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Re: About SDEC packing
yuannian wang a écrit :
*/Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>/* wrote:
1/ Random generation in a box (without contact - without gravity).
2/ Radii expansion until one prescibed value of the confining
3/ Possibly : decreasing slowly the contact friction to densify
The packings obtained are homogeneous and isotropic, and you can
the final porosity and the relative particle size distribution.
It is the only method I know that combine all those aspects.
Thanks for your information! Seems good. I guess your method is a
dynamic way for packing.(?)
You are right, it is dynamic.
Yes, it costs more time. But geometric ways of packing have drawbacks
that can be real issues or not, depending on what you want to simulate :
the compacity can't be user-defined, some methods don't give isotropic
Packing for 10000 spheres in 2D : about 1,5h. In 3D : about 3h (the
increase in time between 2D/3D is not so dramatic). Simulation of a
compression test on the generated sample is about 2 or 3 times more, and
you can perform many tests on one sample. So yes it costs, but it is not
the major cost in most simulations.
I agree however that it could be good to have one quick geometric method
when one does not want to wait.
Generally dynamic approach will cost more time than purely
geometric way. How long will it run a packing, like saying, for
10,000 spheres in 2D? Also for 3D problem, the computation
consumption will increase dramatically.
Personnaly, I will need a dynamic method.
I could share my 2D code without problem but it is written in Fish
langage (langage of PFC, the commercial DEM code from Itasca). I think
it would be useless for you.
We may have to consider this. Can you share your 2D packing code
to me? Let's see if I can modify it into 3D. If it works I'll back
the 3D code to you guys.
Today, I will try to write the algorithm and send it to you.
We need :
- a random number generator
- a dynamic engine (Yade will do the job ;))
- the code for simulating rigid walls and for measuring the pressure on
the walls (I have already written this for Yade and I can send it to you)
- the code for increasing/decreasing the size of particles depending on
the measured pressure (not done)
- the code for decreasing contact friction.(not done)
- the code for computing compacity (I can do it very quikly).
I will also send you the code I have already written in Yade for
triaxial tests, it is not in the current release of Yade.
In the triaxial test, there is already one box with grains floating
inside (with positions from the text file small.sdec.xyz if I remember
well...) and walls applying confining pressure.
Maître de conférence
Institut National Polytechnique de Grenoble
Laboratoire 3S (Soils Solids Structures) - bureau I08
BP 53 - 38041, Grenoble cedex 9 - France
Tél : 04.56.52.86.21
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