Multiple materials

Submitted by cstoltz on Thu, 09/23/2010 - 18:36

Christoph,

Is it possible to define multiple materials in a simulation, and if so, do you have any example scripts that do this? I haven't been able to figure this out yet. For example, I want to be able to assign different friction properties for particle-particle and particle-wall interactions.

Thanks,
Chris

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ckloss's picture

ckloss | Thu, 09/23/2010 - 19:01

Hi Chris,

sure - this is possible - just take any of the standard examples and change the following commands:

create_box 2 reg
fix m1 all property/global youngsModulus peratomtype 5.e6 1.e6
fix m2 all property/global poissonsRatio peratomtype 0.45 0.4
fix m3 all property/global coefficientRestitution peratomtypepair 2 0.7 0.6 0.6 0.55
fix m4 all property/global coefficientFriction peratomtypepair 2 0.05 0.01 0.01 0.025

this would be a case with 2 materials; coefficientRestitution would be 0.7 for a contact material1-material1, 0.6 for material1-material2, and 0.55 for material2-material2

Christoph

xinze_l | Thu, 12/02/2010 - 16:21

I want to assign different parameter properties for particle-particle and particle-wall interactions， e.g type 1 particle and type2 particle with Young Modulus 2.4e6, while type 1 particle and wall1 (leftWall.stl) with Young Modulus 1.3e5, and type 1 particle and wall2 (rightWall.stl) with Young Modulus 3.2e5. How I will reach it. Would you give me some examples, Thank you in advance!

xinze

cgrohs | Tue, 09/28/2010 - 10:16

Additional information:
I also had troubles using multiple materials (bug?) but found a work around. At first I used two materials (number 1 for particles, number 2 for walls) which worked without problems (with create_box 2). Then I tried to add a third material (create_box 3) for additional particles poured into the model in an additional step (=new run command after unfixing the first fix pour). => Error at beginning of the first step because the number of atom types was not correct (?!?). Setting "create_box 2" lead to correct calculation of the first step but an error at the beginning of the second step (that's ok) because the number of atom types was not correct.

Work around:
Using "create_box 3", starting with pouring atom type 3 in the first step and using atom type 1 in the second step seems to work. Maybe one always has to use the highest atom type number for the particles poured in the first step of the simulation?

Hope this information is useful!
Regards,
Christian