为什么铁芯受力这么小，有什么方法可以增大吗？求高手帮忙呀！

/PREP7
/TITLE,HZX
ET,2,PIANE53
KEYOPT,1,3,1
MP,MURX,1,1
MP,MURX,2,1
MP,MURX,3,2000
/com,
n=600
i=1.0
acoil=6
H=0.04
L=0.015
gap=0.0005
LZN=0.05
D=0.01
AH=0.1
AW=0.08
POS=0.005
jdens=n*i/acoil
/PNUM,AREA,1
RECTNG,0,AW/2,0,AH
RECTNG,0,D/2,POS,LZN
RECTNG,D/2+0.0005,L+0.0005,0.045,0.045+H
ALLSEL,ALL
AOVLAP,ALL
NUMCMP,AREA
APLOT
ASEL,S,AREA,,1
AATT,3,1,2,0
ASEL,S,AREA,,2
AATT,2,1,2,0
ASEL,S,AREA,,3
AATT,1,1,2,0
ALLSEL,ALL
APLOT
SMRTSIZE,3
AMESH,ALL
ESEL,S,MAT,,3
CM,ARM,ELEM
FMAGBC,'ARM'
ALLSEL,ALL
ARSCAL,ALL
FINISH
/SOLU
ESEL,S,MAT,,2
BFE,ALL,JS,1,,,jdens
ESEL,ALL
NSEL,EXT
D,ALL,AZ,0
ALLSEL,ALL
FINISH
/SOLU
MAGSOLV
SAVE
FINISH

/POST1
PLF2D
FMAGSUM
PLVECT,B,,,,VECT,ELEM,ON
/GRAPHICS,POWER
AVRES,2
PLNSOL,B,SUM
FINISH