关于材料多线性弹塑性模型 本例子这里为什么不能加载到塑性阶段？

/PREP7

R=5            !圆棒中间半径

L=30               !中间部分长度

N,1            !建立坐标0,0,0编号为1的节点

N,2,,,20       !建立坐标0,0,0编号为1的节点

CYL4,0,0,0,0,R,360,L

ET,1,SOLID186

mp,ex,1,350000  

mp,dens,1,7850 

mp,nuxy,1,0.3

tb,miso,1,,19

TBPT,,0.001,350

TBPT,,0.019528,368

TBPT,,0.021498,378.56995

TBPT,,0.022958,385.048

TBPT,,0.026098,395.59561

TBPT,,0.027558,400.67664

TBPT,,0.031078,413.76315

TBPT,,0.037628,427.80426

TBPT,,0.043658,440.46487

TBPT,,0.049868,451.05673

TBPT,,0.062768,468.46252

TBPT,,0.068458,475.77029

TBPT,,0.075338,483.85168

TBPT,,0.086028,490.07611

TBPT,,0.099158,500.12592

TBPT,,0.124118,510.44119

TBPT,,0.148118,516.65851

tbplot,miso,1

ESIZE,2.5,0, 

VSWEEP,ALL

ASEL,S,LOC,Z,0     

*GET,N_AREA1,AREA,,NUM,MAX

ALLSEL

ASEL,S,LOC,Z,L

*GET,N_AREA2,AREA,,NUM,MAX

ALLSEL

ESIZE,2.5,0, 

VSWEEP,ALL

/SOL

ANTYPE,4

TRNOPT,FULL

LUMPM,0

NSUBST,1,0,0  

OUTRES,ERASE

OUTRES,ALL,ALL

KBC,0          !Ramp load

TIME,1

DA,N_AREA2,ALL,0

SFA,N_AREA1,1,PRES,0

LSWRITE,1,

TIME,2

SFA,N_AREA1,1,PRES,-200      

LSWRITE,2,  

TIME,3

SFA,N_AREA1,1,PRES,-320

LSWRITE,3,  

TIME,4  

SFA,N_AREA1,1,PRES,-450

LSWRITE,4, 

LSSOLVE,1,4,1,

加载到第四步就不收敛了  求高手赐教，感谢！