tow engines in a program

Hello Alireza,

> I am a beginner in YADE

welcome :-)

> I want to use an engine for moving the particles

Please describe your needs more in detail. From the description I have the feeling that simply moving the piston is enough and the rest would be the "reaction"..

cheers
Jan

Hello Jan,

Thank you very much for your response. I want to simulate a simple model which have a mold and piston and particles in there. I applied a engine for movement of particles caused by gravity, after that I want to compress particles by the piston to find force chain in the system during compaction.

Bests

Alireza

> I applied a engine for movement of particles caused by gravity

yes, NewtonIntegrator(...,gravity=[0,0,-9.8]) does this

> after that I want to compress particles by the piston

your TranslationEngine is ok.

There are several options how to make it work, e.g. I would add the piston with TranslationEngine after gravity deposition ends.

cheers
Jan

Hi,
You can impose the velocity of the piston as b.state.vel=(x,y,z) after
setting b.state.blockedDOFs='xyzXYZ'. You then make it zero in the begining
and change for something else at some point.
TranslationEngine makes this simple thing excessively complex in my
opinion. I would suggest to forget it (*).
Bruno

(*) and even to remove it from source code for its anti-didactic effect, to
keep only truly involved helico-rotational motion engines present

Le jeu. 26 juil. 2018 16:43, Jan Stránský <
<email address hidden>> a écrit :

> Question #671132 on Yade changed:
> https://answers.launchpad.net/yade/+question/671132
>
> Status: Open => Answered
>
> Jan Stránský proposed the following answer:
> > I applied a engine for movement of particles caused by gravity
>
> yes, NewtonIntegrator(...,gravity=[0,0,-9.8]) does this
>
> > after that I want to compress particles by the piston
>
> your TranslationEngine is ok.
>
> There are several options how to make it work, e.g. I would add the
> piston with TranslationEngine after gravity deposition ends.
>
> cheers
> Jan
>
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Hello Jan,

Thank you for your response. I can't run it. it gives me the error:

TypeError: No registered converter was able to produce a C++ rvalue of type int from this Python object of type Body

when I run the below engines:

#================== engine for movement of particles =========================

O.engines=[
      ForceResetter(),
        InsertionSortCollider([Bo1_Box_Aabb(),Bo1_Sphere_Aabb()]),
        InteractionLoop(
          [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom()],
          [Ip2_FrictMat_FrictMat_FrictPhys()],
          [Law2_ScGeom_FrictPhys_CundallStrack()]
        ),

      NewtonIntegrator(damping=0.4,gravity=[0,0,-9.8],label="newton"),
]

#================== engine for movement of piston ===========================

O.engines=[
       ForceResetter(),
         InsertionSortCollider([Bo1_Box_Aabb(),Bo1_Sphere_Aabb()]),
         InteractionLoop(
          [Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
          [Ip2_JCFpmMat_JCFpmMat_JCFpmPhys()],
          [Law2_ScGeom_JCFpmPhys_JointedCohesiveFrictionalPM()]
       ),
       NewtonIntegrator(damping=0,gravity=[0,0,-9.8],label="newton",),

       TranslationEngine(translationAxis=[0,0,-5],velocity=0.5,ids=pst)

     GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=10,timestepSafetyCoefficient=0.4, defaultDt=0.1*utils.PWaveTimeStep()),
]

O.dt=.5*PWaveTimeStep()

O.saveTmp()

Bests

Alireza

Hello,

next time, please try to create a MWE [1]. Now we don't know what pst is (**probably** the source of the problem, see below):
Also please insert complete error messages, now we don't know where the error comes from :-)

Also note that kinematic engines (like TrnaslationEngine) should come before NewtonIntegrator [2].

cheers
Jan

[1] https://yade-dem.org/wiki/Howtoask
[2] https://yade-dem.org/doc/user.html#base-engines

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