{"id":239467,"date":"2022-11-02T11:13:58","date_gmt":"2022-11-02T11:13:58","guid":{"rendered":"\/forum\/forums\/topic\/psd-analysis\/"},"modified":"2022-11-02T11:13:58","modified_gmt":"2022-11-02T11:13:58","slug":"psd-analysis","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/psd-analysis\/","title":{"rendered":"PSD analysis"},"content":{"rendered":"

Hello everyone. I’m having some difficulties performing a PSD analysis in Ansys APDL. I have a steel structure and a steel box, joined toghether with 4 brackets. This structure performed a vibrational test according to the MIL-STD-810. The PSD spectrum is the following (blue one) with 176lbs of weight on the box:<\/p>\n

<\/p>\n

I modeled the structure in Ansys with the spectrum analysis, but I’m having trouble with the mode combination.<\/p>\n

Here’s the code.<\/p>\n

\n
fini<\/div>\n
\/clear<\/div>\n
 <\/div>\n
!PARTE DICHIARATIVA<\/div>\n
!DIMENSIONI<\/div>\n
h=0.76 !Altezza telaio<\/div>\n
l=1.41 !Lunghezza telaio<\/div>\n
w=0.8 !Larghezza telaio<\/div>\n
wcer=0.020 !Spessore cerniere<\/div>\n
lc1=0.30575 !Dimensione 1 su x cassetta<\/div>\n
lcc1=0.32575 !Dimensione 1 su x nervatura N<\/div>\n
lc2=1.1065 !DImensione 2 su x cassetta<\/div>\n
lcc2=1.0865 !Dimensione 2 su x nervatura N<\/div>\n
ls1=0.273 !Dimensione 1 su x staffa<\/div>\n
ls2=1.137 !Dimensione 2 su x staffa<\/div>\n
hc1=0.18075 !Dimensione 1 su y cassetta<\/div>\n
hcc1=0.20075 !Dimensione 1 su y cassetta<\/div>\n
hc2=0.67925 !Dimensione 2 su y cassetta<\/div>\n
hcc2=0.65925 !Dimensione 2 su y nervatura N<\/div>\n
hs1=0.622 !Dimensione 1 su y staffa<\/div>\n
hs2=0.522 !Dimensione 2 su y staffa<\/div>\n
wc1=0.16575 !Dimensione 1 su z cassetta<\/div>\n
wc2=0.66425 !Dimensione 2 su z cassetta<\/div>\n
tc=1.5e-3 !Spessore lamiera cassetta<\/div>\n
bh=30e-3 !Dimensione 1 sezione staffa<\/div>\n
bb=6e-3 !Dimensione 2 sezione staffa<\/div>\n
 <\/div>\n
h1=0.515 !Altezza posiz staffa UPN160<\/div>\n
h2=0.415 !Altezza fissaggio traversa<\/div>\n
w1=0.29 !Posizione su z traversa sup 1<\/div>\n
w2=0.49 !Posizione su z traversa sup 2<\/div>\n
w3=0.54 !Posizione su z traversa sup 3<\/div>\n
 <\/div>\n
!DATI DELLE CERNIERE\/CHIUSURE<\/div>\n
!LUNGO X<\/div>\n
lunghezzacer=0.135<\/div>\n
lcera1=lc1+0.1<\/div>\n
lcera2=lcera1+0.1<\/div>\n
lcerb2=lc2-0.1<\/div>\n
lcerb1=lcerb2-0.1<\/div>\n
lcerc1=lc1+0.040<\/div>\n
lcerc2=lcerc1+lunghezzacer<\/div>\n
lcerd1=lc1+((lc2-lc1)\/2)-(lunghezzacer\/2)<\/div>\n
lcerd2=lcerd1+lunghezzacer<\/div>\n
lcere2=lc2-0.040<\/div>\n
lcere1=lcere2-0.135<\/div>\n
!LUNGO Y<\/div>\n
hcer2=hcc2-0.01<\/div>\n
hcer1=hcc1+0.01<\/div>\n
 <\/div>\n
!DATI COPERCHIO<\/div>\n
lcop1=lcc1+0.01<\/div>\n
lcop2=lcc2-0.01<\/div>\n
hcop1=hcc1+0.01<\/div>\n
hcop2=hcc2-0.01<\/div>\n
 <\/div>\n
!DATI DEL TUBOLARE QUADRATO<\/div>\n
wh1=40e-3<\/div>\n
th1=4e-3<\/div>\n
 <\/div>\n
!DATI DEL UPN160<\/div>\n
wu1=65e-3<\/div>\n
wu2=160e-3<\/div>\n
tu1=10.5e-3<\/div>\n
tu2=7.5e-3<\/div>\n
 <\/div>\n
!PARAMETRI DEL MATERIALE<\/div>\n
E=210e+9 !Modulo di young acciaio<\/div>\n
ni=0.3 !Coefficiente di Poisson acciaio <\/div>\n
!e AISI304<\/div>\n
rho=7850 !Densità acciaio<\/div>\n
E1=196e+9 !Modulo di young AISI304<\/div>\n
rho1=7910 !Densità AISI304<\/div>\n
 <\/div>\n
rho2=3500 !Densità ABS<\/div>\n
E2=70e+6 !Modulo di young ABS<\/div>\n
ni2=0.37 !Coefficiente di Poisson ABS<\/div>\n
 <\/div>\n
\/prep7<\/div>\n
!Spigoli telaio<\/div>\n
k,1 $ k,2,l $ k,3,l,,w $ k,4,,,w<\/div>\n
k,5,,h $ k,6,l,h $ k,7,l,h,w $ k,8,,h,w<\/div>\n
k,9,,h1 $ k,10,l,h1 $ k,11,,h,w1 $ k,12,l,h,w1<\/div>\n
k,13,,h,w2 $ k,14,l,h,w2 $ k,15,,h,w3<\/div>\n
k,16,l,h,w3 $ k,17,,h2<\/div>\n
 <\/div>\n
!Spigoli cassetta<\/div>\n
k,18,lc1,hc1,wc1 $ k,19,lc2,hc1,wc1<\/div>\n
k,20,lc2,hc1,wc2 $ k,21,lc1,hc1,wc2<\/div>\n
k,22,lc1,hc2,wc1 $ k,23,lc2,hc2,wc1<\/div>\n
k,24,lc2,hc2,wc2 $ k,25,lc1,hc2,wc2<\/div>\n
 <\/div>\n
!Spigoli staffe<\/div>\n
k,27,lc1,h,w1 $ k,28,lc1,hs1,w1 $ k,29,lc1,hs2,w1<\/div>\n
 <\/div>\n
k,31,lc1,h,w3 $ k,32,lc1,hs1,w3 $ k,33,lc1,hs2,w3<\/div>\n
 <\/div>\n
k,35,lc2,h,w1 $ k,36,lc2,hs1,w1 $ k,37,lc2,hs2,w1<\/div>\n
 <\/div>\n
k,39,lc2,h,w3 $ k,40,lc2,hs1,w3 $ k,41,lc2,hs2,w3<\/div>\n
 <\/div>\n
k,42,lcc1,hcc2,wc2 $ k,43,lcc1,hcc1,wc2<\/div>\n
 <\/div>\n
k,44,lcc2,hcc2,wc2 $ k,45,lcc2,hcc1,wc2<\/div>\n
 <\/div>\n
!KEYPOINT CERNIERE\/CHIUSURE<\/div>\n
k,56,lcera1,hcc2,wc2 $ k,57,lcera2,hcc2,wc2<\/div>\n
k,58,lcera2,hcer2,wc2 $ k,59,lcera1,hcer2,wc2<\/div>\n
 <\/div>\n
k,60,lcerb1,hcc2,wc2 $ k,61,lcerb2,hcc2,wc2<\/div>\n
k,62,lcerb2,hcer2,wc2 $ k,63,lcerb1,hcer2,wc2<\/div>\n
 <\/div>\n
k,64,lcerc1,hcer1,wc2 $ k,65,lcerc2,hcer1,wc2<\/div>\n
k,66,lcerc2,hcc1,wc2 $ k,67,lcerc1,hcc1,wc2<\/div>\n
 <\/div>\n
k,68,lcerd1,hcer1,wc2 $ k,69,lcerd2,hcer1,wc2<\/div>\n
k,70,lcerd2,hcc1,wc2 $ k,71,lcerd1,hcc1,wc2<\/div>\n
 <\/div>\n
k,72,lcere1,hcer1,wc2 $ k,73,lcere2,hcer1,wc2<\/div>\n
k,74,lcere2,hcc1,wc2 $ k,75,lcere1,hcc1,wc2<\/div>\n
 <\/div>\n
!KEYPOINT COPERCHIO<\/div>\n
k,76,lcop1,hcop2,wc2 $ k,77,lcop2,hcop2,wc2<\/div>\n
k,78,lcop2,hcop1,wc2 $ k,79,lcop1,hcop1,wc2<\/div>\n
!Rinforzo coperchio<\/div>\n
k,80,lcop1,hcop2,wc2-0.01 $ k,81,lcop2,hcop2,wc2-0.01<\/div>\n
k,82,lcop2,hcop1,wc2-0.01 $ k,83,lcop1,hcop1,wc2-0.01<\/div>\n
 <\/div>\n
!Ritti<\/div>\n
l,1,17 $ l,17,9 $ l,9,5 $ l,2,10 <\/div>\n
l,10,6 $ l,3,7 $ l,4,8<\/div>\n
 <\/div>\n
!Traversi e longheroni<\/div>\n
l,1,2 $ l,2,3 $ l,3,4 $ l,4,1<\/div>\n
l,5,6 $ l,6,12 $ l,12,14 $ l,14,16 $ l,16,7<\/div>\n
l,7,8 $ l,8,15 $ l,15,13 $ l,13,11 $ l,11,5<\/div>\n
l,11,27 $ l,27,35 $ l,35,12<\/div>\n
l,13,14 $ l,15,31 $ l,31,39 $ l,39,16<\/div>\n
 <\/div>\n
!Montante<\/div>\n
l,9,10<\/div>\n
 <\/div>\n
!Traverse oblique<\/div>\n
l,17,2 $ l,1,8 $ l,6,3<\/div>\n
 <\/div>\n
!Staffe<\/div>\n
l,27,28 $ l,28,29<\/div>\n
l,31,32 $ l,32,33<\/div>\n
l,35,36 $ l,36,37<\/div>\n
l,39,40 $ l,40,41<\/div>\n
 <\/div>\n
!Aree relative alla cassetta<\/div>\n
a,18,22,28,29 !A1<\/div>\n
a,22,25,32,28 !A2<\/div>\n
a,28,32,33,29  !A3<\/div>\n
a,21,33,32,25 !A4<\/div>\n
a,18,29,33,21  !A5<\/div>\n
a,18,22,23,19 !A6<\/div>\n
a,18,19,20,21  !A7<\/div>\n
a,22,23,24,25 !A8<\/div>\n
a,19,37,36,23  !A9<\/div>\n
a,23,36,40,24 !A10<\/div>\n
a,36,37,41,40  !A11<\/div>\n
a,20,24,40,41 !A12<\/div>\n
a,19,20,41,37 !A13<\/div>\n
 <\/div>\n
!Aree rinforzi cassetta<\/div>\n
a,25,42,43,21 !A14<\/div>\n
a,24,25,42,56,57,60,61,44 !A15<\/div>\n
a,24,44,45,20 !A16<\/div>\n
a,20,21,43,67,66,71,70,75,74,45 !A17<\/div>\n
 <\/div>\n
!Aree cerinere<\/div>\n
a,56,57,58,59 !A18 <\/div>\n
a,60,61,62,63 !A19<\/div>\n
a,64,65,66,67 !A20<\/div>\n
a,68,69,70,71 !A21<\/div>\n
a,72,73,74,75 !A22<\/div>\n
 <\/div>\n
!Area coperchio<\/div>\n
a,76,59,58,63,62,77,78,73,72,69,68,65,64,79 !A23<\/div>\n
!Aree rinforzo coperchio<\/div>\n
a,76,59,58,63,62,77,81,80 !A24<\/div>\n
a,77,81,82,78 !A25<\/div>\n
a,82,83,79,64,65,68,69,72,73,78 !A26<\/div>\n
a,76,79,83,80 !A27<\/div>\n
 <\/div>\n
!Tipologia elementi,materiali e sezioni<\/div>\n
et,1,beam188,,,3 !Beam 188 con f.f. cubica<\/div>\n
mp,ex,1,E !Modulo Young material 1<\/div>\n
mp,nuxy,1,ni !Coeff poisson material 1<\/div>\n
mp,dens,1,rho !Densità material 1<\/div>\n
sectype,1,beam,hrec,tubquad !Sezione tubolare quad<\/div>\n
secdata,wh1,wh1,th1,th1,th1,th1 !Dati sezione tubolare quad<\/div>\n
sectype,2,beam,chan,upn160 !Sezione upn160<\/div>\n
secdata,wu1,wu1,wu2,tu1,tu1,tu2 !Dati sezione upn 160<\/div>\n
sectype,3,beam,rect,staffa !Sezione staffe<\/div>\n
secdata,bb,bh !Dati sezione staffe<\/div>\n
et,2,shell63 !Shell163 cassetta<\/div>\n
mp,ex,2,E1 !Modulo Young material 2<\/div>\n
mp,nuxy,2,ni !Coeff Poisson material 2<\/div>\n
mp,dens,2,rho1 !Densità material 2<\/div>\n
r,1,tc !Spessore dello shell<\/div>\n
et,3,shell63 !Shell163<\/div>\n
r,2,ws !Spessore dello Shell delle staffe<\/div>\n
et,4,shell63 !Shell163 cerniere<\/div>\n
r,3,wcer !Spessore cerniere<\/div>\n
mp,ex,3,E2 !Modulo di Young material 3 ABS<\/div>\n
mp,nuxy,ni2 !Coeff di Poisson material 3 ABS<\/div>\n
mp,dens,3,rho2 !Densità ABS<\/div>\n
 <\/div>\n
!Meshing<\/div>\n
 <\/div>\n
!Mesh telaio<\/div>\n
esize,0.05<\/div>\n
lsel,r,line,,1,28<\/div>\n
latt,1,,1,,,,1<\/div>\n
lmesh,all<\/div>\n
lsel,all<\/div>\n
 <\/div>\n
lsel,r,line,,30,32<\/div>\n
latt,1,,1,,,,1<\/div>\n
lmesh,all<\/div>\n
lsel,all<\/div>\n
 <\/div>\n
lsel,r,line,,29<\/div>\n
k,1000,,-1e+12<\/div>\n
latt,1,,1,,1000,,2<\/div>\n
lmesh,all<\/div>\n
lsel,all<\/div>\n
 <\/div>\n
!Mesh staffe<\/div>\n
esize,0.02<\/div>\n
lsel,r,line,,33,40<\/div>\n
latt,1,,1,,,,3<\/div>\n
lmesh,all<\/div>\n
lsel,all<\/div>\n
 <\/div>\n
!Mesh cassetta<\/div>\n
asel,s,area,,1,17<\/div>\n
type,2<\/div>\n
mat,2<\/div>\n
allsel,all<\/div>\n
 <\/div>\n
asel,s,area,,23,27<\/div>\n
type,2<\/div>\n
mat,2<\/div>\n
allsel,all<\/div>\n
 <\/div>\n
!Mesh chiusure<\/div>\n
asel,s,area,,18,19<\/div>\n
type,4<\/div>\n
mat,3<\/div>\n
allsel,all<\/div>\n
 <\/div>\n
!Mesh cerniere in alluminio<\/div>\n
asel,s,area,,20,22<\/div>\n
type,4<\/div>\n
mat,2<\/div>\n
allsel,all<\/div>\n
amesh,all<\/div>\n
 <\/div>\n
\/eshape,1,1<\/div>\n
eplo<\/div>\n
 <\/div>\n
 <\/div>\n
!vincoli<\/div>\n
ksel,r,kp,,1,4,1<\/div>\n
nslk,r,n,all<\/div>\n
d,all,all<\/div>\n
allsel,all<\/div>\n
 <\/div>\n
!ANALISI MODALE<\/div>\n
 <\/div>\n
\/solu<\/div>\n
antype,modal<\/div>\n
modopt,lanb,all,10,500<\/div>\n
mxpand,,,,yes,,,<\/div>\n
save<\/div>\n
solve<\/div>\n
finish<\/div>\n
 <\/div>\n
!VIBRAZIONE LONGITUDINALE (LUNGO X)<\/div>\n
 <\/div>\n
!ANALISI SPETTRALE PSD<\/div>\n
 <\/div>\n
\/solu<\/div>\n
antype,spectrum,new<\/div>\n
spopt,psd,,yes<\/div>\n
sed,1.0,0.0,0.0<\/div>\n
!DEFINIZIONE SPETTRO DI RISPOSTA DELLA STRUTTURA<\/div>\n
psdunit,1,accg,9.81<\/div>\n
spfreq,1,10,40,500<\/div>\n
spval,1,,0.078,0.078,0.0078<\/div>\n
pfact,1,base<\/div>\n
!psdgraph<\/div>\n
psdres,acel<\/div>\n
save<\/div>\n
solve<\/div>\n
finish<\/div>\n
 <\/div>\n
 <\/div>\n
! COMBINAZIONE DEI MODI<\/div>\n
\/solu<\/div>\n
antype,spectr<\/div>\n
psdcom,0,244<\/div>\n
solve<\/div>\n
finish<\/div>\n
 <\/div>\n
!\/post26<\/div>\n
!store,psd,244<\/div>\n
!nsol,<\/div>\n
!rpsd<\/div>\n
!plvar<\/div>\n
 <\/div>\n
Can someone help me find the problem?<\/div>\n
Thank you!<\/div>\n
 <\/div>\n<\/div>\n","protected":false},"template":"","class_list":["post-239467","topic","type-topic","status-closed","hentry","topic-tag-mechanical","topic-tag-psd","topic-tag-responsespectrumanalysis-1"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["249415","23687"],"_bbp_author_ip":["23.56.168.190"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1193"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["239467"],"_bbp_forum_id":["27791"],"_bbp_engagement":["23687","249415"],"_bbp_voice_count":["2"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["239952"],"_bbp_last_active_id":["239952"],"_bbp_last_active_time":["2022-11-07 11:09:35"]},"test":"v-giordano3studenti-poliba-it"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/239467","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/239467\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=239467"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}