Is it possible to use submodelling after a PSD analysis?
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It is not exact because it does not include the cross-coupling between modes, but the attached input shows how submodelling might be done after a random vibration (PSD/ASD) analysis on a coarse mesh. /title,Demo of an approximate sumodelling technique to be used with PSD /prep7 et,1,42 mp,ex,1,1e7 mp,nuxy,1,.3 mp,dens,1,.3 rect,,20,,10 esize,2 amesh,1 nsel,s,loc,x,0 d,all,all nsel,all fini /solu antype,modal modop,lanb,5 mxpand,5,,,yes solve fini /solu antype,spectrum spopt,psd,,yes psdunit,1,accg psdfrq,1,1,8,10,12,18,20,22 psdval,1,.01,.05,.10,.10,.05,.01 ! approx 1 g^2 area under curve psdgraph,1 nsel,s,loc,x,0 d,1,uy,1 ! vertical excitation nsel,all pfact,1 psdcom solve fini /post1 set,3,1 plesol,s,x ! compare with submodel results fini save,coarse,db /clear /prep7 et,1,42 mp,ex,1,1e7 mp,nuxy,1,.3 mp,dens,1,.0003 rect,10,15,4,6 esize,1 amesh,1 nsel,s,ext nwrite nsel,all save,fine,db fini resu,coarse,db /post1 *do,iii,1,5 *get,mcoef,mode,iii,mcoef set,1,iii,sqrt(mcoef) cbdof,file,node,,file%iii%,cbdo *enddo fini resu,fine,db /solu *do,iii,1,5 /inpu,file%iii%,cbdo solve *enddo /post1 rsys,solu set,1,1 lcdef,1,2,1 lcoper,srss,1 lcdef,1,3,1 lcoper,srss,1 lcdef,1,4,1 lcoper,srss,1 lcdef,1,5,1 lcoper,srss,1 ! 1 sigma submodel results (compare with coarse 1 sigma results) plesol,s,x |
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