crack with peridynamic theory

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1

thanks for answers

I have a problem about crack .I made changes to the code that you see below. And by applying force and speed, my plate should be cut off from the notch and pre-crack. but this does not happen, and only the tension in the area has increased.
Thanks for your advice.

#this is my file
units si
dimension 3
boundary s s p
atom_style peri
atom_modify map array
neighbor 0.0012 bin

create geometry

lattice sc 0.0006
region plate block -0.0125 0.0125 -0.0285 0.0285 -0.004 0.004 units box

create_box 7 plate
create_atoms 1 region plate
region center_circle sphere 0 0 0 0.005 units box
group center_circle region center_circle
delete_atoms group center_circle
region crack block -0.0125 -0.0095 0 0.0002 -0.004 0.004 units box
group crack region crack
delete_atoms group crack
pair_style peri/lps
pair_coeff * * 2.89e9 1.05e9 0.002005 0.03867 0.22
pair_coeff 3 4 2.89e9 1.05e9 0 0.03867 0.22
set group all density 1180
set group all volume 36e-8
velocity all set 0.0 0.0 0.0 sum no units box

region 4 block INF INF -0.0095 0 INF INF units box
group low region 4
region 5 block INF INF 0.0002 0.0095 INF INF units box
group up region 5

set group low type 4
set group up type 5

fix 1 all nve

velocity up set 0 0.0005 0 units box

Raplace

fix 4 up setforce 0 3.09e8 0

velocity low set 0 -0.0005 0 units box

Raplace

fix 3 low setforce 0 -3.09e8 0

compute 1 all damage/atom
timestep 3e-8
thermo 20
dump 1 all custom 20 dump.lammpstrj id x y z c_1
dump 2 all xyz 20 dump.xyz
run 500

2

thanks for answers
I have a problem about crack .I made changes to the code that you see below. And by applying force and speed, my plate should be cut off from the notch and pre-crack. but this does not happen, and only the tension in the area has increased.

you are simulating for only 500 MD steps. nothing much can happen in
such a short simulation. if you look very closely, you *will* see,
that your atoms are actually moving. try running for 5000 steps
instead.

you should also see, that you have constructed a very bad model. if
you also output the atom type in your (custom) dump file and color the
atoms by it (like in the attached picture), you will see, that you are
moving the atoms just where the crack is (magenta and cyan colored
atoms). that makes no sense. with fix setforce you wipe out the forces
previously computed by the pair style and basically turn your
simulation in a meaningless animation. you would have to pull atoms at
the right and left end instead. also, you are moving with a set
velocity *and* a set force, that means, the velocity of the pulling
will increase constantly. is that what you want? normally, people
would want a constant velocity. for that, however, you have to set all
forces to zero on those atoms (or do not use fix nve on them but
instead use fix move to have them follow a prescribe motion, e.g.
linear).

axel.

vmdscene.jpg