Dear Lammps users,
I’m trying to shear an edge dislocation in iron.
Before applied the strain, I relaxed the internal pressure such that the Pxx,Pyy and Pzz is about 200~300 MPa.
And then I change BC to ppp and defined three region (R1) upper block which added a constant dispacement, which strain rate is 1.0e8 s-1. (R2) mobile region whch is under NVT (R3) lower block which is fixed not to move during shear.
But when I plot the stress-strain curve, the max stress is about 800 MPa.
Could someone help me with this ?
Below is my input to create dislocation:
dimension 3
units metal
boundary p p s
atom_style atomic
lattice bcc 2.8665 orient x 1 1 1 orient y -1 -1 2 orient z 1 -1 0
create_box 1 box
create_atoms 1 box
region del block 109.711 111.711 INF INF INF 50 units box
delete_atoms region del
#–pair
pair_style eam/fs
pair_coeff * * Fe.eam.fs Fe
neighbor 2 bin
neigh_modify delay 0 every 1 check yes
timestep 0.001
#–create edge dislocation
region up block INF INF INF INF 50 INF units box
region d1 block INF 109.711 INF INF INF 50 units box
region d2 block 111.711 INF INF INF INF 50 units box
group up region up
group d1 region d1
group d2 region d2
fix 1 all nve
fix 2 all setforce 0 0 0
velocity d1 ramp vx 0 0.5 x 10 15
velocity d2 ramp vx -0.5 0 x 15 20
run 500
unfix 1
unfix 2
fix 1 all box/relax iso 0.0
minimize 0 0.001 10000 10000
unfix 1
minimize 1e-10 1e-10 10000 10000
#–shear
velocity lower set 0.0 0.0 0.0
fix 1 lower setforce 0 0 0
fix 2 mobile nvt temp 300 300 0.01
fix 3 upper move linear 0.0084 0 0 units box
velocity mobile ramp vx 0 0.0084 z 9 93 units box
run 300000
Best wishes,
Jeaha
從 Windows 10 的郵件傳送