Procedure to extract Ritz vectors from dynamic testing data

Ritz vectors represent an alternative to mode shape vectors as suitable bas is vectors for n-dimensional space. In numerical analysis, Ritz vectors hav e been shown to offer superior performance in model reduction and time-simu lations. In this paper, we develop a methodology that is able to extract Ri tz vectors from single and multiple shaker dynamic tests. It is shown that the identified "experimental'' Ritz vectors are identical to the analytical ly derived Ritz vectors when the dynamic test shaker locations and directio ns are used as the reference force locations in the analytical derivation. The sensitivity of the extraction algorithm to measurement noise is shown t o be comparable to the sensitivity of modal parameters extracted from the s ame data set. Finally, to verify the feasibility and accuracy of the extrac tion algorithm, dynamic response data and static test results from the Spac e Shuttle vertical stabilizer assembly experimental database are utilized. Compared to static test data, accurate Ritz vectors were extracted using da ta from both accelerometer and laser-scanning vibrometer-based modal survey tests.