模拟声波在混凝土中传播，网格尺寸应当如何确定。。求大神指教。。

模拟声波在混凝土中传播，本人选择加汗宁窗的8周期的振源信号，振源主频40kHz，力作用在节点上，但是当对网格尺寸的大小不知如何确定，网格尺寸过细，ansys显示求解错误。。网格尺寸大写，则计算结果与实际不符。。以下为命令流，用后处理软件画出节点坐标为（0.4，0，5）的v-t图形。。求相关领域专家指导。。。/FILENAME,ZZ1
/UNITS,SI
/config,nres,5000
/PREP7
/VIEW,,1,2,3
!/PLOPTS,INFO,1
!(1)定义材料属性
ET,1,SOLID164
MP,EX,1,4.0e10
MP,DENS,1,2200
MP,NUXY,1,0.2
!MP,DAMP,1,0.00005
!(2)建模，划分网格
CYL4,0,0,0,0,0.4,360,10
VATT,1,,1,0
wprota,0,0,90
vsbw,all
allsel
wprota,0,-90,0
vsbw,all
allsel
lsel,s,,,15,16
LESIZE,ALL,0.02
allsel
lsel,s,,,20
LESIZE,ALL,0.02
allsel
lsel,s,,,22
LESIZE,ALL,0.02
allsel
lsel,s,,,1,4
LESIZE,ALL,0.02
allsel
lsel,s,,,10
LESIZE,ALL,0.02
allsel
vsweep,all
ALLSEL,ALL
!(3)施加约束、边界条件
asel,s,loc,z,10
nsla,s,1
d,all,all
asel,s,loc,z,0
nsla,s,1
cm,ding,node
EDNB,add,ding,1,1 !定义桩顶为不反射边界
asel,s,loc,z,10
nsla,s,1
cm,di,node
EDNB,add,di,1,1 !定义桩底为不反射边界
!(4)定义时间与荷载序列(主频40kHz)
*dim,time,array,201,1,1,,,
*dim,fcc,array,201,1,1,,,
*do,i,1,201,1
*SET,time(i,1,1),(i-1)*0.000001
*SET,fcc(i,1,1),-sin(0.08*3.1415926*(i-1))
*SET,fcc(i,1,1),0.5*fcc(i,1,1)*(1-cos(0.01*3.1415926*(i-1)))
*enddo
!(5)选择加载点
wpcsys,-1
allsel
nsel,s,loc,x,-0.4
nsel,r,loc,y,0
nsel,r,loc,z,5
cm,act1,node
allsel,all
!加载
edload,add,fx,0,act1,time,fcc,0
ALLSEL,ALL
FINISH
!(6)求解参数设置
/SOLU
TIME,0.002
edrst,5000
edhtime,5000
EDOPT,ADD,,LSDYNA
!(7)求解
SOLVE