简支梁的自振频率的问题

reino

/PREP7
ET,1,BEAM4
MP,EX,1,200E9
MP,NUXY,1,0.3
MP,DENS,1,8000
!MP,GXY,1,207E9/2.6
R,1,4,1.333,1.333,2,2,0
!RMORE,0,2.2496,1.177,1.177
!RMORE, R7, R8, R9, R10, R11, R12 Adds real constants to a set.

K,1,0
K,2,10
L,1,2
LESIZE,ALL,,,4      !changed
LMESH,1
/PNUM, NODE, 1
EPLOT
FINISH

/SOLU
ANTYPE,MODAL
MODOPT,SUBSP,7
MXPAND,7,,,1
SUBOPT,7
EQSLV,PCG
OUTPR,ALL,1                            ! Controls the solution printout
D,1,UX,0,0,1,1,UY,UZ,ROTX,ROTY          ! APPLY CONSTRAINTS
D,2,UY,0,0,2,1,UZ,ROTX,ROTY


PSOLVE,ELFORM
PSOLVE,TRIANG
PSOLVE,EIGREDUC
PSOLVE,EIGEXP
FINISH


/POST26
*GET,FREQ1,MODE,1,FREQ
*GET,FREQ2,MODE,2,FREQ
*GET,FREQ3,MODE,3,FREQ

/POST1
set,1,1
!/eshape,1                       
PLDISP,2                         ! Displays the displaced structure.
PRNSOL,U,Y                        ! Print the Nodal Solution results
/VIEW, 1, 2, 3, 9
/REPLOT                                !DEFINE the view angle
Set,LIST                        ! Listing all Frequencies


命令流如上，结果是只有一阶自振频率，而且当LESIZE中划分的单元数变化时，自振频率不变，请教大虾们，这是为什么？

reino

PSOLVE,EIGREDUC需要改为PSOLVE,EIGfull