ansys导线短路温度场仿真出现了负值

hulululu

在ansys温度场求解时温度出现了负值或低于最初的设定值（20℃）

我的模型是两根铜导线搭接到一起，中间短路点被碳化（选用炭材料）导线外有绝缘皮。给导线通短路电流，并计算产生的温度场。

在求解计算时，我不加绝缘皮（只有两根铜导线和中间的炭化点）时不存在温度降低的情况，可是加上绝缘皮后就出现了负值的温度点。

不知道是什么原因，有人说是网格不够细致，可是我细化了网格后还是不行，不知道是不是边界加的有问题。

绝缘皮用加边界条件么，不知道怎么修改了。请求给位ansys高手的帮助，感激不尽~

程序

FINISH

/CONFIG,NRES,100000

/PREP7

ET,1,SOLID69

MP,DENS,1,8900

MPTEMP,,,,,,,,

MPTEMP,1,20,127,327,527,827,1027

MPTEMP,7,1083,1127,1227,1527

MPDATA,RSVX,1,1,1.678E-8,2.402E-8,3.792E-8,5.262E-8,7.551E-8,9.101E-8

MPDATA,RSVX,1,7,12.237E-8 ,13.147E-8,14.613E-8,19.414E-8

MPTEMP,,,,,,,,

MPTEMP,1,20,100,300,500,900,1083

MPTEMP,7,1200,1500,1800,2200,2700,3000

MPDATA,C,1,1,380,394,410,428,474,520

MPDATA,C,1,7,533,545,556,575,598,612

MPTEMP,,,,,,,,

MPTEMP,1,20,77,127,227,327,527

MPTEMP,7,727,927

MPDATA,KXX,1,1,403,396,393,386,379,366

MPDATA,KXX,1,7,352,339

MPTEMP,,,,,,,,

MPTEMP,1,20,1072,1084,1200,1600,2000

MPTEMP,7,2586,2596,2900

MPDATA,ENTH,1,1,0,3.5579E9,2.5329E10,2.358E11,9.6149E11,1.687E12

MPDATA,ENTH,1,7,2.725E12,3.149E12,3.165E12

MP,DENS,2,1870

MP,RSVX,2,0.0000012

MP,KXX,2,400

MPTEMP,,,,,,,,

MPTEMP,1,20,100,300,500,900,1200

MPTEMP,7,1800,2100,2300,2500,2700,3000

MPDATA,C,2,1,645,1020,1323,1604,1901,2010

MPDATA,C,2,7,2152,2211,2248,2290,2338,2401

ET,2,SOLID90

MP,DENS,3,1380

MP,KXX,3,100

MP,C,3,1580

MP,RSVX,3,10E11

建模

/VIEW,1,1,1,1   

/ANG,1  

/REP,FAST

CYLIND,0.00089,0,0,0.025,0,360,   

wpoff,,,0.0245  

wpro,,,90.000000

BLOCK,0.0005,,0.0005,,0.0032,,  

wpro,,,-90.000000   

wpoff,0.0035,,-0.001

CYLIND,0.00089,0,0,0.025,0,360,  

VSBV, 2, 1   

VSBV,4,3  

CYLIND,0.00089, ,0,0.025,0,360,

wpoff,-0.0035,,-0.0235

CYLIND,0.00089, ,0,0.025,0,360,   

CYLIND,0.00169, 0.00089,0,0.023,0,360,

wpoff,0.0035,,0.0255

CYLIND,0.00169,0.00089 ,0,0.023,0,360,

VGLUE,ALL

NUMCMP,ALL

VSEL,S,,,4

VSEL,A,,,5

VATT,1, ,1, 0   

VSEL,S,,,1

VATT,2, ,1,0

VSEL,S,,,2

VSEL,A,,,3

VATT,3, ,2, 0   

网格划分

LSEL,S,,,1

LSEL,A,,,2

LSEL,A,,,5

LSEL,A,,,7

LSEL,A,,,63

LSEL,A,,,65

LESIZE,ALL,,,10

LSEL,S,,,29

LSEL,A,,,30

LSEL,A,,,31

LSEL,A,,,32

LSEL,A,,,3

LSEL,A,,,4

LSEL,A,,,8

LSEL,A,,,6

LESIZE,ALL,,,3

LSEL,S,,,62

LSEL,A,,,64

LESIZE,ALL,,,2

LSEL,S,,,19

LSEL,A,,,22

LSEL,A,,,39

LSEL,A,,,18

LSEL,A,,,23

LSEL,A,,,38

LSEL,A,,,20

LSEL,A,,,21

LSEL,A,,,40

LSEL,A,,,17

LSEL,A,,,24

LSEL,A,,,37

LSEL,A,,,11

LSEL,A,,,14

LSEL,A,,,48

LSEL,A,,,12

LSEL,A,,,13

LSEL,A,,,47

LSEL,A,,,10

LSEL,A,,,15

LSEL,A,,,49

LSEL,A,,,9

LSEL,A,,,16

LSEL,A,,,50

LESIZE,ALL,,,8

LSEL,S,,,27

LSEL,A,,,28

LSEL,A,,,33

LSEL,A,,,34

LSEL,A,,,26

LSEL,A,,,35

LSEL,A,,,25

LSEL,A,,,36

LSEL,A,,,45

LSEL,A,,,52

LSEL,A,,,46

LSEL,A,,,51

LSEL,A,,,44

LSEL,A,,,53

LSEL,A,,,43

LSEL,A,,,54

LESIZE,ALL,,,14

LSEL,S,,,41

LSEL,A,,,42

LSEL,A,,,57

LSEL,A,,,58

LSEL,A,,,55

LSEL,A,,,56

LSEL,A,,,59

LSEL,A,,,60

LESIZE,ALL,,,57

ALLSEL

VSWEEP,5,8,9

VSWEEP,4,6,7

VSWEEP,3,14,22

VSWEEP,2,10,19

VSWEEP,1,2,4

求解计算

/SOLU

ANTYPE,TRANS

TIMINT,ON

TUNIF,20

AUTOTS,ON

ASEL,S, , , 7

NSLA,S,1

D,ALL,VOLT,0

ASEL,S, , , 8

NSLA,S,1

CP,1,VOLT,ALL

NI=NDNEXT(0)

ALLSEL

T=1E-8                 设置开始求解时间

DL=600                电流有效值

TZ=0.01                结束时间

N=100                 一个周期的步数

F=50                  频率

PI=2*ASIN(1)          获得π值

CON=1/F/N            设置时间步长

NEQIT,1               设置时间步的迭代次数

*CREATE,LOAD        创建宏设置载荷步

TIME,T                设置载荷步时间

I=DL*1.414*SIN(2*PI*F*T)        计算激励电流

F,NI,AMPS,I             加载电流

T=T+CON              时间递增

SOLVE

*END                   结束宏命令

*DO,I,1,TZ/CON+1        循环命令

*USE,LOAD           执行宏      

*ENDDO                结束循环命令

FINISH

/POST1

SET,LAST

PLNSOL,TEMP