Issues on "peri3dController_triaxialCompression.py"

Asked by janaka kumara

I have few isues as mentioned below when I use peri3dController_triaxialCompression.py to simulate triaxial tests for Toyoura sand.
1. Whats "initSize"?. I use specimen (sand) of 200mm in heigh and 100mm in diameter in labaratory experiments. How can I simulate same conditions in Yade using "initSize?
2. When I change "initSize" and radius in "sp=pack.randomPeriPack(radius=.........), into 0.1 and 0.0002285 respectively, Yade didnt work properly and gave that ..............
Considering packing (radius=0.05+or-0, N=986, dim=0.00431044x0.00431044x0.00431044,periodic,scale=0.00457), created Tue Jun 27 03:12:03 2011
REJECT: initSize differs too much from scaled packing size.
Does this mean that there are limits on "initSize" and "radius"? If so, what are those limits?

Note: D50 of sand used is 0.0002285m. I though thats equal to radius . I also thought "initSize" means diameter of the specimen, thats why I used 0.1m above.

Could you please explain where I did mistakes and how I could correct them.

Thank you.

Regards,
Janaka,

PhD candidate,
Geotechnical laboratory,
Department of Civil Engineering,
Yokohama National University,
Japan

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Luc Scholtès
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Jan Stránský (honzik) said :
#1

Hi Janaka,

>1. Whats "initSize"?. I use specimen (sand) of 200mm in heigh and 100mm in diameter in labaratory experiments. How can I simulate same conditions in Yade using "initSize?
peri3dController uses periodic boundary conditions on an aligned block. The initial sphere packing is created by periodic (means using periodic boundary conditions) triaxial compression from randomly placed spheres placed in a block (cell) with __initSize__ dimensions. This dimensions is then reduced by the compression, so the block is smaller then initSize.

>2. When I change "initSize" and radius in "sp=pack.randomPeriPack(radius=.........), into 0.1 and 0.0002285 respectively, Yade didnt work properly and gave that ..............
>Considering packing (radius=0.05+or-0, N=986, dim=0.00431044x0.00431044x0.00431044,periodic,scale=0.00457), created Tue Jun 27 03:12:03 2011
>REJECT: initSize differs too much from scaled packing size.
>Does this mean that there are limits on "initSize" and "radius"? If so, what are those limits?
No. This only means, that saved packing does not satisfies conditions of current simulation (and is rejected) and new packing is creating.

>Note: D50 of sand used is 0.0002285m. I though thats equal to radius . I also thought "initSize" means diameter of the specimen, thats why I used 0.1m above.
initSize is Vector3(x,y,z) where x,y,z are initial dimensions of periodic cell, so it is not cylindrical..

Regards
Jan

Revision history for this message
janaka kumara (janaka-eng) said :
#2

Hi Honzik,

Thank you very much for your details.

>Does this mean that there are limits on "initSize" and "radius"? If so, what are those limits?
No. This only means, that saved packing does not satisfies conditions of current simulation (and is rejected) and new packing is creating.

Here, do you have any idea when (how long) does new packing finish creating? I run one case with initSize 0.1162 (that gives a volume equivalen to 100mm diameter and 200mm height cylindrical volume as my laboratory tests) and radius 0.0002285, but even after 20 hours, I didnt get results. However, this time, there are two lines of "REJECT: initSize differs too much from scaled packing size". Will this give results after some time, e.g. few more hours later?

Thank you.

Regards,
Janaka

Revision history for this message
Best Luc Scholtès (luc) said :
#3

Hi Janaka,

Sorry I can't help you concerning the error you get, but I am wondering, are
you trying to create a model with around 9e6 particles? From your message, I
came to this conclusion doing:

NbParticles=specimenVolume/spheresVolume=(100*100*200)/(1.333*pi*0.23)=9e6

If it is the case, it is normal that your simulation takes so long, and I
would recommend not to use so much particles. Usually, you can model a
granular material using around 10 000 particles. If it is not the case, just
forget what I say...

By the way, welcome to YADE community

Cheers

  Luc

2011/6/29 janaka kumara <email address hidden>

> Question #162989 on Yade changed:
> https://answers.launchpad.net/yade/+question/162989
>
> Status: Answered => Open
>
> janaka kumara is still having a problem:
> Hi Honzik,
>
> Thank you very much for your details.
>
> >Does this mean that there are limits on "initSize" and "radius"? If so,
> what are those limits?
> No. This only means, that saved packing does not satisfies conditions of
> current simulation (and is rejected) and new packing is creating.
>
> Here, do you have any idea when (how long) does new packing finish
> creating? I run one case with initSize 0.1162 (that gives a volume
> equivalen to 100mm diameter and 200mm height cylindrical volume as my
> laboratory tests) and radius 0.0002285, but even after 20 hours, I didnt
> get results. However, this time, there are two lines of "REJECT:
> initSize differs too much from scaled packing size". Will this give
> results after some time, e.g. few more hours later?
>
> Thank you.
>
> Regards,
> Janaka
>
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Revision history for this message
janaka kumara (janaka-eng) said :
#4

Thanks Luc Scholtès, that solved my question.

Revision history for this message
janaka kumara (janaka-eng) said :
#5

Hi Luc,

Thank you. Now, I know what happened there, thats really what you said.

Regards,
Janaka