螺栓预紧力施加(补充命令流)

finish
/clear
/prep7
block,-100,100,-100,100,0,10
block,-100,100,-100,100,-10,0
cm,lianjieban,volu
vsel,none
wpoffs,-50,-50
cylind,0,11,-10,10
wpoffs,,100
cylind,0,11,-10,10
wpoffs,100
cylind,0,11,-10,10
wpoffs,,-100
cylind,0,11,-10,10
cm,luoshuankong,volu
allsel,all
vsbv,lianjieban,luoshuankong
vsel,none
cylind,0,10,-20,20
rprism,-20,-10,6,20
rprism,10,20,6,20
vovlap,all
numcmp,all
vgen,2,all,,,-100
vgen,2,all,,,,100
wpcsys,-1
allsel,all
et,1,solid185
mp,ex,1,206e3
mp,prxy,1,0.3
tb,miso,1,1,3
vatt,1,1,1
mshape,0
mshkey,1
esize,8
vsweep,all
psmesh,1,volt01,,volu,18,0,z,0,,,,volt_01
此时，预紧面只在18号体中产生
如果把最后一行命令流改成先选择18号体
vsel,s,volu,,18
psmesh,1,volt01,,all,,0,z,0,,,,volt_01
则预紧面在所有螺栓中产生
有何办法
四个螺栓可以同时加预紧力吗，还是必须一个一个分开加