method peridynamics eps

Hello,

I have some problem with the method eps because when I launch the simulation, I have logical value for stress at the beginning but after,temperature increases strongly and the computation can´t be made :

     100 0 36.15723 0
     1000 45.951168 36.15723 0.63390809
     2000 99.088874 36.15723 0.1213101
     3000 149.74134 36.15723 0.6776301
     4000 203.82692 36.15723 4.9518453
     5000 nan 36.244641 nan
     6000 nan 36.244641 nan
     7000 nan 36.244641 nan

I tried by decreasing the timestep even until 10-8 but it didn´t work.

Do you have any idea to solve this numerical problem ?

Thanks for your consideration

Simon Bourreau

INPUT File :

# 3D peridynamic simulation for traction

units nano
dimension 3
boundary s s s
atom_style peri
atom_modify map array
neighbor 0.1 bin
lattice sc 0.3615

#define all the parts

region beam block 0 36.15 0 2.169 0 2.169 units box
create_box 1 beam
create_atoms 1 region beam

region leftbc block 0 1.0845 0 2.169 0 2.169 units box
group leftbc region leftbc
region rightbc block 35.0655 36.15 0 2.169 0 2.169 units box
group rightbc region rightbc

group boundary union leftbc rightbc

group middle_atoms subtract all boundary

pair_style peri/eps
pair_coeff * * 37000 27750 1.0845 2.6 0.1 40

set group all density 8960e-6

set group all volume 0.047241

run 100

velocity all set 0.0 0.0 0.0 sum no units box

fix 1 middle_atoms nve

compute peratom middle_atoms stress/atom NULL

compute sigmaxx middle_atoms reduce sum c_peratom[1]

variable sigmavolxx equal c_sigmaxx/(0.94*vol)

fix 2 rightbc move linear 1.8075 0 0 units box
fix 3 leftbc move linear -1.8075 0 0 units box

timestep 0.005e-3 #0.005

thermo 1000
thermo_style custom step v_sigmavolxx lx temp

dump 1 all custom 4100 peri_6_nano_eps_res.txt id x y z
dump_modify 1 append yes

run 20000

# SIMULATION DONE

print "All done"

I assume it is just bad dyanmics, due to
bad input. Rezwan may want to comment.

Steve

Yes, I also think that its just bad dynamics. you can change the critical bond stretch, timestep size (smaller) etc to see if it improves.

I assume it is just bad dyanmics, due to
bad input. Rezwan may want to comment.

Steve