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[lammps-users] Nanoindentation of Graphene
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[lammps-users] Nanoindentation of Graphene


From: Jit Sarkar <jitsarkar1993@...24...>
Date: Mon, 17 Jul 2017 10:07:16 +0530

Dear All,

I am trying to simulate nanoindentation experiment on single layer graphene sheet using a diamond indenter. The problem I am facing is that, as the indentation process is going on the indenter is simply passing through the graphene sheet without causing any deformation to the sheet. For this reason, I am getting the load vs indentation depth graph with an incorrect trend with the load fluctuating from negative to positive and vice-versa.

I have attached my program and simulation file for convenience.

Thanks in advance.

Thanks
Best Regards,
JIT
____________________________________________________
Jit Sarkar (B.Tech)
Junior Project Assistant & Research Scholar (MS)
Department of Metallurgical and Materials Engineering
Indian Institute of Technology, Kharagpur-721302, India
########## Nanoindentationof a single graphene sheet ###########


#--------------Initialize Simulation--------------------------

echo screen
dimension	3
units           metal
atom_style      atomic

#--------------Create Atoms-----------------------------------

boundary	s s p

region	box block 0.0 400 0.0 700 -100 100 units box
create_box	2 box

lattice   custom 2.465 a1 1.0 0.0 0.0 a2 0.5 1.0 0.0 &
basis 0.0 0.0 0.0 basis 0.25 0.25 0.0

region	graphene block 0.0 400 0.0 700 0.0 0.1 units box
create_atoms	1 region graphene 

lattice diamond 3.567
region mobile sphere 200 350 25 20 units box
create_atoms	2 region mobile

group substrate region graphene
group indenter region mobile

mass 1 28.086
mass 2 12.011

#--------------Define Interatomic Potential-------------------

pair_style	tersoff/zbl
pair_coeff	* * ./FeC_Henriksson_2013.tersoff.zbl C

#---------Run the simulation for thermal equilibration--------

fix 1 all npt temp 298.0 298.0 0.01 iso 0.0 0.0 0.05

thermo		10
thermo_style	custom step pe ke etotal temp lx ly lz press atoms

dump 1 all cfg 1000 radiation.*.cfg mass type xs ys zs
dump 2 all custom 1000 dump.Graphene id x y z vx vy vz
log log.Graphene_EQM

timestep 0.001

run 100

#-------------Run the simulation for indentation--------------

unfix 1

velocity substrate set 0.0 0.0 0.0

fix 2 indenter move linear 0.0 0.0 -0.1 units box
fix 3 substrate indent 10 sphere 200 350 25 20 units box

compute 1 indenter com
compute 2 substrate reduce sum fz

thermo		1
thermo_style	custom step c_1[3] c_2 

log log.Graphene_IND

timestep 0.001

run 50000

###

unfix 2
unfix 3

run 50000 
#################################################################



Attachment: FeC_Henriksson_2013.tersoff.zbl
Description: Binary data