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Re: [lammps-users] (no subject)


From: Michał Kański <michal.kanski@...2460...>
Date: Fri, 24 Nov 2017 12:42:59 +0000

LAMMPS calculates the variable as you asked – 25+step*dt*0.5, however, the first step after your “fix 4...” command  is 10000, hence the indenter starts at 30 not 25. You can either adjust the variable command or use “reset_timestep 0”.

 

Michal

 


From: Arun panda <arunkumarpanda123@...24...>
Sent: Friday, November 24, 2017 12:04:42 PM
To: lammps-users@lists.sourceforge.net
Subject: [lammps-users] (no subject)
 
Dear All,
i tried to simulate both loading and unloading process during nano indentation. Part of both input  and log script are mentioned below  for your reference.  The forces measured during loading  "30-step*dt*0.5" (30 angstrom to 25 angstrom) was fine where as after unfix command indentation is not following  the variable z equal "25+step*dt*0.5" (25 angstrom to 30 angstrom) rather it is following 30+step*dt*0.5 (30 angstrom to 35 angstorm ) , hence showing zero force by the indenter. Kindly, suggest  how the indentation will occur just after loading ? 
loading :
variable        z equal "30-step*dt*0.5" (30 =z coordinate +indenter radius(10 angstorm))
fix        3 mobile indent 10.0 sphere 40 40 v_z 10.0 units box
...


unloading :
unfix           3
variable        z equal "25+step*dt*0.5"
fix            4 mobile indent 10.0 sphere 40 40 v_z 10.0 units box
.
.
.

                                     30.1285            0            0            0
   10500    210.22726        30.25            0            0            0
   11000    212.04907         30.5            0            0            0
   11500    203.71086        30.75            0            0            0
   12000     212.6003           31            0            0            0
   12500    209.50829        31.25            0            0            0
   13000    200.34148         31.5            0            0            0
   13500    211.66192        31.75            0            0            0
   14000    196.25385           32            0            0            0
   14500    210.45152        32.25            0            0            0
   15000    214.95019         32.5            0            0            0
   15500    218.51511        32.75            0            0            0
   16000    210.86573           33            0            0            0
   16500    219.24366        33.25            0            0            0
   17000    212.23266         33.5            0            0            0
   17500    204.80275        33.75            0            0            0
   18000    224.66105           34            0            0            0
   18500    203.16825        34.25            0            0            0
   19000    208.72892         34.5            0            0            0
   19500    212.75782        34.75            0            0            0
   20000    207.28187           35            0            0            0
   20257    211.36393      35.1285            0            0            0


thank you in advance

with regards
Arun