Analysis of Structural Response Data Using Discrete Modal Filters

Freudinger, Lawrence C. (1991) Analysis of Structural Response Data Using Discrete Modal Filters. Technical Report NASA CR-179448, Research Engineering, NASA Dryden Flight Research Center.

Full text available as: PDF - Requires Adobe Acrobat Reader or other PDF viewer.

Abstract

This thesis describes the application of reciprocal modal vectors to the analysis of structural response data. Reciprocal modal vectors are constructed using an existing experimental modal model and an existing frequency response matrix of a structure and can be assembled into a matrix that effectively transforms the data from the physical space to a modal space within a particular frequency range. In other words, the weighting matrix necessary for modal vector orthogonality (typically the mass matrix) is contained within the reciprocal modal matrix. The ability to extract the response of a particular mode from a system due to whatever forces may be acting on it has broad applicability, from operating data analysis and force identification to vibration control. The underlying goal of this work is mostly directed toward observing the modal state responses in the presence of unknown, possibly closed loop forcing functions, thus having an impact on both operating data analysis techniques and independent modal space control techniques. This study investigates the behavior of reciprocal modal vectors as modal filters with respect to certain calculation parameters and their performance with perturbed system frequency response data.

EPrint Type:	NASA Contractor Report
Keywords:	Aeroservoelastic, Flight test, Modal filter, Modal test, Reciprocal modal vector, Spatial filter, Vibration control
Subjects:	(01 - 09) Aeronautics: (05) Aircraft Design, Testing And Performance Aircraft/Project: Miscellaneous
ID Code:	312
Deposited On:	31 August 2004
Additional Information:	78 pages. This report was prepared as a thesis in partial fulfillment of the requirements of the University of Cincinnati for the degree of Master of Science.