hysteretic curve of concrete

Hello,

As a first suggestion, I would recommend you give a close look to the exact meaning of the model parameters to isolate which are the one controlling the interaction strengths. (as for myself, I do not know CpmMat..)
Then try to reduce (a lot) them..

Jerome

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 <email address hidden>:

> 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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Thanks Jérôme Duriez.

Thanks Jan Stránský. It solved my question.