求教关于摩擦滑动接触收敛的问题

heaventian

问题是这样的：一个块体A在一个弹簧的拉力作用下相对于块体B向右运动，块体A的自重提供摩擦阻力。弹簧用COMBIN14来模拟，块体A和B都用plan82来模拟，弹簧右端以0.1m/s的速度向右运动。请问为什么我做的结果总是不收敛？

!弹簧滑块模型，单个弹簧，单个滑块
FINISH
/CLEAR
/FILNAME,TEST9_12
/CONFIG,NRES,1E4
L=10
H=1
VEL_RIGHT=0.1

/PREP7
ET,1,PLANE82
ET,2,TARGE169
ET,3,CONTA172
ET,4,COMBIN14   
KEYOPT,4,1,0
KEYOPT,4,2,1
KEYOPT,4,3,0
R,1,,,, ,,  
RMORE,,,, ,,
RMORE,,,, ,,
RMORE,,,1, ,,   
R,2,300, , ,

MP,DENS,1,2E3
MP,EX,1,2.3E10
MP,PRXY,1,0.28  
MP,MU,1,0.05
RECTNG,,L,,H
RECTNG,,L/20,H,H+H/10
HPTCREATE,LINE,6,,RATIO,0.5,
AMESH,ALL
LSEL,S,LOC,X,0.5*L
LSEL,R,LOC,Y,H
NSLL,S,1
TYPE,2
ESURF
LSEL,S,LOC,X,0.25*L/10
LSEL,R,LOC,Y,H
NSLL,S,1
TYPE,3
ESURF
ALLSEL
NODE1=NODE(0.5*L/10,0.5*H/10+H,0)
N,1000,L/20+L/10,0.5*H/10+H
TYPE,4
REAL,2
E,NODE1,1000
SAVE
FINISH

/SOLU
!ANTYPE,TRANS
!EQSLV,,1e-4
NLGEOM,ON
T0=20
NSUBST,1000,2000,5
OUTRES,ALL,ALL  
AUTOTS,ON
KBC,0
LSEL,S,LOC,Y,0
NSLL,s,1
D,ALL,ALL,0
ALLSEL
N=50
*DO,I,1,N
TIME1=I*T0/N
TIME,TIME1 !总共滑动5分钟
D,1000,UX,VEL_RIGHT*TIME1 !弹簧右端滑动速度为1cm/s
lswrite,i
*ENDDO
ACEL,,10
LSSOLVE,1,N,1


/POST26
NSOL,2,NODE1,U,X,UX_BLOCK
NSOL,3,1000,U,X,UX_RIGHT
PLVAR,2,3
deriv,4,2,1
deriv,5,4,1