求助大佬，我做了一个普通两端固支梁，在升温下挠度的变化，但是有一段随着温度的升高挠度却下降了，和理论分析不符，怀疑是bfe命令使用有误，命令流如下：


finish
/CLEAR
/FILENAME,1
*DIM,LIANG,,360
*CREATE,SC,MAC
*VREAD,LIANG(1),D:\ANSYSGZ\BOOK_APDL\TEMP_SLL,TXT
(F12.6)
*CFCLOS
*END
SC
/PREP7
/UNITS,SI  
ET,1,BEAM188
MPREAD,D:\ANSYSGZ\BOOK_APDL\GANG,SI_MPL
SECTYPE,1,BEAM,RECT
SECDATA,250,750
K,1
K,2,5000
K,3,1500,1,0
L,1,2
LATT,1,,1,,,3,1
LESIZE,ALL,,,10
LMESH,ALL
FINISH

/SOLU
KSEL,S,,,1,2
NSLK,S
D,ALL,ALL
ALLSEL,ALL
F,7,FY,-1000
ALLSEL,ALL
TRNOPT,FULL
PRED,ON
SOLCONTROL,ON
SOLVE
*DO,I,20,1800,20
TIME,I
BFE,ALL,TEMP,,LIANG(I/20)
BFE,ALL,TEMP,5,LIANG(I/20)
ALLSEL,ALL
SOLVE
*ENDDO
FINISH

/POST1
ALLSEL
NSORT,U,Z,0,1     !最大应力节点编号的提取 排序，0为降序 1为升序，0为实数 1为绝对值

/POST26
*GET,MAX_Z,SORT,0,IMAX      !*GET, Par, SORT, 0, Item1
NSOL,3,7,U,Y,U_1
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