Particle Breakage in Granular Materials

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1

Hi All LAMMPS Users

I am trying to model uniaxial compression test in LAMMPS, my uniaxial test model is strain-rate dependent. In my physical tests, i used to see particle breakage. Is there anyway to see Particle Breakage of Granular Materials in LAMMPS? Do i need to write any specific fix command to see breakage in granular materials.

Thanks,

Sharif Islam

NYU Polytechnic School of Engineering

2

As with any simulation you can only observe what you model. As it stands, there is no out of the box solution for you. Granules are simply modeled as points from which surfaces can be defined, its really that simple. So it would be up to you to envision what you could do to model breakage, being particles pasted together which may break apart or destroying a particle producing 2 smaller pieces, but that much is up to you.

3

Thanks, Eric

I applied tremendous amount of load in my model, but i never saw a particle producing 2 smaller pieces from that. I used both Hook and Hertz Model and there is no difference.

Can you please suggest any command or fix which is appropriate and i can use in my code to paste particles together so that i can create agglomerate of grains.

Thanks,

Sharif Islam

NYU Polytechnic School of Engineering

4

Thanks, Eric

I applied tremendous amount of load in my model, but i never saw a particle
producing 2 smaller pieces from that. I used both Hook and Hertz Model and
there is no difference.

how should they break, if this is not part of the model? the size of
the granular particles is an input parameter!
eric already told you that.

Can you please suggest any command or fix which is appropriate and i can use
in my code to paste particles together so that i can create agglomerate of
grains.

there is no fix or command in LAMMPS that can do this. what you want
to do is a completely new model that you would have to derive,
implement (i.e. program into LAMMPS) and then parameterize for your
specific material.

as with other fundamental issues, it is highly recommended that you
discuss this issue with your adviser and get more detailed
explanations about what can and cannot be modeled by the available
models.

axel.

5

As Axel says, an individual particle is an indivisible
entity with some attributes, like size. It cannot “break”.

You can “glue” particles together by creating bonds
between them. See the bond_style command. You
can also break bonds. See the fix bond/break or
bond_style quartic commands. But those are different
models.

See also the PERI package for Peridynamic model

which is mesoscale/continumm package designed
for modeling fracture of materials.

Steve