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Real-Normalization of Experimental Complex Modal Vectors with Modal Vector Contamination

Hiremaglur, Rajeev
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1415283945

Abstract Details

2014, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
The main objective of this thesis is to investigate the effectiveness of various methods of real-normalization that have been used over the years. Special emphasis will be laid on the case of an axisymmetric structure, a circular plate, in which most of the identified modes of vibration occur as pairs of repeated or pseudo-repeated roots. Past research work done on such a structure at the Structural Dynamics Research Laboratory, University of Cincinnati, has shown that when modes are very close in frequency, with minimal spatial resolution, the non-dominant portion of the complex modal vector often correlates highly with one or more nearby modal vectors, which is frequently the modal vector of the pseudo-repeated root twin to the mode. This is referred to as modal vector contamination. Though complex modal vectors are usually obtained when a structure has non-proportional damping, there are several cases where complex modal vectors are obtained even when the structure is known to have proportional damping. One such case is the situation which leads to modal vector contamination. Though the problem tackled here is a result of the numerical solution procedure used in modal parameter estimation algorithms rather than due to physical causes, it is important to have a method that can yield an equivalent set of real-normal mode shapes for the purpose of correlation with the analytical model of the structure. The focus of this thesis will be to study and compare the different methods of real-normalization for such a case in which the complexity of the modal vector is due to contamination rather than the presence of non-proportional damping.
Randall Allemang, Ph.D. (Committee Chair)
David L. Brown, Ph.D. (Committee Member)
Allyn Phillips, Ph.D. (Committee Member)
95 p.
Mechanical Engineering
normalization of modal vectors; complex modal vectors of pseudorepeated roots; modal vector contamination of closely spaced modes; real normal modes and complex modes; rotation of complex modal vectors; SVD real-normalization of complex modal vectors

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Citations

  • Hiremaglur, R. (2014). Real-Normalization of Experimental Complex Modal Vectors with Modal Vector Contamination [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1415283945

    APA Style (7th edition)

  • Hiremaglur, Rajeev. Real-Normalization of Experimental Complex Modal Vectors with Modal Vector Contamination. 2014. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1415283945.

    MLA Style (8th edition)

  • Hiremaglur, Rajeev. "Real-Normalization of Experimental Complex Modal Vectors with Modal Vector Contamination." Master's thesis, University of Cincinnati, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1415283945

    Chicago Manual of Style (17th edition)

ucin1415283945
603
© 2014, some rights reserved.Creative Commons License Real-Normalization of Experimental Complex Modal Vectors with Modal Vector Contamination by Rajeev Hiremaglur is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.