我在一个硅片的某个区域加载了热流密度并应用表面效应单元同时加载了对流,然后其他面加载了对流,进行了热分析
我用热分析的结果作为载荷又进行了热应力分析,但是在热应力分析的时候出现的错误提示是:Large negative pivot value ( -1.349587109E-12 ) in Eqn.system. May be
because of a bad temperature-dependent material property used in the
model.
请问应该怎眼去修改呢?
我不知道应该怎样去解决这个问题
命令流如下:
!假设硅对激光的吸收率为0.9,激光照射直径为150μm,长1.5mm,宽200μm,厚度40μm
fini
/clear
/filename,danliang
/title,thermal analysis of beam
/prep7
et,1,solid90
et,2,surf152
mp,kxx,1,140 !定义硅片的导热系数
!mp,dens,1,2230
KEYOPT,2,3,0 ! OMEG 用于全局笛卡儿坐标系X轴
KEYOPT,2,4,0 !有中间节点
KEYOPT,2,5,0 !关于额外节点的辐射或对流计算: 无额外节点
!KEYOPT,2,6,0 !使用体积温度,额外节点温度作为体积温度
KEYOPT,2,7,0 !对于膜层散热系数不增加经验项
KEYOPT,2,8,3 !根据表面温度计算对流系数
KEYOPT,2,9,0 !不包括热辐射
k,1,0,0,0.2e-3
k,2,1.5e-3,0,0.2e-3
k,3,1.5e-3,0.04e-3,0.2e-3
k,4,0,0.04e-3,0.2e-3
k,5,0,0,0
k,6,1.5e-3,0,0
k,7,1.5e-3,0.04e-3,0
k,8,0,0.04e-3,0
l,1,2
l,2,3
l,3,4
l,4,1
l,3,7
l,7,8
l,8,4
l,1,5
l,5,8
l,2,6
l,6,7
l,5,6
al,1,2,3,4
al,2,10,11,5
al,12,11,6,9
al,9,7,4,8
al,1,10,12,8
al,3,5,6,7
va,1,2,3,4,5,6
lsel,s,,,1,3,2
lsel,a,,,6,12,6
lesize,all,,,100
lsel,s,,,2,4,2
lsel,a,,,9,11,2
lesize,all,,,4
lsel,s,,,7,8,1
lsel,a,,,5,10,5
lesize,all,,,20
type,1
vmesh,all
!生成表面效应单元
asel,s,,,6
nsla,s,0
type,2
esurf,all
alls
fini
/solu
!antype,static
toffst,273
allsel,all
ic,all,temp,25
!施加对流载荷
esel,s,type,,1
asel,s,,,1,6,1
asel,u,,,6
nsla,s,1
sf,all,conv,10,25 !定义对流
alls
esel,s,type,,2
nsle,s,1
sf,all,conv,12.5,25 !定义对流
!施加一个直径为150μm的激光均匀热流密度
esel,s,type,,1
nsle,s
nsel,s,loc,x,0.6e-3,0.75e-3
nsel,r,loc,y,0.04e-3
nsel,r,loc,z,0.025e-3,0.175e-3
sf,all,hflux, 88108 !施加均匀热流密度
alls
solv
fini
!将热分析的结果用于应力分析中
/prep7
et,1,solid95
mp,dens,1,2230 !硅的密度
mp,ex,1,1.3e5 !硅的杨氏模量
mp,prxy,1,0.28 !硅的泊松比
mp,alpx,1,7.8e-6 !硅的热膨胀系数
nsel,s,loc,x,0
nsel,r,loc,y,0,0.04e-3
nsel,r,loc,z,0,0.2e-3
d,all,ux,0,,,uy,uz
fini
/solu
tref,298 !定义参考温度
ldread,temp,,,,,danliang,rth
alls
solv
fini |