tatiana.pais
Guest
Good morning.
I would like to calculate the spectrum of the response speed of a plate excited by a shaker.
during experimental tests the plate was rested on the resilients, so I thought of modeling them as springs using the combin14 elements.
if they place six soft at the ends of the plate and block all dof at the extreme of the spring that in reality would be connected with the ground, my fem program does not work. the result of speed is zero. if instead besides blocking all the dofs of the end of the springs, I also block the translations in the spring that is connected to the plate, then I have results.
I do not understand why the first program (locking only one end of the spring) does not work .
Is there anyone who can help me? ? ?
Thank you! ! !
/prep7
et,1,shell281
et,2,beam188
et,3,combin14,0,1
et,4,combin14,0,2
et,5,combin14,0,3
sectype,1,shell,thick6mm
6,1,0,3
sectype,2,shell,thick4mm
secreted, 4,1,0,3
sectype,3,beam, l,0
secoffset,user,0,57.57.5
secdata,40,60,5.5,0,0,0,0,0,0,0,0
mp,ex,1,210000
mp,nuxy,1,0.3
mp,dens,1,7.8e-9
mptemp,1,0
♪
h=3000
w ==
♪
♪
♪
♪
r,1,kx
r,2,ky
r,3,kz
0, 0, 0
K,2, l, 0, 0
k,3, l, h, 0
K,4, 0, h, 0
K,5,l,h,w
♪
a,2,3,5,6
a,1,2,4
Agen, 11,2, , , , , , ,
Asel,all
aglue,all
I, I, I...
mshkey,1
esize,s
amesh,2
amesh,13,24,1
aplot
I'm sorry.
mshkey,1
esize,s
amesh,1
Isel,none
No.
*do,i,1.5
lsel,a,loc,x,n
No!
*end
I'll be right back.
lesize,s
lmesh,all
No,0,0,-86
No, 3300,0,-86
No, 3300,3000,-86
No,0,3000,-86
type,5
real,3
e,1,3466
e,2822,3467
e,2828,3468
e,68,3469
nsel,s,node,3466,3469,1
d,all,all
No, 86,0
No, 3386,0,0
No, 3386,3000,0
No, 86,3000,0
type,3
real,1
e,1,3470
e,2822,3471
e,2828,3472
e,68,3473
nsel,s,node,3470,3473,1
d,all,all
No.
No, 3300,-86,0
No, 3300,3086,0
No,0,3086,0
type,4
real,2
e,1,3474
e,2822,3475
e,2828,3476
e,68,3477
nsel,s,node,3474,3477,1
d,all,all
finish
/solu
antype,modal! modal analysis
sopt,lanb,500 reduced method
save
solve! initiates solution
finish
expand the modes
Re-enter solution
Expass,on expansion pass
mxpand,500, ,yes! number of modes to expand
The
finish
Getting the spectrum solution
Re-enter solution
antype,spectr spectrum analysis
spopt,psd,500,yes! power spectral density; no. of modes; Calcs stress. on/off
psdunit,1,forc! type of spectrum
psdfrq,1,50,63,80,100,125,160,200
psdfrq,1,250,315,400,500,630,800,1000
psdfrq,1,1250,1600! frequency pts. (for values spectrum vs. frequency tables)
7.2.17,2.17,0.67,0.54
psdval,1,0.43,0.34,0.27,0.218,0.216,0.13,0.17
psdval,1,0.13,0.06 spectrum values
dmprat,0.02! damping ratio
f,3249,fx,1 base excitation
pfact,1,node! calculate participation factors
psdres, velo,rel! output controls
save
The
finish
combine modes using psd method
Re-enter solution
antype,spectr spectrum analysis
psdcom, ,500, ,total! psd mode combinations with importance and
option for select a subset of modes for
combination!
The
finish
/post1! enter post1
set,4,1! read results from appropriate load step, substep
/post26! enter post26
store,psd! store frequency vector (variable 1)
nsol,2,2600,u,z
rpsd,3,2,2,2,rpsd-z! calculation response psd (variable 3)
pltime,50,1600
/axlab,x,frequency(hz)
/axlab,y,psd (v^2/hz)
/title, versus input spectrum-velocity psd
int1,10,3,1,intpsd
plvar,3 plot the response psd
plvar,10
/optput
I would like to calculate the spectrum of the response speed of a plate excited by a shaker.
during experimental tests the plate was rested on the resilients, so I thought of modeling them as springs using the combin14 elements.
if they place six soft at the ends of the plate and block all dof at the extreme of the spring that in reality would be connected with the ground, my fem program does not work. the result of speed is zero. if instead besides blocking all the dofs of the end of the springs, I also block the translations in the spring that is connected to the plate, then I have results.
I do not understand why the first program (locking only one end of the spring) does not work .
Is there anyone who can help me? ? ?
Thank you! ! !
/prep7
et,1,shell281
et,2,beam188
et,3,combin14,0,1
et,4,combin14,0,2
et,5,combin14,0,3
sectype,1,shell,thick6mm
6,1,0,3
sectype,2,shell,thick4mm
secreted, 4,1,0,3
sectype,3,beam, l,0
secoffset,user,0,57.57.5
secdata,40,60,5.5,0,0,0,0,0,0,0,0
mp,ex,1,210000
mp,nuxy,1,0.3
mp,dens,1,7.8e-9
mptemp,1,0
♪
h=3000
w ==
♪
♪
♪
♪
r,1,kx
r,2,ky
r,3,kz
0, 0, 0
K,2, l, 0, 0
k,3, l, h, 0
K,4, 0, h, 0
K,5,l,h,w
♪
a,2,3,5,6
a,1,2,4
Agen, 11,2, , , , , , ,
Asel,all
aglue,all
I, I, I...
mshkey,1
esize,s
amesh,2
amesh,13,24,1
aplot
I'm sorry.
mshkey,1
esize,s
amesh,1
Isel,none
No.
*do,i,1.5
lsel,a,loc,x,n
No!
*end
I'll be right back.
lesize,s
lmesh,all
No,0,0,-86
No, 3300,0,-86
No, 3300,3000,-86
No,0,3000,-86
type,5
real,3
e,1,3466
e,2822,3467
e,2828,3468
e,68,3469
nsel,s,node,3466,3469,1
d,all,all
No, 86,0
No, 3386,0,0
No, 3386,3000,0
No, 86,3000,0
type,3
real,1
e,1,3470
e,2822,3471
e,2828,3472
e,68,3473
nsel,s,node,3470,3473,1
d,all,all
No.
No, 3300,-86,0
No, 3300,3086,0
No,0,3086,0
type,4
real,2
e,1,3474
e,2822,3475
e,2828,3476
e,68,3477
nsel,s,node,3474,3477,1
d,all,all
finish
/solu
antype,modal! modal analysis
sopt,lanb,500 reduced method
save
solve! initiates solution
finish
expand the modes
Re-enter solution
Expass,on expansion pass
mxpand,500, ,yes! number of modes to expand
The
finish
Getting the spectrum solution
Re-enter solution
antype,spectr spectrum analysis
spopt,psd,500,yes! power spectral density; no. of modes; Calcs stress. on/off
psdunit,1,forc! type of spectrum
psdfrq,1,50,63,80,100,125,160,200
psdfrq,1,250,315,400,500,630,800,1000
psdfrq,1,1250,1600! frequency pts. (for values spectrum vs. frequency tables)
7.2.17,2.17,0.67,0.54
psdval,1,0.43,0.34,0.27,0.218,0.216,0.13,0.17
psdval,1,0.13,0.06 spectrum values
dmprat,0.02! damping ratio
f,3249,fx,1 base excitation
pfact,1,node! calculate participation factors
psdres, velo,rel! output controls
save
The
finish
combine modes using psd method
Re-enter solution
antype,spectr spectrum analysis
psdcom, ,500, ,total! psd mode combinations with importance and
option for select a subset of modes for
combination!
The
finish
/post1! enter post1
set,4,1! read results from appropriate load step, substep
/post26! enter post26
store,psd! store frequency vector (variable 1)
nsol,2,2600,u,z
rpsd,3,2,2,2,rpsd-z! calculation response psd (variable 3)
pltime,50,1600
/axlab,x,frequency(hz)
/axlab,y,psd (v^2/hz)
/title, versus input spectrum-velocity psd
int1,10,3,1,intpsd
plvar,3 plot the response psd
plvar,10
/optput