Two techniques are commonly used for the determination of modal vector correlation. One technique, known as the Modal Assurance Criteria, has become extremely popular for the evaluation of analytical and experimental modal vectors. The second technique, based on the orthogonality relationship, uses both the analytical and experimental vectors along with the analytical mass matrix. Both of these techniques have limitations based of their formulations. A new Pseudo Orthogonality Check is presented to overcome some of the problems associated with the Modal Assurance Criteria and Cross Orthogonality Check that are routinely performed. This technique utilizes a System Equivalent Reduction/Expansion Process for the estimation of the mass matrix. The technique can be performed at either the reduced set of test degrees of freedom or at the full set of analytical degrees of freedom of the system. In addition, this technique can be biased to either the analytical or experimental modal data set. Several cases are presented to discuss and evaluate the new technique via comparisons using Modal Assurance Criteria and the standard Cross Orthogonality Check normally employed.
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