如何求边界应力？求教

美丽新世界

如何求出侧面边界和底面不同区域的应力。模拟的是用一平板压缩装在容器中的颗粒体。请教各位大侠！！
new
set disk on
wall id=1 nodes ( 0, -10) (5, -10)
wall id=2 nodes (5, -10) (5, 0)
wall id=3 nodes (5, 0) ( 0, 0)
wall id=4 nodes ( 0, 0) ( 0, -10)
gen id=1,3000 rad 0.04,0.041 x=0,5 y=-10,-0.5
plot
wall id=1 kn=1e8 ks=1e11
wall id=2 kn=1e8 ks=1e11
wall id=3 kn=1e8 ks=1e11
wall id=4 kn=1e8 ks=1e11

prop density 2600 kn 1e9 ks 1e9
prop rad mul 1.51
set hist_rep = 5
history ball yvel (3, 0)
history diagnostic muf
set dt dscale
cycle 5000
plot
set grav 0,-9.81
property fric 1.0
cycle 1000
plot create Contact Force
plot set title text 'Model at equilibrium'
plot add ball lblue
plot add wall black
plot add cforce black
plot add axes brown
plot show
save foot1.sav
plot print view
plot print item
plot show <viewname>
delete wall 3
wall id 10 nodes (5,0) (0,0)
wall id 10 ks 1e8 kn 1e8 fric 1.0
wall id 10 yvel = -0.3e-3
property n_bond=5e5 s_bond=5e5
hist wall yforce id 10
cycle 2000
plot current 0
plot hist 3
plot
print ball
print wall
print info