Experimental modal vector extraction involves the determinationrnof complex eigenvectors. The degree of complexityrndepends on the amount and type of damping in the systemrnand how it manifests itself in the system matrices. When thernvectors are extracted, the scaling method must be known inrnorder to proceed with vector expansion, vector correlation,rnsystem optimization, model updating, etc. A companion paperrnon "System Matrix Optimization using a Complex AnalyticalrnModel Improvement (CAMI)" illustrates this point. Inrnorder to include damping in the equations of motion, the developmentrnof the four forms of state space equations is givenrnto define the modal system vector scaling. With this informationrnand the finite element system matrices, the vectors arernexpanded using various expansion techniques such asrnSEREP, IRS, GUYAN, etc. Once expanded, these vectorsrnare correlated using cross-vector correlation checks. CPOCrn(Complex Pseudo Orthogonality Correlation) is developedrnfor this correlation purpose. A simple model containingrnmass, damping and stiffness is generated to simulate thernexperimental complex test vectors. The system mass andrnstiffness matrices are used in the expansion and correlationrnprocedures.
展开▼
