A method, based on the theory of a generalized inverse of the measured modal matrix, is used to improve the mass and stiffness matrices of a finite element model. The method, using the measured normal modes and frequencies, directly calculates a set of minimum changes in the physical matrices which constrains the resulting mass and stiffness matrices to produce an equivalent eigen-solution. The technique produces insight into the character of the measured modal information such that a sensitivity analysis procedure can be established. The procedure also can be used to identify discrepancies in the measured modes. A simplified analytical model and an experimental modal data base are developed to study the method of generalized inverse and the sensitivity analysis of the modified matrices. Parameters are produced to assess the quality of the experimental modal information and assist the structural analyst in experimental modal analysis and structural dynamics.
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