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changmao

新虫 (初入文坛)

应助: 0 (幼儿园)
金币: 1.4
帖子: 7
在线: 1.9小时
虫号: 3460843
注册: 2014-10-08
专业: 凝聚态物性I:结构、力学和

[求助] lammps计算弹性模量应力应变已有1人参与

大家好，我现在在用lammps做弹性模量，在计算的过程中我发现有两个计算应力的，一个是通过 compute stress 另一个是press/v
我做的是y方向的拉伸，那我得应力是直接取stress或者press/v,还是用他们Y方向的分量？我只有10个金币，把我全部的金币都拿出来了，求大家指点，非常感激！我in文件如下
units             metal
boundary          p s p
atom_style       atomic
lattice             bcc 3.165 orient x 1 0 0 orient y 0 1 1 orient z 0 -1 1

region             box block 0 10 0 10 0 5
create_box       3 box
create_atoms    1 box
pair_style       eam/alloy
pair_coeff       * * W_zhou.eam.alloy W

neighbor       0.3 bin
neigh_modify       delay 0 every 1 check yes

region             lower block INF INF INF 0.9 INF INF
region             top block INF INF INF INF 8.9 INF
group             lower region lower
group             top region top
group             boundary union lower upper
group             mobile subtract all boundary

set             group lower type 2
set             group upper type 3
velocity       lower set 0.0 0.0 0.0

compute             new3d mobile temp
compute             new2d mobile temp/partial 1 0 1
compute       cna all cna/atom 3.0

compute stress all stress/atom
compute stressx all reduce sum c_stress[1]
compute stressy all reduce sum c_stress[2]
compute stressz all reduce sum c_stress[3]

# equilibrate
velocity       mobile create 300.0 85277 temp new3d
fix             1 all nve
fix             2 upper setforce 0.0 0.0 0.0
fix             4 lower setforce 0.0 0.0 0.0
fix             3 mobile temp/rescale 10 300.0 300.0 10.0 1.0
fix_modify       3 temp new3d
thermo             50
thermo_modify       temp new3d
timestep       0.001
run             100
variable tmp equal "ly"
variable L0 equal ${tmp}
variable strain equal "(ly-v_L0)/ly"
# shear
velocity       upper set 0 0.1 0
velocity       mobile ramp vy 0 0.1 y 0.9 8.9 sum yes
unfix             3
fix             3 mobile temp/rescale 10 300.0 300.0 10.0 1.0
fix_modify       3 temp new2d
variable p1 equal "v_strain"
variable p2 equal –{pzz/(3.165^3/2)}/10000
variable p3 equal –{pzz/(3.165^3/2)}/10000
variable p4 equal –{pzz/(3.165^3/2)}/10000
variable pm equal "" –{(pxx+pyy+pzz0/(3.165^3/2)}/10000
variable st  equal "step"
fix def1 all print 100 "${st} ${p1} ${pm}  ${p2} ${p3} ${p4}" file tensile_d.txt screen no
dump             1 all cfg 100 tensile_*.cfg mass type xs ys zs c_cna  c_stress[1] c_stress[2]  c_stress[3]
thermo             100
thermo_modify       temp new2d
reset_timestep       0
run             100000

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