Learning Forum

[vgiordano3]

Hi everyone,

I'm conducting a vibrational analysis simulation. In the real case, the structure is loaded with 176 pounds of weight and excited with a PSD spectrum. I've done the spectral analysis (SPER) after the mode extraction and then combined the modes. Then I've done the static analysis. How can I combine the results given by the modal cqc combination and the static analysis to obtain the complessive stress of the structure? I tried using the following commands:

 

!MODEL

...

!Static Analysis

/solu

antype,static

...

/post1
lcdef,1

!Modal and spectral analysis

...

/post1 

lcfile,2,file,mcom     !file.mcom stores the cqc results

lcoper,add,1

lcoper,add,2

This way didn't work.

Thank you in advance!

 

[Chandra Sekaran]

you cannot use 'lcfile,2,file,mcom'. file.mcom is not a load case file. It has APDL command instructions to combine various modes. 

a) The SPRS results are obtained by squaring mode shapes and taking square root. So all the signs are lost. So you may want to do SRSS of static and SPRS results.Refer to https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v222/en/ans_bas/Hlp_G_BAS5_4.html?q=lcoper for documentation on load case operations

b) below is a version to simply add static and sprs results. You will need to modify this to do the SRSS.

/post1

/input,file,mcom    ! combine modes to get sprs results

lcwrite,2  ! write the combined results as load case 2

file,....   ! point to the static results file

set,last  ! read the last set of static results

lcoper,add,2   ! add the results in database with load case 2

 

[vgiordano3]

Hi Chandra, thanks for your answer. Can you be more specific on how to do SRSS of static and SPRS results? My case is the following:

I tried doing Static analysis and SPRS analysis separately and the sum of the two case is less than the static case only. I guess the problem is in the fact that signs are lost. Thank you in advance! 

 

fini
/clear

!
!DIMENSIONS
h=0.76            
l=1.41            
w=0.8            
ws=0.003        
wcer=0.020        
lc1=0.30575       
lc2=1.1065        
lcc1=0.32575       
lcc2=1.0865        
hc1=0.18075-0.05        
hcc1=0.20075-0.05    
hc2=0.67925-0.05        
hcc2=0.65925-0.05   
wc1=0.16575        
wc2=0.66425        
tc=1.5e-3        
h1=0.515        
h2=0.415        
w1=0.29       
w2=0.49      
w3=0.54        

ls1=0.273       
ls2=1.137        
hs1=0.622-0.05       
hs2=0.522-0.05       

lunghezzacer=0.135
lcera1=lc1+0.1
lcera2=lcera1+0.1
lcerb2=lc2-0.1
lcerb1=lcerb2-0.1
lcerc1=lc1+0.040
lcerc2=lcerc1+lunghezzacer
lcerd1=lc1+((lc2-lc1)/2)-(lunghezzacer/2)
lcerd2=lcerd1+lunghezzacer
lcere2=lc2-0.040
lcere1=lcere2-0.135

hcer2=hcc2-0.01
hcer1=hcc1+0.01

lcop1=lcc1+0.01
lcop2=lcc2-0.01
hcop1=hcc1+0.01
hcop2=hcc2-0.01

wh1=40e-3                
th1=4e-3

!UPN160
wu1=65e-3
wu2=160e-3
tu1=10.5e-3
tu2=7.5e-3

E=210e+9    !Modulo di young acciaio
ni=0.3    !Coefficiente di Poisson acciaio 
        !e AISI304
rho=7850    !Densità acciaio
E1=196e+9    !Modulo di young AISI304
rho1=7910    !Densità AISI304

rho2=3500    !Densità ABS
E2=70e+6    !Modulo di young ABS
ni2=0.37    !Coefficiente di Poisson ABS

/prep7
!Spigoli telaio
k,1 $ k,2,l $ k,3,l,,w $ k,4,,,w
k,5,,h $ k,6,l,h $ k,7,l,h,w $ k,8,,h,w
k,9,,h1 $ k,10,l,h1 $ k,11,,h,w1 $ k,12,l,h,w1
k,13,,h,w2 $ k,14,l,h,w2 $ k,15,,h,w3
k,16,l,h,w3 $ k,17,,h2

!keypoint fissaggio staffe-upn160
k,46,lc1,h1 $ k,47,lc2,h1 
k,48,lc1,hs1 $ k,49,lc1,hs2
k,50,lc2,hs1 $ k,51,lc2,hs2
k,52,lc1,h1,w1 $ k,53,lc1,h1,w3
k,54,lc2,h1,w1 $ k,55,lc2,h1,w3

!Spigoli cassetta
k,18,lc1,hc1,wc1 $ k,19,lc2,hc1,wc1
k,20,lc2,hc1,wc2 $ k,21,lc1,hc1,wc2
k,22,lc1,hc2,wc1 $ k,23,lc2,hc2,wc1
k,24,lc2,hc2,wc2 $ k,25,lc1,hc2,wc2

!Spigoli staffe
k,27,lc1,h,w1 $ k,28,lc1,hs1,w1 $ k,29,lc1,hs2,w1

k,31,lc1,h,w3 $ k,32,lc1,hs1,w3 $ k,33,lc1,hs2,w3

k,35,lc2,h,w1 $ k,36,lc2,hs1,w1 $ k,37,lc2,hs2,w1

k,39,lc2,h,w3 $ k,40,lc2,hs1,w3 $ k,41,lc2,hs2,w3

k,42,lcc1,hcc2,wc2 $ k,43,lcc1,hcc1,wc2

k,44,lcc2,hcc2,wc2 $ k,45,lcc2,hcc1,wc2

!KEYPOINT CERNIERE/CHIUSURE
k,56,lcera1,hcc2,wc2 $ k,57,lcera2,hcc2,wc2
k,58,lcera2,hcer2,wc2 $ k,59,lcera1,hcer2,wc2

k,60,lcerb1,hcc2,wc2 $ k,61,lcerb2,hcc2,wc2
k,62,lcerb2,hcer2,wc2 $ k,63,lcerb1,hcer2,wc2

k,64,lcerc1,hcer1,wc2 $ k,65,lcerc2,hcer1,wc2
k,66,lcerc2,hcc1,wc2 $ k,67,lcerc1,hcc1,wc2

k,68,lcerd1,hcer1,wc2 $ k,69,lcerd2,hcer1,wc2
k,70,lcerd2,hcc1,wc2 $ k,71,lcerd1,hcc1,wc2

k,72,lcere1,hcer1,wc2 $ k,73,lcere2,hcer1,wc2
k,74,lcere2,hcc1,wc2 $ k,75,lcere1,hcc1,wc2

!KEYPOINT COPERCHIO
k,76,lcop1,hcop2,wc2 $ k,77,lcop2,hcop2,wc2
k,78,lcop2,hcop1,wc2 $ k,79,lcop1,hcop1,wc2
!Rinforzo coperchio
k,80,lcop1,hcop2,wc2-0.01 $ k,81,lcop2,hcop2,wc2-0.01
k,82,lcop2,hcop1,wc2-0.01 $ k,83,lcop1,hcop1,wc2-0.01

!KEYPOINT RINFORZO STAFFE
k,84,lc1-0.03,hs1 $ k,85,lc1-0.03,hs1,w3
k,86,lc2+0.03,hs1,w3 $ k,87,lc2+0.03,hs1

!Ritti
l,1,17 $ l,17,9 $ l,9,5 $ l,2,10 
l,10,6 $ l,3,7 $ l,4,8

!Traversi e longheroni
l,1,2 $ l,2,3 $ l,3,4 $ l,4,1
l,5,6 $ l,6,12 $ l,12,14 $ l,14,16 $ l,16,7
l,7,8 $ l,8,15 $ l,15,13 $ l,13,11 $ l,11,5
l,11,12 $ l,13,14 $ l,15,16

!Montante
l,9,46 $ l,46,47 $ l,47,10

!Traverse oblique
l,17,2 $ l,1,8 $ l,6,3

!Aree relative alla cassetta
a,18,22,28,29    !A1
a,22,25,32,28    !A2
a,28,32,33,29      !A3
a,21,33,32,25    !A4
a,18,29,33,21      !A5
a,18,22,23,19    !A6
a,18,19,20,21      !A7
a,22,23,24,25    !A8
a,19,37,36,23      !A9
a,23,36,40,24    !A10
a,36,37,41,40      !A11
a,20,24,40,41    !A12
a,19,20,41,37    !A13

!Aree rinforzi cassetta
a,25,42,43,21                !A14
a,25,24,44,61,60,57,56,42        !A15
a,24,20,45,44                !A16
a,20,21,43,67,66,71,70,75,74,45        !A17

!Aree staffe orizzontali
a,48,28,52,46    !A18
a,46,52,29,49    !A19
a,28,32,53,52    !A20
a,52,53,33,29    !A21
a,36,50,47,54    !A22
a,47,51,37,54    !A23
a,36,40,55,54    !A24
a,54,55,41,37    !A25

!Aree cerinere
a,56,57,58,59    !A26 
a,60,61,62,63    !A27
a,64,65,66,67    !A28
a,68,69,70,71    !A29
a,72,73,74,75    !A30

!Area coperchio
a,76,59,58,63,62,77,78,73,72,69,68,65,64,79    !A31
!Aree rinforzo coperchio
a,76,59,58,63,62,77,81,80            !A32
a,77,81,82,78                    !A33
a,82,83,79,64,65,68,69,72,73,78            !A34
a,76,79,83,80                    !A35

!Aree rinforzo staffe
a,48,28,32,85,84                !A36
a,50,36,40,86,87                !A37

!Tipologia elementi,materiali e sezioni
et,1,beam188,,,3                !Beam 188 con f.f. cubica
sectype,1,beam,hrec,tubquad        !Sezione tubolare quad
secdata,wh1,wh1,th1,th1,th1,th1    !Dati sezione tubolare quad

sectype,2,beam,chan,upn160        !Sezione upn160
secdata,wu1,wu1,wu2,tu1,tu1,tu2    !Dati sezione upn 160

et,2,shell63                !Shell163
!Definizione del materiale 1 Acciaio strutturale
mp,ex,1,E                !Modulo Young material 1
mp,nuxy,1,ni                !Coeff poisson material 1
mp,dens,1,rho                !Densità material 1
!Definizione materiale 2 Acciaio inox
mp,ex,2,E1                !Modulo Young material 2
mp,nuxy,2,ni                !Coeff Poisson material 2
mp,dens,2,rho1                !Densità material 2
!Definizione materiale 3 ABS
mp,ex,3,E2                !Modulo di Young material 3 ABS
mp,nuxy,3,ni2                !Coeff di Poisson material 3 ABS
mp,dens,3,rho2                !Densità ABS

                    !Spessore dello shell cassetta

r,2,ws                    !Spessore dello Shell delle staffe

r,3,wcer                !Spessore cerniere

 

!Meshing

!Mesh telaio
esize,0.05
lsel,r,line,,1,24
latt,1,,1,,,,1    
lmesh,all
lsel,all

esize,0.05
lsel,r,line,,28,30
latt,1,,1,,,,1    
lmesh,all
lsel,all

lsel,r,line,,25,27
k,1000,,+1e+12
latt,1,,1,,1000,,2
lmesh,all
lsel,all

!Mesh cassetta
asel,r,area,,1,17
type,2
r,1,tc
mat,2
allsel,all

asel,r,area,,31,35
type,2
r,1,tc
mat,2
allsel,all

!Mesh staffe
asel,r,area,,18,25
type,2
r,2,ws
mat,2
allsel,all

asel,r,area,,36,37
type,2
mat,2
r,2,ws
allsel,all

!Mesh chiusure
asel,r,area,,26,27
type,2
mat,3
r,3,wcer
allsel,all

!Mesh cerniere in acciaio
asel,r,area,,28,30
type,2
mat,2
r,3,wcer
allsel,all
esize,0.02
amesh,all

/eshape,1,1
eplo

!vincoli
ksel,r,kp,,1,4,1
nslk,r,n,all
d,all,all
allsel,all

!ANALISI STATICA
!Definzione carico statico
asel,r,area,,7
sfa,all,,pres,2000
sbctran
allsel,all

/solu
antype,static
allsel,all
outres,all,all
outpr,all,all
save
solve
finish

/post1
set,last
reswrite,static
file,static,rst

!ANALISI MODALE

/solu
antype,modal,new
modopt,lanb,all,10,500
!mxpand,,,,yes,,,
allsel,all
outres,all,all
outpr,all,all
solve
finish

/solu
antype,spectrum,new
spopt,sprs,,yes
svtyp,2
sed,0.0,1.0,0.0
! DEFINIZIONE SPETTRO DI RISPOSTA DELLA STRUTTURA
freq,10,24.9,40,49.9,74.9
freq,124.9,149.9,174.9,199.9,249.9
freq,274.9,299.9,324.9,349.9,374.9
freq,399.9,424.9,449.9,474.9,499.9
sv,,6.1025,6.1025,6.1025,4.9883,3.4447
sv,,2.1612,1.8300,1.5899,1.4076,1.1484
sv,,1.0528,0.9725,0.9040,0.8450,0.7934
sv,,0.7481,0.7079,0.6719,0.6396,0.6104
! FINE DEFINIZIONE SPETTRO DI RISPOSTA
dmprat,0.00001        ! Coefficiente di smorzamento
allsel,all
outres,all,all
outpr,all,all
solve
finish

/solu
antype,modal,new
modopt,lanb,all,10,500
mxpand,,,,yes,,,
allsel,all
outpr,all,all
outres,all,all
solve
finish

! COMBINAZIONE QUADRATICA DEI MODI

/solu
antype,spectrum,new
cqc,0.001,disp
allsel,all
outpr,all,all
outres,all,all
solve
finish

 

/post1    
/input,file,mcom 
lcwrite,2
file,static,rst
set,last
lcoper,add,2