Enhanced methods of operational modal analysis
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Date
2018
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Publisher
University of New Brunswick
Abstract
In this thesis practical considerations for Operational Modal Analysis (OMA) are
discussed and two new methods of analysis are proposed. First, it is shown that although
natural frequencies may be accurately estimated, the estimated mode shapes when the
input excitation is other than Gaussian white noise contain significant errors, and in most
cases, accurate estimation is not feasible. A modal filter system is proposed which
implements a nonlinear optimization algorithm to perform OMA on a system subjected
to input excitations other than Gaussian white noise. The proposed method is validated
using numerical parametric studies on a 4 DOF analytical system subjected to a
generalized broadband excitation. Lastly, the application of automated OMA as a solution
for practical Structural Health Monitoring is discussed and a novel scale space based
frequency domain automated OMA method is proposed. The method is successfully
validated with a 4 DOF analytical system and a comparative study is performed using
vibration test data from a scale cable stayed bridge model.