Abstract
Many test articles exhibit slight nonlinearities which result in natural frequencies shifting between data from different references. This shifting can confound mode fitting algorithms because a single mode can appear as multiple modes when the data from multiple references are combined in a single data set. For this reason, modal test engineers at Sandia National Laboratories often fit data from each reference separately. However, this creates complexity when selecting a final set of modes, because a given mode may be fit from a number of reference data sets. The color-coded complex mode indicator function was developed as a tool that could be used to reduce a complex data set into a manageable figure that displays the number of modes in a given frequency range and also the reference that best excites the mode. The tool is wrapped in a graphical user interface that allows the test engineer to easily iterate on the selected set of modes, visualize the MAC matrix, quickly resynthesize data to check fits, and export the modes to a report-ready table. This tool has proven valuable, and has been used on very complex modal tests with hundreds of response channels and a handful of reference locations.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
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References
Hensley, D.P., Mayes, R.L.: Extending SMAC to multiple reference FRFs. In: Proceedings of the 24th International Modal Analysis Conference, St. Louis, Missouri, pp. 220–230 (Jan. 2006)
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© 2019 The Society for Experimental Mechanics, Inc.
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Mayes, R.L., Rohe, D.P. (2019). A Color-Coded Complex Mode Indicator Function for Selecting a Final Mode Set. In: Mains, M., Dilworth, B. (eds) Topics in Modal Analysis & Testing, Volume 9. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-74700-2_29
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DOI: https://doi.org/10.1007/978-3-319-74700-2_29
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