91 lines
2.6 KiB
Plaintext
91 lines
2.6 KiB
Plaintext
# Squish three pillars with different Poisson's ratios
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# going from nearly incompressible to auxetic
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# from left to right, nu ~ 0.5, 0.25, 0, <0
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# calibration from DOI: 10.1039/d3sm01373a
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units lj
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dimension 3
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boundary p p s
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atom_style bond
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special_bonds lj 0.0 1.0 1.0 coul 0.0 1.0 1.0
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newton on off
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comm_modify vel yes cutoff 2.6
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lattice fcc 1.41
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region box block 0 20 -10 10 -1 21 units box
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create_box 4 box bond/types 4 extra/bond/per/atom 20 extra/special/per/atom 50
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mass * 1.0
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# Create initial disordered geometry somewhat near jamming
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region pillar cylinder z 10.0 0.0 7.0 0.0 20.0 units box
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region pillarw cylinder z 10.0 0.0 8.0 -1.0 21.0 units box
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create_atoms 1 region pillar
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velocity all create 0.1 345910
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pair_style bpm/spring
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pair_coeff * * 1.0 1.0 1.0
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fix 1 all nve
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fix wtemp all wall/region pillarw harmonic 1.0 1.0 1.0
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thermo_style custom step ke pe pxx pyy pzz
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thermo 100
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timestep 0.1
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run 20000
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unfix wtemp
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# Replicate cylinder and add bonds
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replicate 4 1 1
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region r1 block 0.0 20.0 EDGE EDGE EDGE EDGE side in units box
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region r2 block 20.0 40.0 EDGE EDGE EDGE EDGE side in units box
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region r3 block 40.0 60.0 EDGE EDGE EDGE EDGE side in units box
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region r4 block 60.0 80.0 EDGE EDGE EDGE EDGE side in units box
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group p1 region r1
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group p2 region r2
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group p3 region r3
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group p4 region r4
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set group p2 type 2
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set group p3 type 3
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set group p4 type 4
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velocity all set 0.0 0.0 0.0
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neighbor 1.0 bin
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create_bonds many p1 p1 1 0.0 1.5
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create_bonds many p2 p2 2 0.0 1.5
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create_bonds many p3 p3 3 0.0 1.5
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create_bonds many p4 p4 4 0.0 1.5
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neighbor 0.3 bin
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special_bonds lj 0.0 1.0 1.0 coul 1.0 1.0 1.0
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bond_style bpm/spring break no smooth no volume/factor yes
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bond_coeff 1 1.0 0 1.0 -0.8
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bond_coeff 2 1.0 0 1.0 0.0
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bond_coeff 3 1.0 0 1.0 2.0
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bond_coeff 4 1.0 0 1.0 10.0
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# squish
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region b block EDGE EDGE EDGE EDGE -1.0 2.0 units box
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region t block EDGE EDGE EDGE EDGE 18.0 21.0 units box
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group bot region b
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group top region t
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velocity top set 0.0 0.0 -0.0025
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fix 2 bot setforce 0.0 0.0 0.0
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fix 3 top setforce 0.0 0.0 0.0
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compute zmax all reduce max z
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thermo_style custom step ke pe pxx pyy pzz c_zmax
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#dump 1 all custom 100 atomDump id type x y z
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run 10000
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