Only one atom is being created while running 3D-crack simulation using peri package

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1

Dear all
I’m trying to perform the 3D crack simulation of a metal using peridynamic package.

While doing so, only atom is being created and hence I cannot apply velocity to the system.
I am sharing the input script here, kindly take a look.

Thank you

2d peridynamic crack simulation

units si
dimension 3
boundary s s p

atom_style peri
neighbor 0.0001 bin
neigh_modify delay 5

create geometry

lattice bcc 0.00287
#lattice structure and constant will change with metal
region box block 0 0.1 0 0.1 -0.01 0.01
create_box 5 box
create_atoms 1 box

#mass 1 1.0
#mass 2 1.0
#mass 3 1.0
#mass 4 1.0
#mass 5 1.0

peridynamic potentials

pair_style peri/eps
pair_coeff * * 1.6e11 8.4e10 0.0015001 0.0005 0.25 25e7

define groups

region 1 block INF INF INF 0.001 INF INF
group lower region 1
region 2 block INF INF 0.099 INF INF INF
group upper region 2
group boundary union lower upper
group mobile subtract all boundary

region leftupper block INF 0.05 0.05 INF INF INF
region leftlower block INF 0.05 INF 0.05 INF INF
group leftupper region leftupper
group leftlower region leftlower

set group leftupper type 2
set group leftlower type 3
set group lower type 4
set group upper type 5

initial velocities

compute new mobile temp
velocity mobile create 0.01 887723 temp new
velocity upper set 0.0 0.3 0.0
velocity mobile ramp vy 0.0 0.3 y 0.001 0.099 sum yes

compute stress all stress/atom NULL

fixes

fix 1 all nve
fix 2 boundary setforce NULL 0.0 0.0

run

timestep 0.003
thermo 200
thermo_modify temp new

neigh_modify exclude type 2 3

#dump 1 all atom 500 dump-v3.crack
dump 1 all custom 100 dump-v3.crack.* id type x y z vx vy vz c_stress[1] c_stress[2] c_stress[3]

#dump 2 all image 250 image.*.jpg type type &

zoom 1.6 adiam 1.5

#dump_modify 2 pad 4

dump 3 all movie 100 dump-v3.mp4 type type &
zoom 1.6 adiam 1.5
dump_modify 3 pad 4

run 10000

2

You are creating a region that is covering less than one lattice cell, so only one atom can fit into it (the one placed at the origin).

Please take note of the “units” keyword to the region command and that its default value is “lattice”.

3

Thank you for the reply,
but lattice constant is provided is very less compared to the region created.

4

Please re-read the region command documentation very carefully about the “units” keyword and its effect. Once you understand this, everything will make sense.

1 Like
5

Thank you. I have rectified the error in region part (region box block 0 0.1 0 0.1 -0.01 0.01 units box).
But the log file shows
“Peridynamic bonds:
total # of bonds = 0
bonds/atom = 0”
Is there any specific reason for that?

6

LAMMPS will compute what your input tells it to compute. What is meaningful input is something that you need to figure out based on the physics of the model and the specific parameters that you enter. If you are not familiar with Peridynamics, then you need to find somebody that is (the preferred option) or try to learn it by yourself from the relevant publications and the descriptions in the LAMMPS documentation.