[MBDyn-users] Eigenanalysis : compute deformed shape

Pierangelo Masarati masarati at aero.polimi.it
Thu Dec 3 12:53:03 CET 2009

Romuald NORET wrote:
> Hello,
> Thanks, I almost understood but I have a two last questions :
> Each line of VR (right eignevectors)  matrix are all degree of freedom of 
> the analysis :
> - It is a displacement or a position? I believe it is a position, but I 
> would like to be sure.

The values in the VR matrix related to node positions actually contain 
displacements, since they represent perturbations with respect to the 
reference configuration the eigenanalysis was computed about.

> - Each column is a degree of freedom, with real and imaginray part, for 
> instance : "(...) 0.0000000000000000e+00 0.0000000000000000e+00 
> 0.0000000000000000e+00  1.2489399063226966e-11-i*  1.1826429422174239e-03 
> (...)"
> In this example,
> "1.2489399063226966e-11-i*  1.1826429422174239e-03" means : Re(dof_i+1) 
> ="1.2489399063226966e-11" and Im(dof_i+1)="1.1826429422174239e-03"
> But how interpret this value :"0.0000000000000000e+00" means : Re(dof_i) 
> ="0" and Im(dof_i)="0" ?

Cheers, p.

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